Running maintenance without maintenance KPIs is like driving with your eyes closed. Metrics like MTBF and MTTR turn a pile of work orders into usable information: which equipment causes trouble, where the time goes, how much upkeep really costs. But you still need to pick the right indicators, know how to calculate them, and track them over time.
This guide covers the maintenance KPIs that genuinely matter, with clear definitions, how to calculate them, and how a CMMS automates their tracking.
MTBF: mean time between failures
MTBF (Mean Time Between Failures) measures an asset’s reliability. It indicates the average time a machine runs between two failures.
Calculation: MTBF = total operating time / number of failures over the period.
Example: a machine runs 800 hours and fails 4 times. Its MTBF is 200 hours. The higher the MTBF, the more reliable the equipment. It’s the flagship metric for spotting machines that break too often and prioritizing your preventive efforts.
MTTR: mean time to repair
MTTR (Mean Time To Repair) measures your responsiveness and the efficiency of your interventions. It’s the average time needed to restore an asset after a failure.
Calculation: MTTR = total repair time / number of interventions.
Example: 4 repairs took 8 hours in total. The MTTR is 2 hours. A high MTTR points to concrete problems: unavailable parts, difficult diagnosis, unclear procedures, lack of skills. Reducing MTTR often means acting on parts stock and on the quality of your procedures.
MTBF and MTTR are read together: the first tells you how often things break, the second how long it takes to repair them.
Availability rate: the visible result
The availability rate (or operational availability) expresses the share of time an asset is actually fit to produce. It’s the metric that speaks most to production and management.
Calculation: Availability = MTBF / (MTBF + MTTR).
With an MTBF of 200 hours and an MTTR of 2 hours, availability is 200 / 202, or about 99%. This KPI combines reliability (MTBF) and speed of restoration (MTTR): improving either one moves it up. It’s an excellent summary indicator to display on a dashboard.
Preventive ratio: the balance of your strategy
The preventive maintenance ratio measures the share of your interventions that are planned, as opposed to reactive repairs.
Calculation: Preventive ratio = preventive interventions / total interventions.
A low ratio signals reactive maintenance, where the team spends its time firefighting. Conversely, a very high ratio can betray over-maintenance. This indicator isn’t about chasing perfection: it helps you check that you’re gradually shifting from corrective to preventive work on your critical equipment. To dig deeper into this trade-off, see our guide on preventive versus corrective maintenance.
Maintenance cost per asset
The cost per asset aggregates all spending tied to a machine: labor, parts consumed, external services. It’s the metric that informs investment decisions.
Calculation: Cost per asset = sum of costs (labor + parts + subcontracting) over the period, per machine.
Tracked over time, it reveals equipment that costs more to maintain than to replace. It justifies a renewal, arbitrates between in-house work and outsourcing, and makes conversations with finance objective. Without a reliable history, this calculation is impossible; that’s precisely what a CMMS records at every intervention.
How to track these KPIs in a CMMS
Calculating these indicators by hand in a spreadsheet is tedious and quickly abandoned: you have to re-enter every failure, every duration, every cost. A CMMS captures this data at the source, the moment a technician closes their work order, then computes the indicators automatically.
A few good practices for reliable KPIs:
- Capture at the source: each intervention is recorded with its duration, parts, and reason. KPI quality depends on data-entry quality.
- Standardize reasons: clearly distinguish failure, preventive, and improvement work so the ratios make sense.
- Track trends, not isolated values: an MTBF at a single point in time says nothing; its curve over six months tells a story.
- Show KPIs to the team: a shared dashboard motivates and makes priorities objective.
With Maint Vision, these calculations are automatic. The reporting and analytics module aggregates MTBF, MTTR, availability, preventive ratio, and cost per asset into clear dashboards, updated in real time as your technicians close their work orders from the mobile app.
In short
The right maintenance KPIs are few but decisive: MTBF for reliability, MTTR for responsiveness, availability rate for the visible result, preventive ratio for the balance of your strategy, and cost per asset for investment decisions. Together, they turn your maintenance into a fact-driven practice.
The hard part isn’t knowing the formulas but having reliable data to feed them. That’s the job of a CMMS: capture every intervention and derive the indicators without re-entry.
Try Maint Vision for free, no credit card and track your maintenance KPIs in real time. Data hosted in Europe (Frankfurt).