About the MTBF & MTTR Calculator
Mean time between failures (MTBF), mean time to repair (MTTR) and availability from operating data.
Also known as: mean time between failures, mttr calculator, maintenance interval, reliability calculator.
How to use this calculator
- Enter total operating hours, number of failures, total repair time (hours).
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Review the breakdown shown under the main result.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
MTBF = operating hours ÷ failures · Availability = MTBF ÷ (MTBF + MTTR)
Worked example
Using the values pre-filled in the calculator above:
- Total operating hours = 4,380
- Number of failures = 12
- Total repair time (hours) = 36
the calculator returns:
- MTBF: 365 hours
- MTTR: 3 hours
- Availability: 99.185%
- Failure rate: 0.00274 per hour