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OEE calculator
Enter one shift and get overall equipment effectiveness with availability, performance and quality shown separately. The calculator also splits the shift into minutes, so you can see exactly where the lost time went, and tells you which factor to fix first.
The OEE formula
OEE = Availability × Performance × Quality
| Factor | Formula | Example shift | Loss it measures |
|---|---|---|---|
| Availability | Run time / planned production time | 405 / 450 = 90.0% | Stops: breakdowns, changeovers, waiting |
| Performance | (Ideal cycle time × total count) / run time | (60 × 350) / (405 × 60) = 86.4% | Running slower than the ideal |
| Quality | Good count / total count | 336 / 350 = 96.0% | Scrap and rework |
| OEE | The three multiplied | 90.0 × 86.4 × 96.0 = 74.7% | All of it together |
Multiply the three out and they reduce to a shorter form: OEE = (good count × ideal cycle time) / planned production time. In the example, 336 good units at 60 seconds is 336 fully productive minutes out of 450 planned, which is 74.7 percent again. The short form is a useful check, but it cannot tell you which loss to go after, and that is the point of measuring OEE. The definitions here follow Vorne's OEE reference.
Read OEE as minutes, not percentages
A percentage tells you the line is at 74.7. Minutes tell you what to do about it. The same 450 minute shift, split by cause:
| Where the time went | Minutes | How it is worked out |
|---|---|---|
| Stopped | 45 | Stop time as entered |
| Running slow | 55 | Run time 405, less 350 units at the 60 second ideal (350 minutes) |
| Making bad parts | 14 | 14 rejected units at 60 seconds each |
| Fully productive | 336 | 336 good units at 60 seconds, which is 74.7% of 450 |
The biggest loss here is not the downtime. Everyone saw the 45 minutes the line was stopped. Nobody saw the 55 minutes it spent running slower than it can, because the line was running the whole time. Performance loss is where small stops and slow cycles hide, and it is usually the one worth timing properly.
What is a good OEE score?
The number usually quoted as world class OEE is 85 percent. It goes back to Seiichi Nakajima, who introduced OEE alongside Total Productive Maintenance, and it is built from separate goals for each factor. The same source that popularised it notes most manufacturers run closer to 60 percent.
| Factor | World class goal | Example shift | OEE if only this factor hit its goal |
|---|---|---|---|
| Availability | 90% | 90.0% | Already there, no change |
| Performance | 95% | 86.4% | 82.1% |
| Quality | 99.9% | 96.0% | 77.7% |
| OEE | 85% | 74.7% |
That last column is the useful one. Lifting quality to its goal moves OEE to 77.7 percent. Lifting performance moves it to 82.1 percent, so performance is where this line should start. The calculator above runs the same comparison on your own figures. Two cautions: these goals are for discrete manufacturing, and all three factors at 90 percent only gives 73 percent, so a respectable looking set of factors can still produce an unimpressive OEE.
The six big losses behind each factor
Each factor collects two kinds of loss. Naming them is what turns an OEE score into a list of things to fix. This grouping follows the six big losses as Vorne describes them.
| Factor | Loss | What it looks like on the floor |
|---|---|---|
| Availability | Equipment failure | The machine is down for a breakdown. |
| Availability | Setup and adjustments | Changeovers, tooling swaps, warm up. |
| Performance | Idling and minor stops | Stops of a minute or two the operator clears, jams, misfeeds. |
| Performance | Reduced speed | Running slower than the ideal cycle time. |
| Quality | Process defects | Scrap and rework once production is stable. |
| Quality | Reduced yield | Scrap and rework during start up. |
Where OEE calculations go wrong
Using the average cycle time as ideal
Performance compares you against the fastest the process can run. Enter your average and performance will sit near 100 percent while the slow running stays invisible.
Performance over 100 percent
That is not a great day. It means the ideal cycle time entered is slower than the line really runs. Reset it to the rated or best sustained speed.
Counting reworked parts as good
OEE quality is first pass yield. A part that went back for rework counts as bad even if it shipped.
Leaving changeovers out of stop time
A changeover is time the line was meant to run and did not. Take it out of planned time and availability looks better than it is.
Averaging the shift percentages
A short shift should not weigh as much as a full one. Add up the minutes and counts across shifts, then work out OEE once.
Comparing OEE across different lines
A line changed over five times a day and a line that runs one product all week will never score alike. Track each line against its own history.
