Quick guide
How to use this calculator
- Choose the real storage, transfer, media, backup, or archive task first, then enter only the measurements and assumptions that belong to that workflow.
- Keep bits and bytes, decimal SI and binary IEC prefixes, rates, durations, counts, reserves, efficiency, overhead, compression, and retention conventions explicit.
- Use the companion outputs to reconcile the scenario. Where actual system behavior is unknown, enter measured values or retain the stated limitation instead of treating a plan as a guarantee.
Calculation method
How the backup storage and retention planner works
Turn a retention policy into a transparent storage scenario without assuming deduplication, compression, immutable-storage overhead, or a vendor billing model.
For each retained generation, projected dataset = current dataset × (1 + growth)^generation; payload = one full plus entered incremental count × changed-data percentage. Sum generations, multiply by copies, then add the reserve.
Worked example
Backup Storage and Retention Planner example
Four retained generations of a 2 TB dataset, six 5% incrementals per generation, 2% growth, two copies, and 15% reserve require about 24.65 TB planned capacity.
For each retained generation, projected dataset = current dataset × (1 + growth)^generation; payload = one full plus entered incremental count × changed-data percentage. Sum generations, multiply by copies, then add the reserve.
Supported inputs
Precision and limits
Digital-system boundary
Changed-data percentage is applied independently to each incremental as a planning assumption. Restore chains, deduplication, compression, synthetic fulls, snapshots, immutability, encryption, metadata, failures, egress and provider billing are excluded.
Units and precision
One byte is eight bits. Decimal kB, MB, GB and TB use powers of 1,000; binary KiB, MiB, GiB and TiB use powers of 1,024. Calculations retain working precision and round only for display.
Category ownership
This calculator handles neutral information quantity, transfer, storage, media-payload, compression, backup, RAID, or archive arithmetic. Live speed tests, IP addressing, packet engineering, current vendor pricing, security analysis, and physical display sizing belong to other tools.
Privacy
File names and contents are never requested. Entered quantities and results stay in this browser and are not sent to analytics or third parties.
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