View source for Ruler

{{version|1.25}}
{{expand|with=<nowiki />
*information about ‘Introduce New Heir’ action - introduced with Emperor DLC.
*the modifier ‘Average monarch lifespan’ (monarch_lifespan).}}
Each country is headed by a '''ruler'''. In EU4, rulers are influential in the running of a country, having between 0 and 6 points of [[Monarch power|administrative, diplomatic and military skill]];  these skills contribute directly to the nation's monthly generation of monarch power. Rulers may be either a ''monarch'', who as an heir inherits the title from a relative in a [[monarchy]], or an elected leader of a [[republic]] or [[theocracy]], chosen by the AI or player at regular intervals.

== Monarch power ==
{{SVersion|1.25}}
When generated (by event or by random chance), rulers/heirs have their monarch power set.

The formula for this is simple: <math>random(0-3) + random(0-3)</math>.

For [[lucky]] nations, the formula is: <math>random(0-3) + random(0-3) + random(0-1)</math>. (This can equal 7, but will in that case get reduced to 6)

For generation of regencies, the formula is <math>random(0-3) + random(0-3) - 1</math>, with lucky nations not getting the "-1" modifier.

{| class="wikitable"
|-
! Point Probability !! Regular Nations/Lucky Regencies !! Regencies !! Lucky Nations
|-
| 0 || 1/16 (2/32) || 3/16 (6/32) || 1/32
|-
| 1 || 1/8 (4/32) || 3/16 (6/32) || 3/32 
|-
| 2 || 3/16 (6/32) || 1/4 (8/32) || 5/32 
|-
| 3 || 1/4 (8/32) || 3/16 (6/32) || 7/32 
|-
| 4 || 3/16 (6/32) || 1/8 (4/32) || 7/32 
|-
| 5 || 1/8 (4/32) || 1/16 (2/32) || 5/32 
|-
| 6 || 1/16 (2/32) || 0 || 1/8 (4/32)
|-
| Exp. Val. || 3.00 || 2.06 || 3.47
|-
| Std. Dev. || 1.58 || 1.48 || 1.60
|}

Several missions, ideas and events provide bonuses to monarch power:

