Maintenance KPIs: The Complete Guide (List, Examples, and Comparison Table)
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- In maintenance, what doesn't get measured cannot be improved.
Maintenance KPIs are the reference points that help teams steer interventions, anticipate breakdowns, and control costs on a daily, weekly, or even monthly basis. This guide walks through the most important maintenance key performance indicators, how to calculate them, and how to use them to build a data-driven maintenance program that actually moves the needle.
What Are Maintenance KPIs?
Maintenance KPIs (key performance indicators) are quantitative metrics that measure the performance of equipment and maintenance processes over time. They turn breakdowns, downtime, and costs into objective data that can be analyzed, benchmarked, and improved.
Used well and managed continuously, maintenance key performance indicators help teams:
- Reduce unplanned downtime and improve equipment availability.
- Control and optimize maintenance costs relative to production or revenue.
- Strengthen safety by limiting critical and recurring failures.
- Prioritize investments between asset renewal and preventive maintenance.
- Build a shared language between technicians, planners, and executives.
Good to know: The European standard EN 15341 defines a full framework of maintenance KPIs, split into technical, organizational, and economic indicators. It’s a useful reference when you’re building your own KPI dashboard.
Categories of Maintenance KPIs
Reference frameworks and the EN 15341 standard organize maintenance KPI metrics into several complementary categories:
- Technical indicators: reliability and availability of equipment (MTBF, MTTR, MTTF, MTTD, availability, failure rate).
- Operational indicators: how maintenance is organized — schedule compliance, backlog, planned vs. corrective work.
- Production and performance indicators: OEE, downtime, unplanned failures.
- Economic indicators: maintenance cost, cost per asset, cost per unit produced, cost per hour of downtime.
- Quality and service indicators: rework rate, non-conformities, SLA compliance.
Most companies operate with a core of 8 to 12 maintenance KPIs, supplemented by more detailed metrics for ad-hoc analysis. Piling on dozens of indicators usually dilutes attention rather than sharpening decisions.
Technical Maintenance KPIs: MTBF, MTTR, MTTF, MTTD, Availability and Failure Rate
Technical maintenance KPIs are the foundation of any maintenance tracking program. They describe how reliable your assets are, how quickly your team responds, and how much productive time you actually get out of your equipment.
MTBF: Mean Time Between Failures
MTBF (Mean Time Between Failures) measures the average operating time between two failures for a repairable piece of equipment or a family of assets.
Formula:
MTBF = Total operating time ÷ Number of failures
Example: A machine runs for 1,000 hours over a period and experiences 5 failures. MTBF = 1,000 ÷ 5 = 200 hours.
This maintenance KPI is used to:
- Compare reliability across assets.
- Track the effect of a preventive maintenance plan.
- Prioritize replacements and modernizations.
MTTR: Mean Time To Repair
MTTR (Mean Time To Repair) measures the average time needed to fix an asset and bring it back into service.
Formula:
MTTR = Total repair time ÷ Number of repairs
Example: Over a period, an asset experiences 4 failures with 10 total repair hours. MTTR = 10 ÷ 4 = 2.5 hours.
A low MTTR reflects:
- The responsiveness of maintenance teams.
- The quality of diagnostics and troubleshooting.
- The availability of spare parts and tooling.
MTTF: Mean Time To Failure
MTTF (Mean Time To Failure) measures the average time before failure for non-repairable equipment or components (sensors, modules, certain consumables) that are replaced rather than repaired.
Formula:
MTTF = Total operating time of the assets ÷ Number of failures
This maintenance KPI is especially useful to:
- Plan replacements before failure disrupts operations.
- Size spare parts inventory correctly.
- Optimize budgets on critical components.
MTTD: Mean Time To Detect
MTTD (Mean Time To Detect) measures the average time between when an incident occurs and when it is actually detected.
In an IT or IoT environment, MTTD tells you how long it takes for a failure to surface in your CMMS or supervision tool. A low MTTD means good visibility; a high MTTD signals incidents that stay latent for too long, quietly eroding availability and safety.
Availability and Failure Rate
Availability measures the percentage of time an asset is ready to produce or deliver service.
A common formula combines MTBF and MTTR:
Availability = MTBF ÷ (MTBF + MTTR)
The failure rate (number of failures ÷ operating time, or failures per asset) complements these KPIs by tracking how defects evolve over time. Reading availability and failure rate together makes it easier to tell whether reliability is truly improving or whether faster repairs are simply masking a growing failure problem.
