Do App updates replace the initial app size, or they just add up to it?

[venom0706]

For example, if I have an app that is 6 MB, and I see an update on the Google Play store, which is 4 MB, will the size of the app on my phone become 10 MB (the initial + the update), or it will become 4 MB (the update will be a newer version of the app that will replace the old one)? If the first scenario occurs, wouldn't that fill up my smartphone's storage really fast? It seems that the Google Play apps release updates almost every 2-3 days. I now that I can update them whenever I want, but still... I am just curious. Thank you.

 

[rgd1101]

could be either, depend on what the update is doing, but mostly just add some.

 

[LOLOLzers123]

It is just adding 4mb, so if the app was 6mb and the update is 4mb the apps new size would be 10mb