Stellaris’s 3.0 update changed the mechanics of pop growth. Before 3.0, you could grow pops easily forever, even if your planet was massively overcrowded. Things are a little bit different now. Let’s start by understanding how Planet Capacity works.
What is Planet Capacity?
Planet Capacity is a value based on the total housing of a planet, and it can also be affected by cleared blockers or undeveloped districts. You can check your planet’s Planet Capacity by hovering over the “Planet Size” value on the planet screen.
As you can see, this planet’s total capacity value is 43. You can increase a planet’s total capacity by building City Districts.
How to Use Planet Capacity to Grow Pops Faster in Stellaris
Now that you know what Planet Capacity is, you’re ready to start using it to grow pops faster. The first thing you want to make sure is that you have at least around 22 pops.
Note that this doesn’t work when you’ve only have a few pops. You need to have a few pops to begin with.
With this many pops, you can increase your planet capacity to 100 and this will maximise the bonus to pop growth that you get. Even better if you have 25 pops, then you only need 80 planet capacity.
How to retain the pop growth bonus
So, you’ve managed to get the maximum bonus to pop growth (3), now, how do you retain that bonus? You will start losing that bonus as you grow more pops, so it stands to reason that you should resettle these pops to a different planet. The caveat is that resettling pops can cost you Influence, which can make the process very costly. The only other way to achieve this is by leaving unemployed pops. Unemployed pops will now resettle automatically to other planets with free jobs, but…
Pop resettlement is based on chance, and you can increase your chances by building a Transit Hub module on the system’s starbase, which will double the chance of automatic resettlement. Another thing to keep in mind is that you’re building robots that don’t have full citizenship, you will have to resettle those manually since they have migration controls enabled.