An explicit estimate
Backup space planner
Plan room for one new full copy. Use measured sizes where possible, then test a less comfortable growth assumption.
Your new-copy budget
Prefilled values are a hypothetical example. Replace them with your own measurements. All capacity fields use decimal GB.
Required space budget
This is an estimate for one destination, not a safe-to-delete recommendation.
Use the estimate to ask a better question
If the budget exceeds free space, investigate the destination and retention policy. Do not delete the only original to make a number turn positive. Map independent copies first.