{{Bonus table|monarch diplomatic skill}}
{{Bonus table|monarch military skill}}
{| class="wikitable"
|+
Permanent Boni :
!Skill Type
!Bonus
!Source
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|The Livonian Enlightened Monarchy government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|The Venetian government government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|The Sortition government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|The [[Republic#President For Life|President For Life]] government reform
|-
|[[file:Local_heir_administrative_skill.png|24x24px|alt=]][[file:Local_heir_diplomatic_skill.png|24x24px|alt=]][[file:Local_heir_military_skill.png|24x24px|alt=]]
|{{green|+1}}
|The [[Monarchy#Legislative Sejm|Legislative Sejm]] government reform for local heir
|-
|{{icon|monarch administrative skill|24px}}/ {{icon|monarch diplomatic skill|24px}}/ {{icon|monarch military skill|24px}}
|{{green|+1}}
|The Education of the Theocrat and Kingdom of God government reforms allow to choose one for every next ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|The [[Mamluks#Mamluk government|Mamluk government]] government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|The "Reorganized Ottoman government" government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|The Lithuanian Grand Empire government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|The Kingdom of God government reform; for future rulers.
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
|The [[Monarchy#Chakravarti|Chakravarti]] government reform
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
|The "Modernized Ottoman government" government reform
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
|The [[Monarchy#System of Councils|System of Councils]] government reform
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
|The Dynastic Administration government reform
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
| With the {{icon|moh|24px}} Mandate of Heaven DLC enabled; the Reshape Bureaucratic Ranks celestial reform; for future rulers.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|The [[Monarchy#Power_Structure|Imperial Austrian Monarchy]] government reform; for future rulers.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|The Livonian States General government reform; for future rulers.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Completing the [[Bohemian_missions#Peace_in_Europe|Bohemian mission]]: Peace in Europe, current and future rulers.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|The Right to Petition government reform
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|The Somalian Theocracy government reform
|-
|{{icon|monarch military skill|24px}}
|{{green|+3}}
|The [[Prussia#Prussian Monarchy|Prussian monarchy]] government reform; for future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|The Livonian Militarist Monarchy government reform; for future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|The Zulu Tribe government reform; for future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+1}}
| Completing the [[Albanian_missions#End_Turkish_Rule|Albanian mission]]: End Turkish Rule current and future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+1}}
|The Tengri "Legacy of the Steppes" government reform; for future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+1}}
|The Japanese "Supreme Shogunate" government reform; for future rulers.
|-
|{{icon|monarch military skill|24px}}
|{{green|+1}}
|The "The Sisterhood of Jean d'Arc" government reform; for future rulers.
|}
{| class="wikitable"
|+
Temporary Boni :
!Skill Type
!Bonus
!Source
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1/2/3}}
|Severity of reward depends on how the Finnish mission : Defend Independence, was completed; current Ruler
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|The [[Polynesian events#Menehune Blessing|Polynesian event]] Menehune Blessing
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|Completing the Danish mission: Eliminate Novgorod; current Ruler
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|Completing the Teutonic mission: An absolute State; current Ruler
|-
|{{icon|monarch administrative skill|24px}}{{icon|monarch diplomatic skill|24px}}{{icon|monarch military skill|24px}}
|{{green|+1}}
|Potential reward for completing the Lithuanian mission: March West; current Ruler
|-
|{{icon|monarch administrative skill|24px}}/ {{icon|monarch diplomatic skill|24px}}/ {{icon|monarch military skill|24px}}
|{{green|+1}}
|One at random for completing the Gotlander mission: Renowned Pirate King; current Ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|Potential reward for completing the Lithuanian mission: Develop Ruthenia; current Ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|Potential reward for completing the Finnish mission: Finetune our Finances; current Ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|Potential reward for completing the Finnish mission: Turku Academy; current Ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+2}}
|Potential reward for completing the Teutonic mission : Embrace Religious Ideas; current Ruler
|-
|{{icon|monarch administrative skill|24px}}
|{{green|+1}}
|Reward for completing the Lithuanian mission: Stabilize the interior; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+3}}
|Completing the Danish/ Swedish/ Norwegian mission: Multicultural Empire; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|Completing the [[Austrian missions#Shift the Balance|Austrian mission]]: Shift the Balance for current ruler, heir and future monarchs, duration {{icon|time}} 30 years.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|Completing the [[Savoyard missions#All Bases Covered|Savoyard mission]]: All Bases Covered duration {{icon|time}} 30 years.
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|Completing the Polish mission: Proclaim a new Empire; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+2}}
|Potential reward for completing the Polish mission: Balance the Princely Lands; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Completing the [[Savoyard missions#All Bases Covered|Savoyard mission]]: All Bases Covered; Ruler and heir
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Polish mission: Support the Merchants; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Lithuanian mission: Emblem of Faith; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Danish mission:The Religious league; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Swedish mission:The Religious league; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Livonian mission:Support the Holy league; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Teutonic mission:Join the League war; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Danish mission:Spread the Reformation; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Swedish mission: The Protestant Sword; current Ruler
|-
|{{icon|monarch diplomatic skill|24px}}
|{{green|+1}}
|Potential reward for completing the Finnish mission: Seize the Means; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Danish mission: The Nobles of Sweden; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Danish mission:The Religious league; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Swedish mission:The Religious league; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Livonian mission:Support the Holy league; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Teutonic mission:Join the League war; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Completing the Danish mission:Spread the Reformation; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Potential reward for completing the Polish mission: Throne of Bohemia; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+2}}
|Potential reward for completing the Teutonic mission : Embrace Religious Ideas; current Ruler
|-
|{{icon|monarch military skill|24px}}
|{{green|+1}}
|Completing the Swedish mission: The Protestant Sword; current Ruler
|}

===General/Admiral Rulers===

With certain government reforms, a General or Admiral will become Ruler on Monarch death. <br>
These Reforms are :
*{{icon|General}}General :
**[[A Dynastic Theocracy]]
**[[Military Dictatorship]]
**[[Stratocratic Administration]]
**[[Military Rulership]]
**[[Military Electorate]]
**[[Land of the Christian Sun]]
**[[Livonian Mercenary State]]
*{{icon|Admiral}}Admiral :
**[[Lords of the Sea]]
**[[Republic#Pirate_King|Pirate King]]
**[[Board of Admirals]]
**[[Livonian Admiralty]]
**[[Livonian Thalassocracy]]


The skill of the ruler depend on their Fire, Shock and Maneuver pips. In particular the formula is <math>\left\lfloor\frac{(random(0-3) + random(0-3))\cdot(9 + Fire + Shock + Maneuver)}{18}\right\rfloor</math> for every skill each. <br>
<small>''Note that if the total of "Fire + Shock + Maneuver" is higher than 18, it is set to 18 in the Formula.'' </small><br>
This means that a theoretical 0 pip general could be turned into everything from a 0/0/0 to a 3/3/3 ruler.

