Find individual users' backup size in Time Capsule I'm the administrator of a 2 TB Time Capsule, to which my co-workers connect via individual accounts. I recently noticed a sudden jump in usage — from ~1 TB (0–1 over the course of 8 months) to ~1.5 TB (1–1.5 in a span of 2 weeks). My guess is that one of them downloaded experimental data files (which don't need to be backed up, as they're done so elsewhere) and stored them locally during those two weeks and accidentally backed them up, thus contributing to the bloat.

Is it possible for me to find out the sizes of these users' backups, so that I can then instruct them to use tmutil to remove only the specific backups with the huge data files? I do not have access to the contents of their backups (at least, not easily and I want to either).
You'll want to get a tool like BackupLoupe to introspect each backup event to locate the largest files stored on each interval (or search across all backups to find large folders and files).

You could also use a command line tool like tmutil compare or du -sm /whatever/* to calculate sizes and changes - but a graphical tool with searching ability even when the volume is not mounted is far superior for the task of finding large users of space on a Time Machine volume.