MTBF and Availability Calculator
Mean time between failures, availability and total downtime from run hours and failure count.
Results
Availability
98.619
%
Mean time between failures
250.00
h
Unplanned downtime
28.00
h
What this tool does
Availability is the share of time a machine is ready to work, and it depends as much on how quickly it is repaired as on how rarely it breaks. Halving the repair time often buys more availability than doubling the time between failures.
Formula
MTBF = uptime time ÷ failures · A = MTBF ÷ (MTBF + MTTR)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
h | Run time | h |
f | Number of failures | — |
r | Mean time to repair | h |
A | Availability | % |
M | Mean time between failures | h |
D | Unplanned downtime | h |
Worked example
- Run time2000 h
- Number of failures8
- Mean time to repair3.5 h
- Availability98.619 %
- Mean time between failures250.00 h
- Unplanned downtime28.00 h
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.