{| class="wikitable"
|-
!Sum Pips!!Exp. Val. !! Std. Dev.
|-
| 0||1.75||0.82
|-
|1||1.75||0.82
|-
|2||1.81||0.94
|-
|3||2.00||1.06
|-
|4||2.12||1.21
|-
|5||2.37||1.21
|-
|6||2.62|| 1.21
|-
|7||2.81 ||1.33
|-
|8||3.00 || 1.58
|-
|9||3.00|| 1.58
|-
|10||3.00 ||1.58
|-
|11||3.12 || 1.76
|-
|12||3.31|| 1.89
|-
|13||3.56 ||1.90
|-
| 14 ||3.75||1.78
|-
|15||3.75 || 1.78
|-
|16||3.93|| 1.95
|-
|17||3.93 ||1.95
|-
|18||4.31 || 1.82
|}

{| class="wikitable"
!Prob. of *at least* total ruler power:!!Leader Tot.: 0!!Leader Tot.: 1!!Leader Tot.: 2!!Leader Tot.: 3!!Leader Tot.: 4!!Leader Tot.: 5!!Leader Tot.: 6!!Leader Tot.: 7!!Leader Tot.: 8!!Leader Tot.: 9!! Leader Tot.: 10!!Leader Tot.: 11!!Leader Tot.: 12 !! Leader Tot.: 13!!Leader Tot.: 14!!Leader Tot.: 15!!Leader Tot.: 16 !! Leader Tot.: 17!!Leader Tot.: 18
|-
| 0||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.
|-
|1|| 0.993|| 0.993|| 0.993|| 0.993||0.993||0.993||0.993||0.993||0.993||1.||1.||1.||1.||1.||1.||1.||1.||1.||1.
|-
|2 ||0.947 ||0.947 ||0.947 ||0.974 ||0.974||0.974|| 0.974||0.974||0.974||0.998||0.998||0.998||0.998||0.998||0.998||0.998||0.998||0.998||0.998
|-
|3|| 0.807|| 0.807|| 0.82||0.908||0.908||0.927||0.927||0.927 ||0.927||0.993||0.993||0.993||0.993||0.993||0.993||0.993||0.993||0.993||0.995
|-
| 4||0.563||0.563||0.624||0.796||0.796||0.835||0.848||0.848||0.848||0.979|| 0.979||0.979||0.979||0.979||0.979||0.982||0.982||0.982||0.991
|-
| 5||0.297||0.297||0.404||0.609||0.609||0.701 || 0.734 || 0.734 || 0.734|| 0.95||0.95||0.95 ||0.95 ||0.95 ||0.952||0.964||0.964||0.964||0.979
|-
| 6||0.111||0.111||0.211||0.413||0.413|| 0.532 || 0.594 || 0.594 || 0.594 || 0.897 ||0.897 ||0.897 ||0.897 ||0.899 ||0.908 ||0.937 ||0.937 ||0.937 ||0.959
|-
|7||0.027||0.027||0.092||0.222||0.222||0.349||0.444||0.444||0.444||0.815||0.815||0.815||0.815||0.821||0.843||0.89||0.89 || 0.89||0.936
|-
|8|| 0.004||0.004||0.026||0.102||0.102||0.196||0.303||0.303||0.303||0.704||0.704 || 0.704||0.704||0.719||0.763||0.824||0.824||0.824||0.888
|-
|9||0.||0.||0.007||0.034||0.034||0.087||0.188||0.188||0.188||0.571||0.571||0.571||0.571||0.6||0.662||0.738||0.738|| 0.738 || 0.823
|-
|10||0.||0.||0.||0.01||0.01 || 0.025 || 0.103 || 0.103 || 0.103 || 0.429 || 0.429 || 0.429 || 0.429 || 0.475 || 0.547||0.651||0.651||0.651||0.767
|-
| 11 || 0. || 0. || 0. || 0.002 || 0.002 || 0.004 || 0.05||0.05||0.05|| 0.296|| 0.296|| 0.296|| 0.296||0.352||0.433||0.536||0.536||0.536||0.653
|-
| 12 || 0. || 0. || 0. || 0. || 0. ||0. || 0.021 || 0.021 || 0.021 || 0.185 || 0.185||0.185||0.185|| 0.246||0.319||0.422||0.422||0.422||0.547
|-
|13||0.||0.||0.||0.|| 0.||0.||0.007||0.007||0.007||0.103||0.103||0.103||0.103||0.158|| 0.231||0.301||0.301 ||0.301||0.466
|-
|14||0.||0.||0. ||0. || 0.||0. ||0.002||0.002||0.002||0.05|| 0.05|| 0.05||0.05||0.092||0.152||0.213 ||0.213||0.213||0.308
|-
|15||0.||0.||0.||0. ||0.||0.||0.||0.|| 0.||0.021||0.021|| 0.021||0.021||0.053||0.079 ||0.132||0.132||0.132||0.237
|-
|16|| 0.||0.||0.||0.||0.||0.||0.|| 0.|| 0.||0.007||0.007||0.007 ||0.007||0.026 ||0.046|| 0.073||0.073||0.073||0.158
|-
|17||0.||0.||0.||0. || 0.||0. ||0.|| 0.||0.||0.002 ||0.002||0.002||0.002 ||0.007||0.026||0.026||0.026||0.026||0.053
|-
|18||0.||0.||0.||0.||0.||0.||0.||0.||0. ||0.||0.||0.||0. ||0.007||0.007||0.007||0.007 ||0.007||0.053
|}

