Bug Escape Rate Calculator

Work out bug escape rate instantly with clear inputs, formula shown and shareable results.

About Bug Escape Rate Calculator

Defect removal efficiency is the share of all defects caught before release, and its complement is the escape rate. Industry benchmarks put good practice around 85 to 95 percent removal efficiency. It is a better quality signal than raw defect counts because it normalises for how buggy the code was in the first place.

Formula

Escape rate

escape rate = production defects / (pre-release + production defects); removal efficiency = 100% - escape rate; density = total defects / KLOC

Worked example

With the default values below, Bug Escape Rate Calculator returns Defect escape rate of 12.41%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Defects found before releaseminimum 0: 240
Defects found after releaseminimum 0: 34
Size of the releaseminimum 0.01 KLOC: 45 KLOC
Cost per production defectminimum 0: 3,200

Results

Defect escape rate: 12.41%
Defect removal efficiency: 87.59%
Defect density: 6.09 defects/KLOC
Cost of escaped defects: $108,800

Step by step

1Values used
2Escape rate
3Defect escape rate= 12.41
4Defect removal efficiency= 87.59
5Defect density= 6.09 defects/KLOC
6Cost of escaped defects= 108,800

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 escape rate should be targeted?

Below 10 to 15 percent for mature teams. The absolute number matters less than the trend and than which test stage is missing the defects.

Should severity be weighted?

Yes, for decisions. One escaped data-corruption defect matters more than twenty cosmetic ones, so track severity-weighted escape rate alongside the raw figure.