Backup Retention Storage Planner
Estimate retained full/incremental/differential backup storage while preserving the full backup needed by the earliest restore point.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Determine the earliest retained daily restore point, keep its required full-chain base and calculate the logical size of all retained backup objects. Apply entered compression, copies and allowance.
Incremental size=full size×daily change; differential size=full size×min(1,days since full×daily change)
Worked example
Full size 100, full every seven days, current day 8 and retention two days retain day 7 full plus day 8 incremental. At 10% daily change and no compression, this is 110 units.
Assumptions and input details
Constant full logical size and daily changed fraction; differential cumulative change is capped at full size without estimating block overlap. Compression is applied to each object; no cross-point deduplication. Incremental chains can retain objects older than the earliest requested restore point. 0–3650 day indices and up to 3650 restore points. This performs no backups or deletion.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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