== Personalities==
{{SVersion|1.30}}
[[File:Ruler_Personality.png|right|thumb|330px|A ruler developed a trait.]]
{{main|Personalities}}
Rulers of AI nations will have personalities that determine how they act. The particular personality assigned to each ruler is strongly correlated with the category of their highest skill, with administrative, diplomatic, and military skill leading to administrator, diplomat, and militaristic personalities respectively. Knowledge of this can help players predict the personality of an upcoming heir.

With the {{icon|rom}} [[Rights of Man]] expansion, every single ruler/heir have traits that develop over time. These personalities grant a modifier for the nation as well as changes to the AI's actions. All personalities unlock new options in some events, as well as have events of their own.

==Monarchy==
{{SVersion|1.25}}
Monarchs (rulers of countries with a [[monarchy]] government type) rule until death, and have an heir to succeed them and inherit the throne. The system is nearly identical to EU3's system of monarchs, heirs and dynasties.

===Dynasty===
A dynasty is acquired through:

*Spread from other dynasties
*Pretender rebels
*Events 
**Dynamic “disasters”, such as the [[War of the Roses]] or the [[Castilian Civil War]], or generic events, such as some of the [[Dynastic events]] and particularly those that may happen when a country is heirless

Most countries at game start, in 1444 or in other bookmarks, already have a dynasty. There are some exceptions to this, notably Poland in 1444 which is in the special situation of [[interregnum]].

==== Share and spread====

Dynasties, especially those initially found in powerful countries, can be shared by several countries. A shared dynasty grants a +25 bilateral bonus to [[relations]] with all countries with which the dynasty is shared. 

Spreading your dynasty involves first and foremost [[royal marriages]], [[prestige]] and several other parameters, which, as of now, can only be guessed through in-game empirical evidence.

====Succession and Inheritance====

A shared dynasty is one of the requirements for the [[claim throne]] mechanic, which is an important part of the [[succession war]] and [[inheritance]] mechanics.<ref>For the most complete guide regarding these mechanics, please refer to the following [https://forum.paradoxplaza.com/forum/index.php?threads/guide-to-royal-marriages-personal-unions-and-claim-throne.788829/ forum post on the official EU4 forums], summarized on this wiki on the [[personal union]] page.</ref>

===Royal marriage===
{{hatnote|For the diplomatic effects of royal marriage between countries, see [[Diplomacy#Royal marriage]]}}
{{hatnote|For the mechanics of personal unions formation, see [[Personal union]]}}
[[File:Queen.jpg|right|thumb|330px|Entering a royal marriage with another nation.]]
Countries ruled by monarchs may arrange royal marriages with others.

