Backup Retention Cost Calculator accuracy and testing

Formula source

• Retained GB = (full backup GB + daily changed GB * retention days) / compression ratio * copy count. Monthly cost = retained TB * price per TB-month.

Test cases

Known limitations

• This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
• Use the result as a planning estimate unless the calculator page states a stricter purpose.

Assumptions

• Pricing is user-entered because storage, backup, and archive plans vary.
• The model uses a simple full-plus-change retention estimate, not a vendor-specific deduplication engine.
• Calculations run locally in your browser and are for planning only.

Unit handling

• Storage Vendor Preset accepts one of the configured options.
• Full Backup Size accepts values in GB.
• Daily Changed Data accepts values in GB/day.
• Retention Period accepts values in days.
• Compression Ratio accepts values in :1.
• Billable Copy Count accepts numeric values.
• Storage Price accepts values in $/TB-mo.
• Estimated Monthly Cost is displayed as currency.
• Retained Storage is displayed in TB.
• Estimated Annual Cost is displayed as currency.
• Raw Retained Data is displayed in GB.

Rounding rules

• Number displays use up to 2 decimal places in the calculator UI.
• Currency outputs are displayed with standard US dollar formatting.
• Input precision follows configured step values where provided.

Version history

Change log