OEE Calculator
Overall Equipment Effectiveness from its three factors: availability, performance and quality, each entered as a percentage.
Formula
OEE = Availability × Performance × Quality
With each factor as a percentage, divide by 100 before multiplying and convert the product back to a percentage — which is what the calculator above shows step by step.
What the three factors describe
- Availability — time lost to stoppages within planned production time.
- Performance — output lost to running slower than the ideal cycle rate, including minor stops.
- Quality — output produced that did not meet specification first time.
Assumptions & boundaries
- All three factors must cover the same equipment and the same period.
- The performance factor depends on an agreed ideal cycle time; an optimistic ideal rate suppresses OEE artificially.
- What counts as planned production time is a local definition and strongly affects the availability factor.
- OEE for a single machine does not describe the throughput of the whole line unless that machine is the constraint.
Worked example
A packaging line reports availability 90%, performance 95% and quality 99%.
OEE = 0.90 × 0.95 × 0.99 × 100 = 84.65%
Each factor looks strong alone, yet roughly 15% of planned production time did not convert into good output — the compounding effect that makes OEE useful as a summary figure.
Frequently asked questions
- Is OEE a reliability metric?
- No. OEE is a manufacturing effectiveness metric. It combines time losses, speed losses and quality losses into one figure. Reliability describes the ability to perform without failure over time, which OEE does not isolate.
- Why is my OEE lower than each individual factor?
- Because the three factors multiply. Three factors of 90% give 0.90 × 0.90 × 0.90 = 72.9%. Multiplication means a small loss in each dimension compounds into a much larger total loss.
- Which availability goes into OEE?
- The OEE availability factor is based on planned production time, so planned downtime is normally excluded from the denominator. That makes it different from an asset availability KPI measured over calendar time. Do not assume the two numbers are interchangeable.
- Can OEE be compared between plants?
- Only with care. OEE depends on how planned production time, ideal cycle time and quality rejects are defined locally. Comparing the trend of one line against itself is usually more informative than comparing sites.