I am trying to update my MacOS to Big Sur, but when I have to install it, it always says there is no enough space in the selected volume... an additional 19.22 GB is required. Does this new app really require that much space?

Hi Borjok,

It sounds like you're having trouble upgrading due to a lack of available storage and we can help.

This is a normal amount of space to be required to install a macOS upgrade.

If you need help freeing up storage space, follow this guide:

How to free up storage space on your Mac - Apple Support

Take the steps here to upgrade to macOS Big Sur:

How to upgrade to macOS Big Sur - Apple Support

Good luck.

Thanks for using the Apple Support Communities.

The actual Big Sur upgrade takes about 1 hour (in my own experience). However, it is much larger than previous macOS upgrade installations, and does require 35+ GB of available storage if upgrading from High Sierra 10.13.6, and 45GB+ if upgrading from Sierra (10.12.6) or earlier.