Snapshot Growth Calculator
Forecast how an incremental snapshot chain grows as the protected volume itself grows month over month.
About Snapshot Growth Calculator
A snapshot chain reaches a steady state where it holds one base copy plus one delta for every day still inside the retention window, so the footprint is the written data multiplied by a factor set by retention and change rate. Growing the source compounds that whole footprint, which is why a 5% monthly increase becomes roughly 1.8x in a year rather than 60%. The price is a user-supplied list price to confirm on the AWS EBS pricing page for your region. Snapshot spend is the line item that grows without anyone changing a setting, and seeing the compounding early is what justifies shortening the retention window before the bill forces it.
Formula
Snapshot Growth
footprint(month m) = written GiB x (1 + monthly growth)^m x (1 + (retention days − 1) x daily change rate).
- chain factor
- Multiplier the retention window adds on top of the base copy
- monthly growth
- Compound growth rate of the written data
Worked example
With the default values below, Snapshot Growth Calculator returns Snapshot Footprint at the Horizon of 1,206.8. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Written data on the volume todayminimum 0 GiB
- 400 GiB
- Daily change rateaccepts 0–100 %
- 2 %
- Snapshot retention windowaccepts 1–3,650 days
- 35 days
- Monthly growth of the written dataaccepts -50–100 %
- 5 %
- Forecast horizonaccepts 1–120 months
- 12 months
- Snapshot priceminimum 0 USD per GB-month
- 0.05 USD per GB-month
Results
- Snapshot Footprint at the Horizon
- 1,206.8 GiB
- Snapshot Footprint Today
- 672.0 GiB
- Growth Multiple
- 1.80 x today
- Cost in the Final Month
- $60.34
- Cumulative Cost Over the Horizon
- $561.56
- Average Monthly Cost
- $46.80
Step by step
- 1Values used
- 2Snapshot Growth
- 3Snapshot Footprint at the Horizon= 1,206.8 GiB
- 4Snapshot Footprint Today= 672.0 GiB
- 5Growth Multiple= 1.80 x today
- 6Cost in the Final Month= 60.34
- 7Cumulative Cost Over the Horizon= 561.56
- 8Average Monthly Cost= 46.80
Assumptions and limits
- The result is derived only from the 6 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 2 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
How is Snapshot Growth calculated?
footprint(month m) = written GiB x (1 + monthly growth)^m x (1 + (retention days − 1) x daily change rate). A snapshot chain reaches a steady state where it holds one base copy plus one delta for every day still inside the retention window, so the footprint is the written data multiplied by a factor set by retention and change rate. Growing the source compounds that whole footprint, which is why a 5% monthly increase becomes roughly 1.8x in a year rather than 60%. The price is a user-supplied list price to confirm on the AWS EBS pricing page for your region.
Why does Snapshot Growth matter?
Snapshot spend is the line item that grows without anyone changing a setting, and seeing the compounding early is what justifies shortening the retention window before the bill forces it.
What values do I need to enter?
This calculator takes 6 inputs: Written data on the volume today, Daily change rate, Snapshot retention window, Monthly growth of the written data, Forecast horizon, Snapshot price. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
Does a longer retention window cost proportionally more?
No, less than proportionally. Extending retention adds one daily delta per extra day, not another full copy, so going from 7 to 35 days at a 2% change rate roughly grows the footprint from 1.12x to 1.68x the written data.