Performance and cycle time are two views of the same thing: performance is ideal cycle time divided by actual cycle time. The example line runs at 69.4 seconds a unit against a 60 second ideal, which is where its 86.4 percent comes from. The cycle time calculator works out that actual figure from a shift, and times a stopwatch study if you need one.
Where the quality number comes from
OEE needs a good count, and a good count needs somebody recording what failed inspection and what happened to it. That record lives in production software, so it is worth being precise about what each side does.
What Fabrica ERP does
- Completed work orders wait in Pending Inspections for a final quality check before they ship.
- A failed check is logged as a nonconformance report with a disposition of Rework, Scrap or Accept as Is, and open reports show up on the dashboard.
- The quality control screen shows a scrap rate and a rework rate across the reports you have logged.
What it does not do
- It does not calculate OEE. It does not time operations or record downtime either, so availability and performance still come from your own logs, this page and the workbook.
- Its scrap and rework rates are shares of the reports you logged, not of units made, so they are not the OEE quality factor.
- Logging a scrap disposition does not adjust inventory. Stock has to be corrected by hand afterwards.
See the quality and shop floor side for yourself
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Start the 14 day free trialTalk to us about a custom buildCommon questions
How do you calculate OEE?
OEE = availability x performance x quality. Availability is run time divided by planned production time. Performance is ideal cycle time times total count, divided by run time. Quality is good count divided by total count. For a 450 minute planned shift with 45 minutes stopped, a 60 second ideal cycle, 350 units made and 336 good, that is 90.0 x 86.4 x 96.0 percent, which comes to 74.7 percent.
What is the formula of OEE?
The full formula is availability x performance x quality. It reduces to a shorter one: OEE = (good count x ideal cycle time) / planned production time. In the example that is 336 x 60 / (450 x 60) = 74.7 percent. The short form gives the same answer but hides which of the three losses is the big one, so work out the factors as well.
What is a good OEE score?
85 percent is the figure usually called world class. It traces back to Seiichi Nakajima, who introduced OEE with Total Productive Maintenance, and it breaks down as roughly 90 percent availability, 95 percent performance and 99.9 percent quality. Most manufacturers run closer to 60 percent. A score that keeps improving matters more than any fixed target, and a line changed over several times a day will score lower for reasons that have nothing to do with how well it is run.
What does 85% OEE mean?
It means 85 percent of the time you planned to produce was fully productive: making only good parts, at the ideal speed, with no stops. The other 15 percent was lost to stops, slow running or bad parts. It does not mean the line was running 85 percent of the time.
What does 100% OEE mean?
Only good parts, made as fast as the process can make them, with no stop time at all during the planned production time. It is a reference point rather than a target. If your calculation shows performance above 100 percent, the ideal cycle time you entered is slower than the line really runs, so fix that input rather than celebrating.
How do I calculate OEE in Excel?
With planned production time in minutes in B2, stop time in C2, ideal cycle time in seconds in D2, total count in E2 and good count in F2, use =(B2-C2)/B2 for availability, =D2*E2/((B2-C2)*60) for performance, =F2/E2 for quality, and multiply the three for OEE. =F2*D2/(B2*60) gives OEE in one cell. The workbook further down has these written in as live formulas.
What is the difference between OEE and TEEP?
OEE measures how well you use the time you planned to produce. TEEP, total effective equipment performance, measures against every hour in the week: TEEP = OEE x utilization, where utilization is planned production time divided by all time. A line with 74.7 percent OEE that runs one 37.5 hour shift pattern a week has a TEEP of about 16.7 percent, which shows how much capacity is sitting unused.
Should changeovers count against availability?
Yes. Stop time is any time the process was meant to be running and was not, and that includes planned stops such as changeovers as well as breakdowns. What comes out before you start is time you never planned to produce in, such as breaks, lunch and shifts you do not run.
Do reworked parts count as good in OEE?
No. Quality in OEE is first pass yield, so a part that needed rework counts as bad even if it ships in the end. Counting reworked parts as good is one of the most common ways an OEE score ends up higher than the line deserves.
What are the six big losses?
Equipment failure and setup and adjustments reduce availability. Idling and minor stops and reduced speed reduce performance. Process defects and reduced yield, the bad parts made during start up, reduce quality. The breakdown in the calculator maps your minutes onto those three groups.
Related
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Seconds per unit, units per hour and the pace your downtime really costs.
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Fabrica ERP: work orders, shop floor, quality control and QuickBooks sync.
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Custom maintenance and work order systems, for the breakdown side of availability.