How to Calculate MTBF and MTTR for Your Equipment

Divide total operating time by the number of failures to get MTBF. Divide the total time from each failure until the asset is back in service, including waiting for parts and people, by the number of failures to get MTTR. MTBF and MTTR show how reliable your equipment is and how efficiently your team responds to failures.

What is MTBF?

MTBF (Mean Time Between Failures) measures the average time between equipment breakdowns. A higher MTBF means more reliable equipment.

How to Calculate MTBF

MTBF = Total Operating Time / Number of Failures

Example: A pump runs for 2,000 hours over 6 months and fails 4 times.

MTBF = 2,000 hours / 4 failures = 500 hours

This means the pump averages 500 hours of operation between breakdowns.

What MTBF Tells You

High MTBF — Equipment is reliable; your PM program is working
Low MTBF — Equipment fails frequently; investigate root causes
Declining MTBF — Equipment is degrading; consider replacement or increased maintenance
Improving MTBF — Your maintenance improvements are paying off

What is MTTR?

MTTR (Mean Time To Repair) measures the average time from a failure until the equipment is back in operation, including the time spent waiting for parts, people, approvals, and access. A lower MTTR means faster restoration.

How to Calculate MTTR

MTTR = Total Restoration Time / Number of Failures

Example: That same pump had 4 failures. The restoration times were 2 hours, 4 hours, 1.5 hours, and 2.5 hours.

Total Restoration Time = 2 + 4 + 1.5 + 2.5 = 10 hours
MTTR = 10 hours / 4 failures = 2.5 hours

The average restoration takes 2.5 hours.

What MTTR Tells You

High MTTR — Repairs take too long; investigate bottlenecks
Low MTTR — Your team responds and resolves quickly
Increasing MTTR — Parts availability, skill gaps, or equipment complexity may be issues
Decreasing MTTR — Procedures, training, or parts stocking improvements are working

Common MTTR Bottlenecks

When MTTR is too high, these are the usual culprits:

Diagnosis time — Technicians spend hours figuring out what’s wrong
Parts availability — Waiting for spare parts that aren’t in stock
Skill mismatch — Wrong technician assigned to the repair
Documentation gaps — No procedures or manuals available at the point of repair
Approval delays — Waiting for authorization to proceed with repairs

Using MTBF and MTTR Together

The real power comes from combining these metrics:

The pump from the examples: MTBF averages its running stretches, MTTR averages its repairs.

Equipment Availability

Availability = MTBF / (MTBF + MTTR) × 100%

Using our pump example:

Availability = 500 / (500 + 2.5) × 100% = 99.5%

Comparing Assets

When you track MTBF and MTTR across your asset fleet, patterns emerge:

Low MTBF + High MTTR — Your worst performers; prioritize these for PM or replacement
High MTBF + Low MTTR — Your best performers; study what’s working
Low MTBF + Low MTTR — Frequent but quick fixes; may indicate a recurring root cause
High MTBF + High MTTR — Rare but difficult failures; ensure parts and procedures are ready

Where an asset sits on MTBF and MTTR says what to do with it next.

How to Track MTBF and MTTR

Manual tracking with spreadsheets works but is error-prone and time-consuming. You need to record:

Every failure event with timestamp
Every repair completion with timestamp
Operating hours between failures

A CMMS automates this. When technicians complete breakdown work orders, the system calculates MTBF and MTTR.

Read MTBF and MTTR in FixAhead

The MTBF/MTTR report lists every asset with its figures for the period you pick.

1. Open MTBF/MTTR under Maintenance

On Reports & Analytics, choose the Maintenance tab, then MTBF/MTTR. The figures cover the period at the top right.

The MTBF/MTTR report: the Maintenance tab and its MTBF/MTTR sub-tab are open, the period reads Last 90 Days, and a table lists each asset with MTBF (Hours), MTTR (Hours), Failures and Reliability. — The MTBF/MTTR report for Last 90 Days, sorted by Breakdowns (Most first).

2. Read each asset’s row

Each row counts the breakdown work orders on an asset in the period. MTTR is the average hours from a breakdown work order’s creation to its completion. MTBF is the hours the asset was not under a breakdown work order, divided by its breakdowns; it counts calendar hours, not running hours, so it reads higher than the running-time MTBF above for an asset that does not run around the clock. Reliability is the share of the period the asset was not under a breakdown work order, the availability above. Only work orders marked as a breakdown count. Here the rows run from the most breakdowns down.

The MTBF/MTTR table, scrolled to its asset rows. Each row shows MTBF and MTTR in hours, Failures, and Reliability as a percentage in a green badge. — Asset rows in the MTBF/MTTR report, sorted by Breakdowns (Most first).

Review your baseline over the first year

There’s no universal “good” MTBF or MTTR — targets depend on your equipment, industry, and criticality levels. Start by baselining your current numbers, then review them on this schedule:

First 90 days — Establish baselines for your critical assets
6 months — Compare MTBF with the baseline, to see what PM has changed
12 months — Compare MTTR with the baseline, to see what procedures and parts stocking have changed

Calculate MTBF and MTTR for your own assets

Take the scheduled hours, unplanned downtime, and failures for one asset, and run them through the MTBF calculator. For MTTR, take its failures and the hours each took to get back in service, and run them through the MTTR calculator. Then repeat both for each critical asset, and track the results as they change.

How to Calculate MTBF and MTTR for Your Equipment

What is MTBF?