Free OEE Calculator
Find out how effective your machine really is, and which loss is costing you the most.
This calculator needs JavaScript. You can still read how the numbers are worked out below, including a worked example.
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How this OEE calculator works
OEE (overall equipment effectiveness) is the share of planned production time that produced good parts at full speed. The calculator multiplies three factors:
OEE = Availability × Performance × Quality
- Availability = run time ÷ planned production time
- Performance = (ideal cycle time × total count) ÷ run time
- Quality = good count ÷ total count
Planned production time is the shift length minus planned stops. Run time is planned production time minus downtime.
Worked example
A CNC machine runs an 8-hour shift (480 minutes) with 60 minutes of planned stops, so planned production time is 420 minutes. It is down for 45 minutes, so run time is 375 minutes. The ideal cycle time is 90 seconds, and it makes 220 parts, 209 of them good.
| Factor | Calculation | Result |
|---|---|---|
| Availability | 375 ÷ 420 | 89.3% |
| Performance | (1.5 min × 220) ÷ 375 | 88.0% |
| Quality | 209 ÷ 220 | 95.0% |
| OEE | 89.3% × 88.0% × 95.0% | 74.6% |
What is a good OEE score?
| OEE | What it usually means |
|---|---|
| 85% or more | World class for discrete manufacturing |
| 60–85% | Good, with clear room to improve |
| 40–60% | A typical starting point when plants first measure OEE |
| Below 40% | Low; large, fast gains are likely |
Compare OEE over time on the same machine, not across different machines or industries.
Getting accurate numbers
- Use the machine's design speed for ideal cycle time. A padded "standard" time hides speed losses.
- Count only parts that are right first time as good.
- Treat changeovers as downtime. They are a loss you can reduce.
- Calculate OEE per machine or line, not as a plant-wide average.
From one shift to every machine
This calculator works for one machine and one shift. To see OEE losses across a whole plant, every breakdown needs to be recorded with its cause, every PM tracked and every repair timed. That is what a CMMS like PlantOps360 does: breakdowns raised by QR scan with failure codes, preventive maintenance by time, usage or meter reading, and dashboards for MTTR, MTBF and failure trends.