I'm trying to backup Documents folder only. Folder contains 10GB. Entire User folder is about 50GB.

When trying to exclude all folders (included hidden ones ), I get to 48GB of backup storage required.

What do I do wrong ?

  • Some really smart people have been stumped by this, so I’m sure TM over counts in some cases. apple.stackexchange.com/questions/363939/…
    – bmike
    Commented Oct 3, 2020 at 20:18
  • It is usually recommended for your backup drive to be 3x the volume of the data you want to backup: that should include sufficient duplication for those files that change. Even a 250 Gb disk would give you 5x the size. So I'd suggest backing up more, rather than less.
    – benwiggy
    Commented Oct 3, 2020 at 21:08
  • Also, is it possible that you have a backup of an iPhone or iPad on your Mac? That's likely the source of the size difference. At worst, you could exclude the ~/Library/Application Support/MobileSync/Backup folder.
    – benwiggy
    Commented Oct 3, 2020 at 21:11
  • @benwiggy regarding size- it is not what I’ve asked. Regarding possible backups- all directories are marked off including hidden, and no subdirectories present below Documents
    – guyd
    Commented Oct 4, 2020 at 11:20

1 Answer 1


The estimates are often off to be conservative, make sure enough space is there to not run out if the estimate is not perfect. Just exclude every folder and allow a token empty one to back up. After several intervals, the estimate will be better and you can add documents back by removing it from the exclusion list.

  • I'm trying to backup to NAS, using WiFi. It would take forever....
    – guyd
    Commented Oct 3, 2020 at 20:05
  • 1
    Aah, I’ll remove that. My main comment stands, reduce your backup selection and incrementally relax it if you need to squeeze. Perhaps a different tool would be better to backup your data like arq or borg if you’re setting up servers and network shares. @Guy.D
    – bmike
    Commented Oct 3, 2020 at 20:12

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