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Backup storage

One full backup plus constant daily increments. No deduplication or additional full backups.

Quick answer · example

How much storage does an incremental backup need?

With 1000 GB initially, 5% daily change, 30 days, two copies and no compression, the model estimates 4900 GB: one full backup and 29 increments per copy.

Calculation assumptions

One full backup plus constant daily increments. No deduplication or additional full backups.

View the worked example ↓

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Result

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Formula and assumptions

GB = (G + G×change/100×(days−1))×copies/compression

One full backup plus constant daily increments. No deduplication or additional full backups.

All amounts use the same currency of your choice. These are estimates, not measurements or offers.

How to use this calculator

Size a repository with one initial full backup and constant daily changes. The change rate applies to the initial volume without compounding. Count only copies stored in the repository being sized.

Worked example

  1. 1000 GB with 5 % daily changes adds 50 GB per increment.
  2. 30 days has one full and 29 increments: 1000 + 29 × 50 = 2450 GB per copy.
  3. Two copies at compression ratio 1 require 2450 × 2 / 1 = 4900 GB.

Example result

Storage (GB)
4,900

Interpreting the result

Allow extra space for concurrent jobs and temporary files according to your product. Weekly or synthetic full backups need separate cycle calculations. Compression savings are not guaranteed.

Frequently asked questions

What value means no compression?

Use 1. A ratio of 2 halves the calculated volume; justify it with measurements.

Does it include deduplication?

No. Savings depend on data and product and should not automatically be added to compression savings.

Why 29 increments over 30 days?

The full backup occupies day one; increments start on day two.

References and method

NIST — GB / GiB · References and method