Right Sizing Savings Calculator

Work out right sizing savings instantly with clear inputs, formula shown and shareable results.

About Right Sizing Savings Calculator

Right-sizing scales the instance to the target utilisation, so the cost ratio is current utilisation divided by target. Because cloud instance families double in size and price at each step, the practical move is a whole number of steps down — each step halves both capacity and cost, so a workload at 14 percent utilisation can usually drop two sizes.

Formula

Right-sizing

size ratio = current utilisation / target utilisation; new cost = current cost x ratio; steps down = floor(log2(1 / ratio))

Worked example

With the default values below, Right Sizing Savings Calculator returns Monthly saving from right-sizing of $6,261.82. Change any input above and every figure here is recalculated in your browser.

Inputs used

Instances to right-sizeminimum 1: 60
Current average CPU utilisationaccepts 0.1–100 %: 14 %
Target utilisationaccepts 1–100 %: 55 %
Monthly cost per instanceminimum 0: 140

Results

Monthly saving from right-sizing: $6,261.82
New monthly cost per instance: $35.64
Cost reduction per instance: 74.5%
Instance size steps to drop: 1

Step by step

1Values used
2Right-sizing
3Monthly saving from right-sizing= 6,261.82
4New monthly cost per instance= 35.64
5Cost reduction per instance= 74.5
6Instance size steps to drop= 1

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 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

Should memory be considered as well as CPU?

Yes, and it often blocks downsizing. An instance at 14 percent CPU but 80 percent memory cannot be halved without changing to a memory-optimised family.

What about burst headroom?

Right-size against the sustained peak, not the average, and keep enough headroom for the largest expected spike. Targeting 55 percent leaves roughly 80 percent of a step in reserve.