how much space is required to upgrade to Big Sur

How to upgrade to macOS Big Sur - Apple Support

"If upgrading from macOS Sierra or later, macOS Big Sur requires 35.5GB of available storage to

upgrade. If upgrading from an earlier release, macOS Big Sur requires

up to 44.5GB of available storage. To upgrade from OS X Mountain Lion,

first upgrade to OS X El Capitan, then upgrade to macOS Big Sur."

45GB worst case.

Richard Thomas wrote:

How much space is required to upgrade my MacBook Pro, Mac OS Catalina, to Big Sur?

What was wrong with the response I provided March 17?