How to Calculate MTBF and MTTR

MTBF (Mean Time Between Failures) and MTTR (Mean Time To Repair) are two core metrics in maintenance management: one measures equipment reliability, the other measures how fast the maintenance team responds. This article explains how to calculate both, with examples, and how to use them in maintenance decisions.

How is MTBF calculated?

MTBF is total run time divided by the number of failures in that period:

MTBF = Total Run Time ÷ Number of Failures

Example: a machine ran 600 hours in a month and failed 4 times during that period, so MTBF = 600 ÷ 4 = 150 hours. That means the machine fails, on average, every 150 hours. The higher the MTBF, the more reliable the equipment.

How is MTTR calculated?

MTTR is total repair time divided by the number of failures in that period:

MTTR = Total Repair Time ÷ Number of Failures

Example: if repairing those same 4 failures took a total of 8 hours, MTTR = 8 ÷ 4 = 2 hours. The lower the MTTR, the faster the team’s response/repair speed.

The precondition for calculating these correctly: accurate data

For MTBF and MTTR to be meaningful, fault start/end times and run hours need to be recorded consistently. On paper forms this data is often missing or approximate, which makes the calculation unreliable. In a CMMS, a fault record’s open/close timestamp is captured automatically, so MTBF/MTTR calculations are based on accurate data. We covered how a CMMS works in general in our what is a CMMS article.

How to use these metrics in maintenance decisions

• Equipment with low MTBF (frequent failures) should move up the priority list for renewal/overhaul.
• Failures with high MTTR (long repair times) should be examined for spare-parts availability or technician skill gaps.
• Comparing both metrics machine-by-machine gives you data-backed grounds for investment decisions.

MTBF/MTTR tracking in bakimo

bakimo automatically captures fault open/close timestamps, so it reports MTBF/MTTR analytics per machine — this feature is available on Pro and higher plans. See details on our pricing page.

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