CPU Steal Time Impact Calculator

Work out cpu steal time impact instantly with clear inputs, formula shown and shareable results.

About CPU Steal Time Impact Calculator

Steal time is CPU the hypervisor gave to another guest while your vCPU was runnable, so it directly reduces available capacity and you pay for it regardless. Nine percent steal on eight vCPUs is effectively 7.3, and it also inflates apparent utilisation because the same work is squeezed into less real CPU time.

Formula

Steal impact

effective vCPUs = allocated x (1 - steal); wasted cost = hourly rate x steal x 730; real utilisation = demand / (1 - steal)

Worked example

With the default values below, CPU Steal Time Impact Calculator returns Effective vCPUs available of 7.28. Change any input above and every figure here is recalculated in your browser.

Inputs used

Steal timeaccepts 0–100 %: 9 %
vCPUs allocatedminimum 1: 8
Workload CPU demandaccepts 0–100 %: 65 %
Instance hourly costminimum 0: 0.38

Results

Effective vCPUs available: 7.28
vCPU capacity lost to steal: 0.72
Monthly spend on stolen cycles: $24.97
Real utilisation of available capacity: 71.4%

Step by step

1Values used
2Steal impact
3Effective vCPUs available= 7.28
4vCPU capacity lost to steal= 0.72
5Monthly spend on stolen cycles= 24.97
6Real utilisation of available capacity= 71.4

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

What steal time is acceptable?

Below 2 to 3 percent is normal on shared instances. Sustained double-digit steal means the host is oversubscribed and you should migrate or move to dedicated capacity.

Do burstable instances show steal?

They show it once CPU credits are exhausted and the instance is throttled to its baseline, which is one of the clearest signals that the instance type is wrong.