This article is for the PC version of Stellaris only.
Population, also known as population units or pops, is the center of productivity and political action within an empire. They provide resources by working on districts and buildings, and influence if they are part of a specific faction.
Each planet has four variables that determine its demographic direction. A planet can have only one growing pop, one declining pop and one assembling pop at any time.
Pop growth represents the increase in population from natural reproduction and immigration. A new pop appears after () growth points have been accumulated. The base growth rate ranges from 0.03 to 6, with the default growth rate at 3. This is affected by the Carrying Capacity of the planet and the number of pops on the planet. There are no penalties applied if the population is below 50% of the Carrying Capacity. The base growth rate is modified by many factors, these apply to the total base growth rate after accounting for Carrying Capacty. Any species existing on the planet or which has immigration access to the planet may be selected to grow there. When choosing a species to grow, planets will generally prioritize species that are under-represented on the planet and have citizenship equal to that of the already existing species. Habitability is a major factor in Pop growth. Pops with very low habitability for a planet will only slowly reproduce or migrate to it or may not at all. Species can be chosen manually for growth if the Population Controls policy is set to Allowed. Pop growth stops when a planet has 5 Pops without Housing.
Pop decline represents the decrease of certain species on the planet due to purging or severe overcrowding. A pop will disappear after 100 decline points have been accumulated. By default, decline rate is −5 decline points per month. Overcrowded planets that have over-represented species will have those species begin to decline in numbers and be replaced by newly growing, under-represented species that have equal citizenship. Purging a particular species will cause that species to decline more rapidly depending on the purge species right.
Pop assembly represents a planet's capacity for constructing Mechanical, Machine, or Biological pops. Pop assembly can assemble either robotic or biological at a given time, both can not be produced simultaneously. Roboticist Jobs add +2 Monthly Robot Pop Assembly Points and Replicator Jobs add +1 Monthly Robot Pop Assembly Points. Spawning Drone Jobs add +2 Monthly Biological Pop Assembly Points and Clone Vats add +3 Monthly Biological Pop Assembly Points. Once () Assembly Points are reached a new robot pop is created on the planet. Non-sentient robotic pops do not migrate but can create overcrowding and unemployment. The constructed template is the one with the highest number of used trait points but can always be changed manually.
Migration is calculated by subtracting emigration push from immigration pull, both of which are determined by factors such as Housing, Stability and Unemployment. A planet with more emigration than immigration will have their growth lowered and the amount lowered will be added to potential immigration targets. Planets with higher immigration pull will receive a greater share of this migration, which is converted directly into pop growth. Signing migration treaties will allow migration to and from other empires and accepting refugees will also create immigration from planets outside the empire borders. A newly colonized planet gains +100 immigration pull and divides a total of +50 emigration push between all developed planets, until the Reassembled Ship Shelter is upgraded.
The exact mechanics by which a new pop is selected for growing/assembly is not fully known. However a bunch of values could be extracted from the defines file.
|Overcrowding_Decline_Threshold||1.25||At this amount of overcrowding (required housing / actual housing), pops start declining|
|New_Pop_Species_Randomness||0.5||The higher this is, the more random species selection of new pops will be|
|New_Pop_Same_Species_Weight||1.0||The higher this is, the more new pops will be weighted by number of same or subspecies pops|
|New_Pop_Exact_Species_Weight||0.5||The higher this is, the more new pops will be weighted by number of exact same species pops|
|New_Pop_Slavery_Weight||0.25||The higher this is, the more new pops will tend to be balanced between enslaved and non-enslaved species|
|New_Pop_Species_Div||0.05||The higher this is, the more planets will tend to grow species that are underrepresented on the planet|
|New_Pop_Habitability_Threshold||0.75||If habitability is under this, apply exponentially increasing penalties to new pop weight|
|New_Pop_Homeworld_Mult||2||Pops have increased weight for growing on their homeworld|
|New_Pop_Growth_Mod_Mult||0.33||How much does species growth mod trait matter for new pop weight|
|NEW_POP_Immigration_Mod_Mult||1||How much does species immigration growth mod trait matter for new pop weight (when there is immigration)|
|Pop_Decline_Threshold||3.0||A species will decline when there is another species with a growth priority this many times higher|
If the empire's policies allow it, resettlement will instantly move a pop from one planet to another. This costs an amount of energy, modified by the pop's stratum. Resettlement cost can be reduced by the following:
|Evacuation protocols edict||−50%|
|Operational Proxies tradition||−33%|
|Corvee System civic||−25%|
Each pop in an empire has a base happiness rating. It ranges from 0% to 100% and has a base level of 50%, and together with the Stratum's political power determines the approval rating, in addition to the following effects:
- Each point of Happiness above 50 adds +1% governing ethics attraction to free pops and +2% Authoritarian ethics attraction to slaves.
