Reliability and uptime
OEE calculator
Overall Equipment Effectiveness is the share of planned production time that was genuinely productive. It multiplies three separate losses together, so a single low factor drags the whole figure down. That is the point of measuring it this way rather than averaging.
OEE = Availability × Performance × Quality
Run time as a share of planned production time
Actual output against the ideal cycle rate
Good units as a share of total units produced
Show the assumptions
- Formula
- OEE = Availability × Performance × Quality
The three factors are percentages, so the product is divided by 10,000 to return a percentage rather than a raw fraction.
Because the three factors multiply, OEE is always lower than its weakest input. Three respectable-looking 90% factors produce 72.9%. Track the factors separately as well as the product, or you will not know which loss to work on.
OEE
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Prefilled with an example. Change any number and the result updates.
How to calculate OEE
OEE = Availability × Performance × Quality
The three factors are percentages, so the product is divided by 10,000 to return a percentage rather than a raw fraction.
Worked example
- Availability 90 %
- Performance 95 %
- Quality 99.5 %
OEE = 85.1%
Reading the result
Because the three factors multiply, OEE is always lower than its weakest input. Three respectable-looking 90% factors produce 72.9%. Track the factors separately as well as the product, or you will not know which loss to work on.
Benchmarks
85% is the figure commonly cited as world class for discrete manufacturing, against a typical measured value closer to 60%. Treat both as orientation, not a target. OEE is only comparable against the same asset over time, because planned production time is defined locally.
OEE questions
What is a good OEE score?
85% is the widely cited world-class benchmark for discrete manufacturing, and 60% is closer to what most plants measure when they first calculate it honestly.
The more useful comparison is your own asset last quarter. OEE depends on how you define planned production time, and two plants that define it differently cannot be compared even if they run identical equipment.
Why is my OEE so much lower than each of the three factors?
Because they multiply rather than average. Availability 90%, performance 90% and quality 90% give an OEE of 72.9%, not 90%. Every percentage point of loss is applied to what survived the previous factor.
Does OEE include planned downtime?
No. OEE measures planned production time only, so scheduled maintenance, planned changeovers and shifts you never intended to run are excluded from the denominator. Including them gives you asset utilization, which is a different and usually much lower number.
Related calculators
Track OEE automatically
UpKeep records the work, the hours and the failures this metric depends on, so OEE is a report rather than a spreadsheet exercise.