What is the min space for a cat to live ok in?

What is the minimum space the cat can live in? I know people whose cat lives in a room that is only about 11 square meters. We have two cats and they have about 20 square meters each (they don't get along so one has the kitchen and the living room) the other two small bedrooms and a small corridor.
One bedroom is 7 sq meters and the corridor is 4 and the other bedroom is under 10 sq meters.
The living room is about 13-14 sq meters and the kitchen I think about 6 and this is not floor space as we have furniture and appliances. Cats seem happy though

I believe long as the cats are given exercise and things to play and climb on, they can be happy in just about any space. If you can add shelves or something for them to climb on they'll be happier.. they like the height!

Correction - these are more correct dimensions

Small room 7.5 square meters

Bigger bedroom around 11 s meters

Corridor 3.5 square meters

So one cat has 22 s meters

Living room 28 square meters

Kitchen  3.6 sq meters but very full with stuff

About 30 sq meters for Snowy but most of the time he is in the living room as the kitchen he likes to go for garbage and other places so we lock it when we cant watch him. Or fight with our outside cat through kitchen window! they bash the glass from both ends and we are worried they would break it or Snowy fell into the sink with dishes when doing it so we dont let him there at the moment.. This cat is named Jack and we befriended and look after now his owner passed away. he often sleeps in another room ie the 11 s meter one so Tabby only has 11 meters for himself. Similarly to my relatives cat. But I was worried this was too small. But Jack doesnt live there just comes to sleep for a few hours and to eat and goes out again. So Tabby has the bigger room a lot of the time as well

But I understand what you mean - i will be adding a few shelves and a cat tree. One has his small tree at the moment and the other an old chair to scratch but they both like climbing, snowy sometimes goes on the kitchen cupboards and sleeps near the ceiling there

I just worry they get bored with small space like this

Vertical space is more important to cats than horizontal spaze. As long as you have something for the cats co climb on and be elevated off the floor, it doesn't matter how small your home is. Beds, sturdy bookcases and furniture, window shelves, cat trees and furniture, etc.