Snapshot Space Usage Calculator

Work out snapshot space usage instantly with clear inputs, formula shown and shareable results.

About Snapshot Space Usage Calculator

Copy-on-write snapshots consume space in proportion to changed blocks, not volume size, so a 500 GB volume changing 4 percent daily accumulates about 20 GB per daily snapshot. Retaining fourteen of them costs 280 GB — over half the volume — which is why snapshot retention on a write-heavy volume needs explicit capacity planning.

Formula

Snapshot space

space per snapshot = volume x daily change rate x (interval / 24); total = space per snapshot x snapshots retained

Worked example

With the default values below, Snapshot Space Usage Calculator returns Space consumed by snapshots of 280.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Volume sizeminimum 0.001 GB: 500 GB
Daily change rateaccepts 0.001–100 %: 4 %
Snapshots retainedminimum 1: 14
Snapshot intervalminimum 0.1 h: 24 h

Results

Space consumed by snapshots: 280.00 GB
Space per snapshot: 20.000 GB
Total space including the live volume: 780.00 GB
Snapshot overhead relative to the volume: 56.0%

Step by step

1Values used
2Snapshot space
3Space consumed by snapshots= 280.00 GB
4Space per snapshot= 20.000 GB
5Total space including the live volume= 780.00 GB
6Snapshot overhead relative to the volume= 56.0

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why do snapshots sometimes consume more than expected?

Because overwriting the same block repeatedly creates a new copy each snapshot period, and because copy-on-write granularity means a small change can copy a whole block.

Are snapshots a backup?

No. They usually live on the same storage, so a device failure or a full-volume corruption takes them with it. They are for fast rollback, not disaster recovery.