Change Failure Rate Calculator
Work out the share of production changes that caused a failure.
In short
Formula: Change failure rate = Failed changes / Changes released to production
What this calculator does
The DORA change failure rate, using the user's own written definition of a failed change consistently across both counts.
Use it to turn Changes released to production, Changes that caused a failure into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this professional & industry calculation.
Inputs and what they mean
- Changes released to production
- — All changes released in the period..
- Changes that caused a failure
- — Changes that led to degraded service needing a fix, rollback or patch..
How to use it
- Enter your own figures — the calculator never fills in a rate, price or benchmark for you.
- Press Calculate to see the result.
- Read the formula, variables, assumptions and source below the result before you rely on it.
Formula
Change failure rate = Failed changes / Changes released to production.
Inputs used: Changes released to production, Changes that caused a failure.
Edge handling: Changes released to production is required.; Changes released to production cannot be negative.; Changes released to production must be no more than 1000000000000.; Changes that caused a failure is required.; Changes that caused a failure cannot be negative..
Worked example
7 failures out of 86 changes
- Start with Changes released to production: 86, Changes that caused a failure: 7.
- Apply the method: Change failure rate = Failed changes / Changes released to production.
- The measured rate for your period; no acceptable rate is implied.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Inputs outside the supported range are rejected rather than forced into a result.
- The result depends on the values you enter for this change failure rate calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Reference: DevOps Research and Assessment, Google Cloud — DORA metrics: the four keys
Last reviewed:
Common questions
Where does this formula come from?
Deployment frequency is deployments to production divided by the length of the period; change failure rate is the share of changes to production that cause degraded service requiring remediation; failed deployment recovery time is the time taken to restore service after such a change. See the source link on this page.
What kind of calculation is this?
The share of production changes that led to degraded service needing remediation. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
What are its limits?
Arithmetic over the figures entered — it cannot tell whether the underlying monitoring, incident records or change records are complete. A mean over a short period, or over few events, is a weak description of behaviour. Sensitive to how a failure is defined; two teams with different definitions cannot be compared.
How do I use the Change Failure Rate Calculator?
Enter the required values for Changes released to production, Changes that caused a failure. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Change Failure Rate Calculator use?
Change failure rate = Failed changes / Changes released to production The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone. Check the formula, example, and limitations on this page before using the result for a real professional & industry decision.
Can the Change Failure Rate Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Formula, source and verification
The share of production changes that led to degraded service needing remediation.
The question it answers: What is our deployment rate, what share of changes fail, and how long does recovery take?
The formula
Change failure rate = Failed changes / Changes released to production
- f — Failed changes
- (count). Changes that caused degraded service requiring a fix, rollback or patch.
- c — Changes released
- (count). All changes released to production in the period.
Units: Counts in, percentage out.
What kind of calculation this is
Deterministic formula. The same inputs always give the same answer. The maths is fixed and does not depend on judgement.
Method
The DORA change failure rate, using the user's own written definition of a failed change consistently across both counts.
Assumptions built into the result
- Mathematical: The figures entered all cover the same measurement period.
- Mathematical: Incidents, changes and requests are counted consistently with the definition the team has written down.
- Mathematical: The same definition of failure is applied to every change counted.
Figures this calculator will never guess for you
- No target, benchmark, industry average or performance band is supplied for any figure.
- A definition is never presented as a goal: the availability formula is not an availability target, and the change failure rate formula is not an acceptable failure rate.
- No acceptable failure rate is stated and no performance band is applied.
Limitations
- Arithmetic over the figures entered — it cannot tell whether the underlying monitoring, incident records or change records are complete.
- A mean over a short period, or over few events, is a weak description of behaviour.
- Sensitive to how a failure is defined; two teams with different definitions cannot be compared.
Source and version
- Standard or reference
- DORA metrics — the four keys — DORA (Deployment frequency is deployments to production divided by the length of the period; change failure rate is the share of changes to production that cause degraded service requiring remediation; failed deployment recovery time is the time taken to restore service after such a change.)
- Published source
- DevOps Research and Assessment, Google Cloud — DORA Metrics Guide
- Formula version
- Version 1
- Verification
- Reviewed against the cited source on
- How much weight the source carries
- Academic
- Applies to
- Currency
- The result is a ratio or index, so it does not depend on currency.
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