How many gigabytes is an os?

[GameableXP]

So i'm getting an ssd soon and I'm putting the os on it. The thing is, I don't know how many gbs for the ssd i will need. Some say that a 32 gb ssd can have the os on it and have some extra room, but others say that a 120gb ssd will not be enough. please tell me the recommended space for an ssd. (I used to have windows 7 home premium but upgraded to windows 10, just in case it takes more room or something)

 

[Jasjar]

An os is about 20gb without updates. 120 gb should be enough space.

 

[USAFRet]

Do not buy a 32GB. Even if you can find one.
Don't buy a 64GB.
A 120GB will work, but a 250GB is a much better size vs price ratio.

Actually, Win 10 takes up less space than Win 7, simply due to the years of built up updates in Win 7.

I have a small Asus Transformer, with a 32GB drive. It just barely works with Win 10.

 

[USAFRet]

An os is about 20gb without updates. 120 gb should be enough space.

Without updates, it is pretty useless.

A clean install, after all existing updates are run:
Win 7 ~40-45GB
Win 8.1 ~35GB
Win 10 ~25GB

Now, we also have to leave approx 10-15% free.
So with a 120GB drive, you actually have about 85GB that you can actually use. The OS and 1 game.