- Each point of happiness below 50 adds −1% governing ethics attraction to free pops and +10% Egalitarian ethics attraction to slaves.
- Each point of happiness above 50 gives each pop −0.02 crime, up to 0 per pop at 100% happiness.
- Each point of Happiness below 50 gives each pop +0.02 crime, up to +2 per pop at 0% happiness.
Fortunately, there are also many ways to improve happiness in an empire. Planetary edicts, civics, living standards, permanent modifiers, planet modifiers and ruler traits can positively affect happiness. Events may have an impact on planetary or empire happiness for a limited time as well.
Approval rating ranges from 0% to 100% and has a base level of 50%.
- Each point of approval rating above 50% adds +0.6 stability, up to +30 at 100% approval rating.
- Each point of approval rating below 50% adds −1 stability, up to −50 at 0% approval rating.
Most organic pops consume 1 food per month. Lithoid pops consume 1 minerals per month. Robots instead consume 1 energy per month. In addition, organic pops that are not part of a Gestalt Consciousness empire require a certain amount of consumer goods based on their living standards. Synthetics that are given citizen rights require it as well.
Housing represents the living space available for pops to live comfortably. Housing is primarily provided by districts, with city districts giving more housing than their resource-focused alternatives. Each pop requires 1 unit of housing by default but the housing demands of individual pops can change due to a variety of factors. If the number of pops exceeds the amount of housing it will cause stability to drop by and a flat +50 planet emigration push.
As a rule of thumb, each resource district exactly pays for itself in terms of housing, while the pops that work building jobs need city districts (or housing buildings) for their housing, though the capital building provides some buffer before cities are needed. This applies equally to ecumenopolises. The Agrarian Idyll civic gives extra housing to resource districts, allowing the empire to house its pops working building jobs mostly via resource districts.
Amenities represent the infrastructure and jobs dedicated to fulfilling the needs of the population. Individualist empires obtain amenities from a variety of jobs while Gestalt Consciousness empires obtain them primarily from Maintenance Drone jobs. High amenities cause increased happiness to free pops in regular empires and increased stability in Gestalt Consciousness empires, while insufficient amenities will lower them.
Amenities can be affected on an empire-wide basis by the following:
|One Vision ascension perk||-10%|
|Vultaum Reality Perforator relic||-10%|
|Ecological Protection resolution 2||-5%|
|Discourage Planetary Growth decision||+25%|
Strata represent pops' social classes. The higher a pop's stratum, the more political power they have and the more Consumer Goods they require for upkeep, according to their living standard. It also determines the resettlement cost.
If a pop takes a job above its stratum it will be promoted to the higher stratum. If there are no available jobs of equal or higher Stratum the pop will become unemployed, slowly demoting in stratum and causing happiness penalties at most levels of living standards.
Entire species can be enslaved by giving them a certain citizenship, which opens a new tab in the Species Rights menu called Slavery Type that determines what are the effects of slavery.
Enslaved pops also use only 0.75 amenities and 0.75 housing instead of 1, and can be further reduced if the slavery type is Servitude or Livestock. They also get −50% resettlement cost. Enslaved pops cannot join factions and have only 25% political power, or 18.7% if a Slave Processing Facility is present on the planet. However they can still increase crime if they're too unhappy.
Slave output can be affected by the following:
Slaves, Workers and Specialists
In addition to the Slave resource output modifiers, Worker resource output modifiers can also affect Slaves in worker jobs. As of 3.0.1 Slaves in Specialists jobs are affected by specialist output modifiers but not by Slave resource output modifiers, if in Indentured Servitude.
- Slaves working on Miner jobs can benefit from Worker resource output modifiers, such as Authoritarian and Strong.
If a modifier affects the resource output of both Workers and Slaves, it actually affect Slaves in Worker jobs twice.
- The Extended Shifts edict increases Slaves resource output by +10% and Workers resource output by +10%, resulting in an actual +20% bonus to Slaves in worker jobs.
Modifiers that affect Workers aside from the resource output ones don't affect Slaves.
- The Extended Shifts edict decreases Slaves happiness by −10% and Worker happiness by −10%. It does NOT cause the Slaves to suffer −20% happiness.
Ethics attraction modifiers
Ethics divergence is where a pop or group of pops decide to follow a different ethic than the general population. A materialist pop may decide to follow a more spiritual path and a pacifist culture might decide that peace is the path of the weak.
