MTTR (Mean Time to Repair)

MTTR (mean time to repair) is a maintenance metric that measures the average time it takes to repair a piece of equipment or resolve an incident, from the moment the failure is detected until the asset is operational again. It is calculated by dividing the total accumulated repair time by the number of repairs in a period.

It is one of the core KPIs of maintenance and field service: the lower the MTTR, the less time an asset (a machine, a vehicle, equipment installed at a customer site) stays down. In technical service operations, it is part of what is managed in Field Service, where the goal is to shorten the cycle between the failure report and an effective fix.

Unlike metrics that look at how often failures happen, MTTR focuses on speed of response and repair: it answers the question of how long it takes us to fix something when it breaks.

MTTR sums up in a single number how quickly a maintenance or technical service team can react. The basic formula is simple: add up the total time spent on repairs during a period and divide it by the number of repairs performed. If 10 repairs in a month added up to 40 hours of actual work, the MTTR is 4 hours per repair.

What looks like a trivial calculation hides an important decision: what counts as "repair time." Some organizations measure only hands-on time, that is, the technician working on the equipment. Others measure the full time from when the failure is reported, which includes diagnosis, the technician's travel, waiting for parts and the repair itself. The second version is more honest about the customer experience, because for whoever has the machine down it makes no difference whether the technician was delayed by travel or by a missing part: the asset is still not working.

Why MTTR matters

Every hour an asset is out of service costs money. In a consumer goods plant, a stopped packaging line holds up all downstream production. In field service, equipment that fails at a customer's facility hurts satisfaction and can trigger penalties under the SLA. Reducing MTTR is, in practice, reducing the cost of downtime and protecting the customer relationship.

A low MTTR does not come from fast technicians alone. It usually depends on several factors combined:

• Fast diagnosis: with telemetry or the asset's history at hand before arriving.
• Parts available: so the repair does not stall waiting for a component.
• Smart dispatch: assigning the technician with the right skill and the shortest distance.
• Documented work order: so the technician does not improvise on equipment they do not know.
• First-visit resolution: measured with the first-time fix rate, which prevents reopened jobs.

MTTR vs MTBF: two sides of the same asset

MTTR is almost never looked at alone. Its natural counterpart is MTBF (mean time between failures), which measures how often the equipment breaks down. While MTBF speaks to reliability (how often it fails), MTTR speaks to maintainability (how quickly it recovers). Together they determine the asset's overall availability: equipment that rarely fails but takes days to repair can have worse availability than equipment that fails more often but is fixed in an hour.

A concrete example

An Argentine foodservice equipment company installs and maintains industrial ovens for restaurant chains. Before, when an oven failed, the cycle was slow: the customer called, someone wrote down the complaint, and only the next day was a technician dispatched, who often arrived without the right part and had to come back. MTTR hovered around 36 hours and the customer lost service for days. After organizing the flow (digital logging of the complaint, accessible equipment history, dispatch of the nearest technician carrying common spare parts), MTTR dropped to under 8 hours and reopened jobs fell. What changed was not just a dashboard metric: it was real hours of ovens back in production.

Common mistakes when measuring MTTR

• Averaging without segmenting: mixing major and minor repairs hides the fact that critical failures take a very long time.
• Counting only hands-on time: you report an excellent MTTR while the customer waited three days for a part.
• Not recording detection: without the exact moment the failure appeared, the calculation is unreliable.
• Using it to punish: pressuring technicians with MTTR encourages rushed, poorly documented repairs.

Measured well and segmented by asset type and criticality, MTTR stops being a reporting number and becomes a management lever: it shows where the maintenance operation gets stuck and what needs fixing first.