A royal marriage is one of the requirements for the [[claim throne]] mechanic, while being an important part of the [[succession war]] and [[inheritance]] mechanics.

Each royal marriage gives 0.1 [[legitimacy]] per year, but entering into a marriage with a nation with lower prestige causes an immediate drop of 1-5 legitimacy.

====Consort====
{{Expansion|rom}}
A royal marriage has a chance to produce a consort to the nation's ruler (queen-consort for male rulers or prince-consort for female rulers). The consort will belong to the other nation's dynasty. There is also a chance of getting a consort of a local minor noble dynasty if the nation gains an heir without a consort present. Having a consort will give a slight relations boost with the nation of origin.

The consort will take the role of the de facto ruler in a time of regency - thus lifting the restrictions placed by the regency rule - until the designated heir comes of age. It is possible for the consort to remain in power after the heir becomes old enough through events or in case of death.

=== Heir===
{{SVersion|1.25}}
A monarch has an heir, who may represent a son, daughter, cousin or other relative. In a [[monarchy]], an heir has an associated claim strength (from weak to strong), which determines their starting [[legitimacy]] upon succeeding the throne. Heirs come of ruling age at 15, a [[regency]] will otherwise rule until they come of age. 

In cases where no heir exists, the mention "No Legal Heir" will stand instead of the heir's name, age and claim strength. If at ruler's death, there is still no heir, the country may:

*Be at the receiving end of a dynasty spread from another country it has a royal marriage with
*Become the junior partner of a [[personal union]]
*Face a [[succession war]] at the issue of which it becomes the junior partner of a personal union with the winning country.
* Get a new ruler from the deceased monarch's dynasty
*Get a new ruler from a randomly-chosen dynasty among the ones figuring in the game files for the country ("A XYZ noble will accede to the throne")
* Be inherited directly (See [[inheritance]])

The determination of which scenario is to happen rests on several factors, such as, among others, royal marriages, dynasty, rivals, prestige, legitimacy, military strength and total [[development]].

====Name====
{{Expansion|eld|cos}}
The player can choose the name of a new heir or re-roll another random name.

==== Heir chance ====
If a monarchy has no heir, the daily chance of a new heir appearing is <math>\frac{m \cdot a \cdot (1 + b)}{182500}</math> where

*<math>m</math> is BASE_HEIR_BIRTH which is 120 if unmodded.

*<math>a</math> is 0.5 if the current monarch ruled for more than 30 years, 1 otherwise. This modifier changes from 1 to 0.5 on 1 January in the 30th year of reign. Do note that some starting monarchs ruled before age of 15. Example: starting ruler of {{flag|Toki}}, birthdate is 1 January 1406, inaugurated in 23 April 1414, modifier is 0.5 at the earliest game start in 1444.

*<math>b</math> is sum of all {{icon|heir chance|30px}}heir chance modifiers.

In practical terms, here are some examples and the resulting probability:

{| class="wikitable"
!Situation!!<math>a \cdot (1 + b)</math>!!Chance of at least one heir in one year
|-
|Infertile & more than 30 years||0.375||8.61%
|-
|More than 30 years||0.5||11.31%
|-
|Infertile||0.75||16.48%
|-
|Normal||1||21.34%
|-
|Trading in dyes||1.33|| 27.33%
|-
|Fertile||1.5||30.24%
|-
|Sunni, Shia, or Ibadi||2 ||38.14%
|-
|Fertile & Sunni & Trading in Dyes ||2.83 ||49.33%
|}

'''Ideas and policies:'''
{{bonus table|heir chance}}
'''Further modifiers:'''
{|
| align="right" |{{green|+100%}}||with {{religion|Muslim}} as state religion.
|-
| align="right" |{{green|+50%}}|| with a ruler which has the {{icon|fertile|24px}} ‘Fertile’ personality.
|-
| align="right" |{{green|+33%}}||for trading in {{icon|dyes}} dyes.
|-
| align="right" |{{green|+5%}}||for each {{icon|royal marriage}} royal marriage.
|-
| align="right" |{{green|+25%}}||as [[lucky]] nation (only AI controlled countries).
|}

Some events may also add positive or negative {{icon|heir chance|30px}}heir chance modifiers.

