Why does some of my games have 40gb 60gb 50gb updates .

i have seen where a lot of games require massive changes and they download near enough the entire game again to replace the altered files, i have had a 45GB game update with 40GB of data and the game still only takes 45GB of space. xbox is weird like that.

some games have to update and replace a lot of files, it does not take extra space once completed, also if you cancel an update it then has to download the entire game again as it cannot verify the files.

Not sure I understand this response. If a game starts out at 50gb you install that 50gb. If an updates comes and its 20gb then you will have to install another 20gb. It just depends on what type of game it is and what kind of bug fixes or add ons to the game. Like a little game like UNO, thats probably well under 10gb and I only expect my updates to be a min and all under 1gm the most.

My update showed as 40GB my friends update was only 4GB. Other times i have seen 60GB on games like call of duty black ops 4. It shouldnt be that large of an update especially since it was bigger than the game itsef.

[quote user="Lei Fang DOAX3"]Given that you only have 324 GB of actual usable storage space,[/quote]364.9GB. It's listed on the dashboard.

what is the average size of an Xbox One game when it is installed into the HDD.

There isn't an "average".
An estimate won't help. Some games are 50GB, some are 40GB, some are 36, some are 16, some are less than 1GB.

Using, say, 20GB as an "average" doesn't help when the game you want to buy requires 50GB and your storage device is down to 40GB free.