Each pop in an empire will only embrace a single, non-fanatic ethic. At the start of the game, the population will be made of the empire's governing ethics. As population expands and eventually is divided over various planets and sectors, certain segments may decide to adopt values that are different from the core values of the species due to various circumstances in and around the empire.
Each ethic has a certain attraction value attached for all pops, depending on both the empire's situation and their own. Each pop can only switch ethics once per year. The exact values and options that influence the attraction levels of certain ethics can be found at Ethics attraction. The attraction factors of ethics can be amplified by certain circumstances such as policies or traits.
Having a positive ethics attraction effect will let all actions that increase attraction to the government ethics result in even more attraction, and negative amounts will be decreased. With a modifier of 50%, an action that would increase attraction by 2 would instead increase by 3.
Hovering over a pop's ethic will display the attraction towards all ethics.
Robots are artificial pops and can be constructed once the required technology becomes available. They have the Mechanical trait, giving them +200% habitability on any planet. Robots can be given new traits via robo-modding and the template with the highest number of used trait points will be built by default. A different template can be specified for each planet.
The jobs a robot can have are limited by the highest robot technology researched. If an empire researches the Synthetics technology, robots can be given sapience, which lets them be affected by happiness and have ethics.
Robots without Citizen Rights require 50% less housing and amenities and do not need consumer goods. If a planet with sapient robots is captured by an empire that doesn't have the Synthetics technology, they lose their sapience, and if a planet with non-sapient robots is captured by an empire that has the Synthetics technology and does not have the Outlawed Artificial Intelligence policy, they are immediately given sapience.
|Available only with the Utopia DLC enabled.|
- It's possible to take the Synthetic Evolution ascension perk and turn all organic Pops and leaders into Synthetics.
- Hive Mind empires cannot build robots and will always purge all robots on their worlds.
|Available only with the Synthetic Dawn DLC enabled.|
- As long as an empire has the Artificial Intelligence policy set to Servitude there is a risk of them starting an AI rebellion.
- Machine Intelligence empires cannot build robots but they can use them if conquered from a regular empire or bought on the slave market. Robots in a Machine Intelligence empire can work all jobs and are not affected by happiness.
Purges represent the systematic elimination of specific pops or entire species from an empire and can be done on a per pop or species basis.
Targeted pop purging still requires applying the species-wide slavery at minimum and it is limited to a basic extermination, although without production penalty. Gestalt Consciousness can purge their pops of any composition freely, with exception of Bio-Trophies.
Species-wide purging is done by setting the species' citizenship to Undesirables. Gestalt Consciousness pops in empires of different authority are forced to be set as Undesirables too. Therefore, gaining planets from a Hive Mind empire means that the planet will be lost when it is empty of pop if there is not at least 1 Pop of the conquering empire's species on it. There are also four special cases:
- Pre-Sapients can only be purged if the Pre-Sapients policy is not set to Protected and are automatically purged if set to Extermination.
- Robots are automatically purged if the Robotic Workers policy is set to Outlawed.
- Synthetics can only be purged if the Artificial Intelligence policy is not set to Citizen Rights.
- Empires with the Evolutionary Mastery ascension perk can change the citizenship of hive mind pops to Assimilation, which prevents them from being purged.
Having any species-wide purge is a negative issue for Xenophile factions, aside from the case of Gestalt Consciousness pops and outlawed Robots.
Each planet has a purge timer and it progresses depending on the purge type. When the timer runs out, an undesirable pop on the planet will be killed or displaced. Opinion penalties will be applied, unless the purge type is Neutering or Displacement, or if the pop is Gestalt Consciousness drone, outlawed robot, or pre-sapient.
- All empires that has the same primary species as the purged pop will have their opinion to the purger reduced by −25 per pop and stack up to −1000.
- All other empires that has the Egalitarian or Xenophile ethic and doesn't allow species-wide purge will also have their opinion to the purger reduced by −5～10 per pop and stack up to −1000.
There are multiple types of purges available, determined by the Purge Type species right.
Pops from other empires may flee to escape purges, slavery, resettlement, crisis bombardment or as a result of land appropriation. Whether another empire is willing to accept those fleeing depends on its Refugees policy. Refugees will not head for empires where they have the Undesirables citizenship. Accepted refugee pops will get +20 happiness for 10 years.
Once refugees are generated they will head for any empire that will accept them with their Refugees policy following the following order:
- Habitability at least 70% and housing at least 1
- Habitability at least 70%
- Habitability at least 50% and housing at least 1
- Habitability at least 50%
- Habitability at least 20% and housing at least 1
- Habitability at least 20%
- Housing at least 1
- Any other planet