If a monarch dies and an heir is old enough to rule (age 15), there is a separate unknown chance of getting a new heir instantly.

====Heir claim ====
Heir claim represents the legitimacy of the heir to the throne in the eyes of the people, and is a number ranging from 0–100 that is assigned when an heir is generated. Upon ascending to the throne, a ruler's legitimacy will be set to the value of their heir claim. In game, heir claim will be shown only as '''Strong''', '''Average''', or '''Weak''', which gives a rough idea of the value. Having a lower heir claim (Average or Weak) gives a higher chance of pretender rebels arising.

The formula for heir chance appears to be random, but weighted to give higher values, making the majority of heirs have a Strong claim.

If the {{icon|lev}} Leviathan DLC is active, Heirs will usually start with an Average claim, however their claim changes every month. Usually it increases, but some modifiers can make it decrease.

Monthly change is calculated as follows :

* Base Value : {{Green|+0.20}} (says +0.21, but is actually less)
* Prestige : {{Red|-0.05}} to {{Green|+0.05}} at -100/ +100 Prestige
* Corruption : {{Green|+0.03}} at 100 Corruption

Other ways to change the claim strength are taking the "Support Ruling Dynasty" [[Parliament#Issues|parliamentary debate]], which increases the heir claim by {{green|+10}} and two events for {{flag|Ming}}, and [[Art_of_War_events#The_Fires_of_Hell|one]] from the {{icon|aow}} Art of War DLC.

====Introduce new heir====
{{expansion|emp}}
If a monarchy has no heir, it can choose to introduce a new heir at a cost of {{icon|legitimacy}} {{red|−20}} [[Legitimacy]] and {{icon|Prestige}} {{red|−20}} [[Prestige]], so long as the country meets the following requirements:

*Not in a regency
*Not at war
*Positive prestige
*At least 90 legitimacy

An heir introduced in this way will come from a local dynasty that is different from the country's current ruling monarch and will have a weak claim to the throne.

Further, introducing a new heir will grant a 20-year [[Casus_belli#Restoration_of_Union|Restoration of Union]] casus belli to any country with whom the monarchy has a royal marriage. Allies with a Restoration of Union casus belli may become {{icon|domineering attitude}} [[Relations#Attitude|Domineering]] and will tend to break any alliance with the monarchy.

====Disinherit====
{{Expansion|rom}}
A country may disinherit an heir if so is wished, at a cost of {{icon|Prestige}} {{red|−50}} prestige. After this action is done the country won't have any legal heir, and will be at risk of falling under a [[Personal Union]], just like any other country without a legal heir (It is not possible to "return" to the disinherited heir).

====Regency====
A country whose ruler is a child (usually because he or she was still a child when the previous ruler died) will be ruled by a ''regency council'', using its skills instead of the ruler's, until the ruler comes of age at 15 years.<ref>See in {{path|defines}}: AGE_OF_ADULTHOOD = 15,</ref> The Regency will be provided by the Estate with the highest influence in your country, if {{icon|lev}} Leviathan is active. While in regency, a country cannot declare war unless following the [[Nahuatl]] religion (but can still be called to war or be attacked). Additionally, while in regency, the country gets the following modifier:{{#lsth:Static modifiers|Regency council}}

If a consort is present, they will take the reigns over the nation until the designated heir comes of age, effectively lifting the restrictions of placed by the regency rule (requires {{icon|rom}} Rights of Man DLC).

If the {{icon|lev}} Leviathan DLC is active, it is possible to extend the Regency for your Heir by 5 years, at the cost of {{Icon|legitimacy}} {{Red|-10}} Legitimacy. This might be desireable to further grow his claim before he takes power.

====Interregnum====
An interregnum is effectively anarchy; no leadership is in control of the country. This can happen when no heirs are available to a kingdom and its leader dies. It is rare even when a country has no dynasty or royal marriages, as a noble usually takes the throne, but it can occur. Interregnums generally do not last very long; a year is probably average, though they can last much longer. When the interregnum ends, a new leader will be chosen based on the same parameters as if the leader had just died, e.g. a dynasty from a royal marriage, or a new dynasty from the nobility of the country.

