Software update
My MacBook Air is running Mojave 10.14.6 and I'm getting notifications to install Big Sur. But it's 12 GB and my Mac has only 4.
Can I just ignore?
MacBook Air 13″, macOS 10.14
Question marked as
You don't have to upgrade to Big Sur, as Mojave will continue to receive security and browser updates from Apple until Fall 2020. With 4GB of installed RAM, you won't be happy with application performance after upgrading to Big Sur. I have macOS 11.2.1 running on a 2014 MacBook Air with 4GB RAM, and it is usable, just slow.
Do not confuse RAM memory with drive storage. Click once on. your Macintosh HD icon on your Desktop. Press option+command+i to open a Get Info panel. What does the Available amount tell you in GB about your drive storage? You would need 35.5 GB of available storage before you can upgrade to Big Sur.