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Versioned copies

Computer Backup Storage Planner

Size a separate backup target for one or more computers, including changed-file versions and a practical reserve.

Backup assumptions

Use used data, not the marketed size of each internal drive. The estimate applies to Windows, macOS, or a mixed group.

Data and retention
TB

%

months

years

Used for input validation and your planning cadence.

%

What the estimate includes

The planner reserves space for an initial full backup and a conservative share of changed data retained as versions. It does not assume deduplication, compression, or a vendor-specific snapshot engine.

Use the result safely

A backup target should be separate from the computer and separated from the primary storage array. Test a restore of representative files and keep an offsite or otherwise independent copy for important data.

Related tools

For a complete household topology, start with the Home Storage & Backup Planner. See the NAS sizing guide for capacity and protection context.