Nearby kingdoms in interregnum can be easy to take advantage of. If the player arranges a royal marriage, the new king will likely be a part of the player's dynasty. They will also have no heir. An heirless dynasty with a royal marriage can be [[Claim throne|Claimed]], giving a CB to form a Personal Union. Declaring war against a country one is married into causes stability loss, but this is a small price to pay.
It is possible for this tactic to fail, as other nations could form royal marriages as well. A high prestige will ensure that one's dynasty prevails.

In 1444, {{flag|Poland}} and {{flag|Hungary}} start this way due to their joint monarch having died without issue in the Battle of Varna, and {{flag|Bohemia}} also, because its lords did not recognize its previous ruler's posthumous son (Ladislaus the Posthumous) as legitimate. Hungary is scripted to get a specific dynasty (as Ladislaus gets accepted there, and he is a Habsburg), and Poland similarly gets a choice between a PU with {{flag|Lithuania}} or a local noble's dynasty. Bohemia does have possible events but there is still the possibility to get the player's dynasty. As such, nearby countries strong enough to take on Bohemia, such as {{flag|Austria}}, can get a big boost for the early years if they choose to do so.

===Abdication===
{{Expansion|rom}}
It is possible for a ruler to abdicate the throne and allow the next in line to take over the throne and be the new ruler. Note that this will ''not'' avoid the stability hit that would occur if the ruler died and succession occurred normally.
*To be able to abdicate, the following requirements must be met:
**Have an heir that's at least {{green|15}} years old
** Be at peace
**Have at least 50 legitimacy
**The current ruler must either:
*** be at least {{green|60}} years old
***have ruled for {{green|20}} years
*Costs
**{{icon|Legitimacy}} {{red|−20}} Legitimacy or {{icon|horde unity}} {{red|−20}} Horde unity
**{{icon|Prestige}} {{red|−50}} Prestige

===Deaths===
When a monarch dies, the country takes a {{red|−1}} stability hit. When a monarch leads an army in a battle or a siege, this results in a {{red|−2}} stability hit instead. Heirs that die either in battle or while sieging will result in a {{red|-1}} stability hit, while dying while not leading any units will not result in any stability hit, although there are certain events that may fire when an heir dies that can cause a stability hit.

==Republic==
{{SVersion|1.25}}
In most [[republics]], a group of people hold power over a country until the next election cycle, the length of which depending on the type of republic that is in control. In cases where there are no elections, rulers appear almost identically to those of a monarchy, though they lack a persistent dynasty. Republics do not have heirs, and have the associated [[republican tradition]] mechanic, rather than [[legitimacy]]. Republics are unable to obtain [[royal marriage|royal marriages]], unless they are either a Noble Republic, Italian Signoria, or a Dutch Republic.

===Election===
Elections take place at different times for different types of republics. For Merchant, Oligarchic, Constitutional, and Revolutionary republics, as well as the unique Dutch Republic and Ambrosian Republic, the time between elections is 4 years. For Administrative republics the time is 5 years between elections, and Noble republics have 8 years between elections.

Elections will offer a panel of three rulers, each inclined towards one particular skill: Administrative, diplomatic, or military. The ruler will have a 4 skill in that particular one, and 1 in both the others. 
Re-elections can be done at the price of {{icon|republican tradition}} republican tradition to upgrade the ruler's skills and keep him for another term; he will thus gain 1 in every skill (6 being the maximum), along with a chance to gain 50 power in one category.
The republican tradition cost for re-election is tied to the length of the election cycle: 2.5 republican tradition per year of ruling (e.g. a 4-year election cycle costs 10 republican tradition, an 8-year election cycle costs 20).

===Death===
An election may be held at any time for these republics if the head of the republic dies, and a republican leader does not cause a stability loss on their death, except for deaths in combat or while leading a siege which causes a {{icon|stability}} {{red|−1}} stability hit.

== Theocracy==
{{SVersion|1.25}}
Theocracies are states ruled by a religious head, and are subject to the [[devotion]] mechanic in place of [[legitimacy]]. Theocracies are unable to obtain [[royal marriage|royal marriages]] with other nations, reducing their diplomatic abilities somewhat.

===Heir===
Heirs of theocracies are chosen through an event, allowing players to choose from various bonuses and potential maluses. Theocratic heirs tend to be older, typically above 40 years, which means they usually do not rule for as long as monarchistic heirs. In this way, theocracies never have regency councils or interregnums, as they always have an heir, and their heirs are always old enough to lead. The [[monarch power]] stats of theocratic heirs are generated in the same way as regular monarchs, with a 3,3,3 heir being average and most likely to occur.

