Free tool
OEE calculator
Enter shift length, stops, ideal cycle time and part counts to get availability, performance, quality and OEE step by step, plus the minutes lost in each category.
Result
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OEE ·
Nakajima's 85% reference
How the OEE calculation works
OEE (Overall Equipment Effectiveness) shows how much of a machine's planned production time is spent making good parts. The calculator starts with the injection-moulding example from our OEE guide: a 480-minute shift, 30 minutes of planned breaks, 45 minutes of downtime losses, a 30-second ideal cycle, 750 parts and 30 defects. The result is 80.0%.
Percentages show overall effectiveness; turning losses into minutes shows which problem to tackle first. That is why the calculator also splits planned time into value-adding time, quality loss, speed loss and downtime loss.
Excel template
To record OEE shift by shift, download the production tracking and OEE form (Excel), which uses the same formulas. All tools and templates are on the tools page.
From manual to automatic OEE
Manual logs usually miss micro-stops and speed losses. When run, stop and count signals come straight from the PLC, the same calculation happens for every shift on its own. See our OEE software and MES and OEE implementation pages.
Frequently asked questions
Common questions
How is OEE calculated?
OEE = Availability × Performance × Quality. Availability is run time over planned production time, performance is ideal cycle time × total parts over run time, and quality is good parts over total parts. The calculator shows every step with your own numbers.
What is the difference between planned stops and downtime losses?
Planned stops (breaks, planned maintenance) are taken out of planned production time and do not affect OEE. Downtime losses (breakdowns, changeovers, set-up, waiting for material) stay inside planned time, come out of run time and lower availability. Changeovers may be on the schedule, but OEE usually counts them as an availability loss; write down for your plant which stops go where.
Why is performance above 100%?
If performance goes above 100%, the ideal cycle time you entered is longer than the machine's real fastest cycle. The ideal cycle time should be defined per product as the fastest cycle the machine can technically reach.
What is a good OEE?
The most quoted reference is 85%, based on Seiichi Nakajima's TPM work. It is a target marker; the most meaningful comparison is the same machine against its own history, calculated the same way.
Is my data stored anywhere?
No. The calculation runs entirely in your browser and nothing is sent to a server. "Copy link" only puts the values into the address bar so you can share the result.
Next step
Let’s turn your goal into a clear engineering scope.
Tell us about your plant, your machines and your goal. An integration engineer will set up a discovery call with you.