Operational Maintenance KPIs: Planned Maintenance, Backlog, and Schedule Compliance
Beyond downtime, operational maintenance KPIs reveal how the maintenance function is organized, how well it plans, executes, and stays ahead of the workload.
Planned Maintenance Percentage (PMP)
The planned maintenance percentage (PMP) measures the share of preventive and planned interventions relative to total work orders.
Formula:
PMP = Planned work orders ÷ Total work orders × 100
Industry references typically cite a target above 80–90% for mature organizations, with unplanned corrective work kept to a minimum. A PMP below 50% usually signals a reactive, firefighting culture that will keep burning technician hours and cash.
Maintenance Backlog
The maintenance backlog represents the volume of maintenance work waiting to be executed, generally expressed in weeks of available capacity.
Formula:
Backlog = Planned work order hours ÷ Weekly available capacity
A backlog that’s too low may indicate weak planning or over-staffing. Too high, and it signals chronic overload and rising risk on the equipment. Many teams target a healthy range of 2 to 4 weeks of ready backlog.
Schedule Compliance
Schedule compliance measures the share of interventions completed on time as originally planned.
Formula:
Schedule compliance = Work orders completed on time ÷ Work orders planned × 100
The commonly cited target is around 80–85%. Below that, planners spend most of their time re-shuffling the schedule instead of improving it which is a classic symptom of firefighting mode.
Production KPIs: OEE and Downtime
Maintenance is never a goal in itself: it serves production and service delivery. That’s why production-oriented maintenance KPIs are essential to connect the maintenance team’s work to business outcomes.
Overall Equipment Effectiveness (OEE)
OEE (Overall Equipment Effectiveness) is the reference indicator for measuring how effectively equipment is used. It combines three factors into a single score.
Formula:
OEE = Availability × Performance × Quality
Reference guides cite an OEE above 85% as world-class performance, though realistic targets depend heavily on the industry and the process. In many discrete manufacturing environments, OEE sits between 40% and 60%, with plenty of room for improvement.
Total Downtime and Unplanned Failures
Total downtime covers all periods when the equipment is not producing: breakdowns, setups, changeovers, and planned maintenance.
Within that, unplanned failures are the metric that really tells you whether preventive maintenance is working. A drop in unplanned downtime, not just total downtime, is what proves your program is acting upstream instead of reacting to problems.
Mean Downtime per Failure
Mean downtime per failure looks at the average impact of each stoppage on production. It’s close to MTTR, but includes the full time the asset is not producing (waiting time, diagnostics, parts, repair, and restart), not just the wrench time. This is often the KPI operations leaders care about most, since it maps directly to lost output.
Economic Maintenance KPIs: Cost and Budget
For executives, maintenance KPIs also have to speak the language of money. Economic maintenance KPI examples turn technical performance into financial impact.
- Maintenance Cost as a Percentage of Revenue
The maintenance cost to revenue ratio measures how much of your revenue is spent on maintenance.
Formula:
Maintenance cost ÷ Revenue × 100
A commonly cited benchmark for a healthy maintenance-to-revenue ratio is around 5%, though this varies significantly by industry — asset-heavy sectors like mining or heavy manufacturing usually run higher.
- Cost per Work Order and Cost per Asset
The average cost per work order and the maintenance cost per asset track the financial impact of technical decisions (type of intervention, outsourcing, modernization).
Example formula:
Average cost per work order = Total intervention cost ÷ Number of work orders
These maintenance KPI metrics make it easier to compare sites, teams, or external service providers — and to spot the assets that are quietly eating your budget.
- Cost per Hour of Downtime
Cost per hour of downtime puts a dollar value on every hour an asset isn’t running. It includes lost production, idle labor, and (when relevant) penalties or service credits. It’s the most persuasive KPI when you need to justify preventive maintenance investment or a CMMS project to finance leaders.
Comparison Table of the Main Maintenance KPIs
Here’s a comparison table summarizing the main maintenance KPIs, with their calculation logic and primary use case.
