MTBF and MTTR calculator
Mean time between failures, mean time to repair and inherent availability from three numbers: hours run, failures and repair hours.
Your numbers
Result
MTBF 300.0 hhours between failures, on average MTTR 4.0 hhours to repair, on average Inherent availability 98.7%MTBF ÷ (MTBF + MTTR) Failures per 1,000 hours 3.33The formula
MTBF = Operating hours ÷ Failures · MTTR = Repair hours ÷ Repairs · Availability = MTBF ÷ (MTBF + MTTR)
Count only the hours the machine ran, not calendar hours, and only failures that stopped it. With the defaults: 1,200 ÷ 4 = 300 hours MTBF, 16 ÷ 4 = 4 hours MTTR, and 300 ÷ 304 = about 98.7% availability, as in the MTBF guide.
Using the numberWhat to do with it
- A falling MTBF on one machine says something is wearing out; on a whole model, it points at the PM schedule or the operators.
- A rising MTTR usually means waiting, not wrenching: parts not on the shelf, a technician not free, or no history to diagnose from.
- This is inherent availability, which ignores waiting for parts and other delays. Real (operational) availability is lower; the availability guide explains the difference.
Guides behind this calculator
What is MTBF? What is MTTR? Equipment availabilityFleetZap Maintenance Pro (full CMMS)
Everything a maintenance team needs in one place: work orders and PM plus a parts store with purchasing, compliance and certificate tracking, multi-location assets with a full lifecycle, and the KPIs that prove it’s working.
- Parts & purchasing
- Compliance
- Assets & lifecycle
- Reports & KPIs
Good to know
How do you calculate MTBF?Divide total operating hours by the number of failures in the same period. A loader that ran 1,200 hours and failed 4 times has an MTBF of 300 hours. Use hours the machine actually ran, not calendar hours.
How do you calculate MTTR?Divide total repair time by the number of repairs. Four repairs that took 3, 5, 2 and 6 hours give an MTTR of 16 ÷ 4 = 4 hours.
How are MTBF and MTTR used to find availability?Inherent availability is MTBF ÷ (MTBF + MTTR). With 300 hours MTBF and 4 hours MTTR, availability is 300 ÷ 304, about 98.7%. It leaves out waiting for parts and other delays, so real availability is usually lower.
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