Research slots in HOI4

Most states in Hearts of Iron can have up to 5/6 slots, but itself start with fewer slots can be sometimes difficult. Let’s take a look at how to get more research slots and open up research on the technologies you need.

Slots at the start divided by countries

I have prepared a list of research slots below. The base is solid and you can’t do anything about it, however, you will always be able to open additional slots in national focus. Let’s take a look at each option:

4 opened and 2 researchable by national focus

  • USA
  • democratic Germany (if you have DLC Waking the Tiger)

4 opened and 1 researchable by national focus

  • German Reich
  • Italy
  • Japan
  • United Kingdom

3 opened and 2 researchable by national focus

  • France
  • Soviet Union (basically 3+1 but if you go The Right Opposition, you could have 3+2)
  • Other European countries
  • Canada (basically 3+1 but if you have independence 3+2)

2 opened and 3 researchable by national focus

  • Other non-European countries
  • Luxembourg
  • Portugal
  • Albania

How to get more research slots?

As I tried to point out above, adding a research slot can be done by research. This usually looks like the following picture and can be found in the more advanced parts of the national focus tree. That means you don’t have to rush, because you will gradually get to the research slots as the game goes on.

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