# MTTR Calculator

> Work out the mean time to repair from your own incident data.

Page: https://freecalculator.tech/tools/mttr-calculator
Last reviewed: 2026-09-16

## Formula

MTTR = Total repair time / Number of incidents repaired

- MTTR = Total repair time / Number of incidents repaired.
- Inputs used: Total time spent restoring service, Incidents repaired.
- Edge handling: Total time spent restoring service is required.; Total time spent restoring service cannot be negative.; Total time spent restoring service must be no more than 1000000000000.; Incidents repaired is required.; Incidents repaired cannot be negative..

## Inputs

- Total time spent restoring service
- Incidents repaired

## Worked example: 18.5 hours of restore work across 7 incidents

A mean over the incidents you counted. It is not a target repair time.
1. Start with Total time spent restoring service: 18.5, Incidents repaired: 7.
2. Apply the method: MTTR = Total repair time / Number of incidents repaired.
3. A mean over the incidents you counted. It is not a target repair time.

## Common questions

### Where does this formula come from?

Section 8.1.2.4 — mean time between failures is operating time divided by the number of failures; mean time to repair is total repair time divided by the number of repairs; inherent availability is MTBF / (MTBF + MTTR). See the source link on this page.

### What kind of calculation is this?

The arithmetic mean of the restore times of the incidents counted. 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. A mean hides the spread; a median or percentile answers a different question and is not calculated here.

### How do I use the MTTR Calculator?

Enter the required values for Total time spent restoring service, Incidents repaired. 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 MTTR Calculator use?

MTTR = Total repair time / Number of incidents repaired 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 MTTR 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.

## 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 mttr calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.

## Sources

- National Institute of Standards and Technology — https://www.itl.nist.gov/div898/handbook/apr/section1/apr124.htm

## Cite this page

- APA: Free Calculator. (2026, September 16). MTTR Calculator. https://freecalculator.tech/tools/mttr-calculator
- MLA: "MTTR Calculator." Free Calculator, 16 Sept. 2026, https://freecalculator.tech/tools/mttr-calculator.
- Link: MTTR Calculator — Free Calculator, https://freecalculator.tech/tools/mttr-calculator