Unlike in monarchy, heir of theocracy can't be disinherited.

===Death===
Theocratic leaders do not cause stability loss on their death, except for deaths in combat or while leading a siege which causes a {{icon|stability}} {{red|−1}} stability hit.

==Chance of death and life expectancy==
{{SVersion|1.25}}
Every day, a monarch or heir has a daily chance of death <math>\frac{m \cdot a}{182500}</math> where <math>m</math> is MONARCH_DEATH (4 if unmodded) for monarchs and HEIR_DEATH (1 if unmodded) for heirs and <math>a</math> depends on the age bracket according to the following tables.

Note that the tables assume that the ruler is not a general, that heirs do not become monarchs (which shortens their life expectancy) and ignore special events that may kill a monarch or heir. a is different in the 31-40 age bracket between monarchs and heirs (possibly an oversight).

{| class="wikitable"
|-
!Monarch age !! a!!Chance of death within a year!! Chance of death within 10 years!! Average life expectancy at start of age bracket
|-
!0-10
| 1||0.80%|| 7.7% ||50.4
|-
!11-20
|1||0.80%||7.7%||54.6
|-
!21-30
|1 ||0.80%||7.7% ||57.8
|-
! 31-40
|1||0.80%||7.7%||60.4
|-
!41-50
| 2||1.6%||14.8%||62.5
|-
!51-60
|4 ||3.2%||27.4%||65.4
|-
! 61-70
| 10|| 7.7%||55.1%||69.0
|-
!71-80
|50||33.0%||98.2%||73.5
|-
!81-90
|300||91%||~100%||81.4
|-
! 91-
|1000 || 99.97%||~100% || 91.1
|}

{| class="wikitable"
|-
!Heir age!!a!!Chance of death within a year!!Chance of death within 10 years !!Average life expectancy at start of age bracket
|-
!0-10
|1||0.20% ||2.0%||68.2
|-
!11-20
|1||0.20%||2.0% || 69.7
|-
!21-30
|1||0.20% ||2.0%||70.6
|-
!31-40
|2|| 0.40%||3.9%||71.7
|-
!41-50
|2||0.40%||3.9%||73.1
|-
!51-60
|4||0.80%||7.7%||74.2
|-
!61-70
|10 ||2.0%||18.1%|| 75.7
|-
! 71-80
|50||9.5%||63.2%||77.9
|-
!81-90
|300||45.2%||99.8%||82.7
|-
!91-
|1000||86.5%||~100%||91.5
|}

Monarchs and heirs who have been made into a [[military leader]] for 5 or more years previous to the current date are also subject to the military leader death check as described for [[military leader|military leaders]], resulting in increased chance to die, which is further increased if assigned to an army, and again increased if in a battle or siege.

Note that the life expectancy in general depends on both the age and the time passed since the monarch was turned into a military leader; these tables list values valid just after the button to turn a monarch or heir into a military leader is pressed.

{| class="wikitable"
|-
!Monarch age!!Average life expectancy when turned into a general at that age and assigned to an army
|-
!0
|18.5
|-
!11
|29.5
|-
!21
|39.1
|-
!31
|48.4
|-
!41
|56.5
|-
!51
|63.0
|-
!61
|68.5
|-
!71
|73.4
|-
!81
|81.4
|-
!91
|91.1
|}

{| class="wikitable"
|-
!Heir age!!Average life expectancy when turned into a general at that age and assigned to an army
|-
!0
|19.9
|-
!11
|30.9
|-
!21
|40.7
|-
!31
|50.4
|-
!41
|59.8
|-
!51
|67.8
|-
!61
|73.5
|-
!71
|77.6
|-
!81
|82.7
|-
!91
|91.5
|}

Daily chance of death has no effect on:
*a ruler who was inaugurated less than 1 year ago
*an heir who is younger than 20 years

==See also==
*[[List of rulers]] (Warning: large)
*[[forum:636815|Dev diary 5]] focused on the changes to Rulers in EU4.

==Footnotes==
<references />

{{mechanics navbox|Internal country management}}
[[Category:Realm]]