MTTR & MTBF Calculator

Type total repair hours, failures, and optional MTBF. 10 and 5 give 2.00 h. 4 and 2 give 2.00 h. 1.5 and 3 give 0.50 h. Typed times, not a CMDB.

A mean from typed repair hours. Not an ITIL report and not a live CMDB. SLO minutes sit on error budget.

Input data

Additional options (optional)

In this calculator, MTBF is treated as an input (average time between failures), not automatically derived from a fixed calendar window.

Results

Enter data and click Calculate.

How it works

The MTTR & MTBF Calculator in this calculator divides typed hours by the failure count. 10 h and 5 give 2.00 h. 4 h and 2 give 2.00 h. 1.5 h and 3 give 0.50 h. MTTR = repair sum / failures. MTBF is a typed input, not a calendar result. This is not a CMDB report.

Field mttr-repair is the hour sum. Field mttr-failures is the count. Field mtbf-hours in the examples is 500, 720, or 200, but the result stays MTTR. 10 / 5 = 2. 4 / 2 = 2. 1.5 / 3 = 0.5.

2.00 h does not come from Jira. 0.50 h is not a PagerDuty window. You type the times. The calculator does not read incidents and does not know ITIL.

Error budget next door counts minutes from an SLO. Uptime counts allowed downtime. Here 10 and 5 stay 2.00 h, a mean of typed times.

Type 10 and 5, then Calculate. MTTR is 2.00 h. A comma in 1,5 works. Zero failures do not divide. This is not a CMDB.

10 and 5 give 2.00 h. 4 and 2 give 2.00 h. 1.5 and 3 give 0.50 h. Another sum at 5 changes 2.00 h.

Formula

MTTR = repair hours / failures. MTBF is typed. Typed times, not a CMDB.

How to use

  1. Type repair sum 10 and 5 failures.
  2. Click Calculate. MTTR is 2.00 h.
  3. 4 and 2 give 2.00 h. 1.5 and 3 give 0.50 h.
  4. Typed times, not a CMDB report.
  5. SLO minutes sit on error budget.

10 h and 5 failures = 2.00 h

MTTR = repair sum / failures. 10 and 5 give 2.00 h. Typed times, not a CMDB.

MTTR
Hours over failures. 10 and 5 leave 2.00 h. Not Jira.
MTBF
A typed mtbf-hours value. 500, 720, or 200. Not a calendar result.
Calculator
Two required fields. 1.5 and 3 give 0.50 h. Typed times.

Examples

Example 1

  • 10 h repair
  • 5 failures
  • MTBF 500

2.00 h

What MTTR at 10 h and 5 failures? 2.00 h. Typed times, not a CMDB.

Example 2

  • 4 h repair
  • 2 failures
  • MTBF 720

2.00 h

What MTTR at 4 h and 2 failures? 2.00 h.

Example 3

  • 1.5 h repair
  • 3 failures
  • MTBF 200

0.50 h

What MTTR at 1.5 h and 3 failures? 0.50 h.

Related calculators

Error budget

Error Budget Calculator (SRE): SLO, period days, and used minutes.

Use calculator →

Uptime and downtime

Uptime and downtime: a percent.

Use calculator →

API Rate Limit

API Rate Limit Calculator: a limit, a unit, and a window.

Use calculator →

Cost Per Request

Cost Per Request Calculator: a price per million and a request count.

Use calculator →

Timezone Converter

Timezone converter: a date, a time, and zones.

Use calculator →

All IT calculators

Common questions

What MTTR at 10 h and 5 failures?

2.00 h. 10 / 5. Typed times, not a CMDB.

What about 4 h and 2 failures?

2.00 h. 4 / 2.

What about 1.5 h and 3 failures?

0.50 h. 1.5 / 3.

Is this a CMDB or ITIL report?

No. The calculator divides two typed numbers. It does not read incidents.

Is MTBF computed?

No. Field mtbf-hours is typed. The result stays MTTR.

Does a comma in 1,5 work?

Yes. 1,5 and 3 give 0.50 h.

What if failures are zero?

There is no MTTR, because we do not divide by zero.

Where do I count an error budget?

On error budget. Here 2.00 h from 10 and 5 stays.

Is 2.00 h an SLO?

No. It is a repair mean. SLO sits on the neighbour card.

Knowledge sources

The calculator counts bits, bytes or throughput from your numbers. Below are SI and bit definitions (NIST).

Page updated in 2026.

MTTR, MTBF, MTTA, and MTTD

MTTR (Mean Time To Repair) is the average time needed to restore service after a failure. MTBF (Mean Time Between Failures) is the average uptime between failures — here you supply it as an input (from history or an estimate), not as a value derived from a fixed calendar window. In practice, SRE teams often also break an incident down into MTTD (time to detect) and MTTA (time to acknowledge) — the MTTR this calculator computes covers the full repair duration, however it was measured.

Formulas

MTTR = total repair time ÷ number of failures. When you also provide MTBF, the calculator computes estimated availability: Availability = MTBF ÷ (MTBF + MTTR) — the standard steady-state availability model used in reliability analysis.

Availability targets vs failure cadence

Compare availability estimated from MTBF/(MTBF+MTTR) with common “nines” targets. Compact table below — for a fuller SLO downtime breakdown, see the Error budget calculator.

Availability targetDowntime / year (approx.)
99%~3.65 days
99.9%~8.76 hours
99.99%~52.6 minutes

How to reduce MTTR

  • Runbooks and automation for common repair actions (restart, rollback, failover) cut repair time more than faster detection alone.
  • Good dashboards and alerts with concrete context (not just "something is wrong") shorten diagnosis time — the largest chunk of MTTR is often spent just figuring out what broke.
  • Blameless post-mortems and tracked remediation items prevent the same long repair from recurring.

MTTR vs MTBF — what to fix first

Availability depends on both values, but improving them has different costs. Increasing MTBF (fewer failures) often requires architectural changes (redundancy, better testing) and is expensive. Reducing MTTR (faster repair) is usually cheaper and quicker to deploy — which is why many SRE teams invest in incident-response automation first, and fundamental reliability work second.

Examples

  • 10 hours of total repair time across 5 failures → MTTR = 2 hours.
  • MTTR = 2h, MTBF = 100h → availability ≈ 98.04%.
  • Same MTBF = 100h, but MTTR cut to 0.5h → availability ≈ 99.50% — showing how much impact shortening repair time alone can have.