| Category | KPI | Definition | Calculation | Primary Use |
|---|---|---|---|---|
| Technical | MTBF | Mean time between failures | Operating time ÷ Number of failures | Measure reliability of repairable assets |
| Technical | MTTR | Mean time to repair | Total repair time ÷ Number of repairs | Track team responsiveness and repair efficiency |
| Technical | MTTF | Mean time to failure | Total operating time ÷ Number of failures | Plan replacement of non-repairable assets |
| Technical | MTTD | Mean time to detect | Time between occurrence and detection ÷ Incidents | Evaluate supervision and monitoring systems |
| Technical | Availability | % of operational time | MTBF ÷ (MTBF + MTTR) | Steer production and service capacity |
| Operational | PMP | Planned maintenance percentage | Planned ÷ Total work orders × 100 | Measure preventive vs. corrective balance |
| Operational | Backlog | Maintenance work waiting | Planned hours ÷ Weekly capacity | Track workload and priorities |
| Operational | Schedule compliance | On-time completion rate | On-time work orders ÷ Planned × 100 | Assess planning discipline |
| Production | OEE | Overall equipment effectiveness | Availability × Performance × Quality | Link maintenance to production output |
| Production | Downtime | Total immobilization time | Sum of downtime over the period | Quantify impact of stoppages |
| Economic | Cost ÷ Revenue | Maintenance share of revenue | Total maintenance cost ÷ Revenue × 100 | Provide top-level cost view |
| Economic | Cost per work order | Average cost of an intervention | Total intervention cost ÷ Work orders | Benchmark sites, teams, providers |
| Economic | Cost per hour of downtime | Financial impact of stoppages | Lost revenue + labor + penalties per hour | Justify preventive investment |
How to Use Maintenance KPIs Effectively With a CMMS
The real value of maintenance KPIs shows up when they’re tracked continuously and fed by clean, structured data, not spreadsheets rebuilt every quarter. That’s where CMMS KPIs come into play: a modern CMMS (Computerized Maintenance Management System) automatically captures work orders, downtime, parts usage, and costs, then turns them into dashboards.
To get real value out of your maintenance KPI metrics:
- Start small: pick 5 to 8 KPIs that map directly to your business priorities.
- Assign an owner to each KPI, a metric without an owner is a metric no one improves.
- Automate data capture through your CMMS to avoid manual entry drift.
- Review KPIs on a fixed cadence (weekly for operational, monthly for economic).
- Combine leading and lagging indicators, schedule compliance and PMP predict tomorrow’s MTBF and downtime.
With Timly, teams can centralize asset data, track interventions, and monitor maintenance KPIs like MTBF, MTTR, planned maintenance percentage, and cost per work order in real time. Because Timly links each intervention to a specific asset and its history, calculating maintenance KPI metrics stops being a manual reporting exercise and becomes a live view of how your operations are performing.
“Maintenance KPIs are only as valuable as the decisions they enable. When teams can connect every intervention, failure, downtime event, and cost directly to the asset involved, they move from reacting to problems to understanding and improving their entire maintenance operation.“
Mehmeti
Timly Software AG
Building a Sustainable Maintenance Performance Culture
MTBF, MTTR, MTTF, MTTD, OEE: these maintenance KPIs form the foundation of effective equipment and intervention management.
Combined across categories (e.g., technical, operational, economic, and production) they offer a complete picture of maintenance performance.
The point isn’t how many KPIs you track, but their quality: reliable indicators, updated regularly, and, above all, usable by the teams on the ground. A KPI that lives only in a monthly executive report will never change behavior on the shop floor.
Used well, these maintenance key performance indicators do more than cut breakdowns and costs. Over time, they build a genuine culture of continuous improvement where every intervention is a data point, and every data point becomes a decision. Maintenance management software like Timly make that shift practical by turning day-to-day maintenance activity into structured, shareable KPI data.
FAQs About Maintenance KPIs
A maintenance KPI is a quantitative metric used to evaluate the performance of a maintenance activity, asset, or service (e.g., covering reliability, availability, cost, and organization) based on measurable data such as downtime, failures, work orders, and expenses.
The main maintenance key performance indicators include:
- MTBF (mean time between failures)
- MTTR (mean time to repair)
- MTTF (mean time to failure, for non-repairable assets)
- MTTD (mean time to detect incidents)
- Equipment availability
- Total downtime
- OEE (overall equipment effectiveness)
- PMP (planned maintenance percentage)
- Maintenance backlog
- Schedule compliance
- Maintenance cost to revenue ratio
- Average cost per work order
- Maintenance cost per asset
- Cost per hour of downtime
- MTBF measures the average time between failures on repairable assets.
- MTTR measures the average time needed to repair an asset.
- MTTF measures the average time before failure for non-repairable assets.
- MTTD measures the average time between an incident occurring and being detected.
An OEE above 85% is generally considered world-class. In practice, many discrete manufacturing operations run between 40% and 60%, and continuous improvement of maintenance KPIs like MTBF, MTTR, and PMP is what gradually lifts that number.
The European standard EN 15341 defines and lists key maintenance performance indicators, providing guidelines for how to define and use them. It's the reference framework in Europe for structuring maintenance KPI programs.
