OEE calculator: calculate OEE with a worked example
Enter one machine's numbers for a shift and the calculator works out availability, performance, quality and OEE as you type. Below it you will find what goes into each field, a worked example and how to read the result.
Last updated: 27 October 2026
OEE calculator
The fields start with an example. Type in the five numbers for one of your machines over the same shift and the result updates on the right.
OEE calculator
Enter the numbers from one of your own shifts, and the three factors and OEE are calculated as you type.
Run time 405 / 450 min
700 × 30 s / (405 × 60 s)
665 / 700
90.0% × 86.4% × 95.0%
The calculator runs in your browser. Nothing you type is sent anywhere or saved.
What to enter in each field
All five numbers have to come from the same machine and the same period. A shift, a day or a week all work, as long as the times and the counts cover the same stretch.
| Field | Unit | What goes in | Common mistake |
|---|---|---|---|
| Planned production time | minutes | The shift minus planned stops such as breaks, lunch and scheduled meetings. Hours when the machine is idle because nothing was scheduled stay out too. | Entering the whole shift. Breaks then show up as losses and availability drops for no reason. |
| Downtime | minutes | All unplanned stops within the planned time. Breakdowns, setups and changeovers, waiting for material, tool changes and no operator all count. | Leaving setups out, or adding the breaks here a second time. |
| Ideal cycle time | seconds per piece | The shortest time the machine can make a good part in. If one cycle makes several parts, divide by the number of parts. A 40-second cycle on a 4-cavity mold is 10 seconds a piece. | Using the average time or the time from the quote. Entering minutes instead of seconds is common too, 1.5 instead of 90. |
| Total pieces made | pieces | Every part that came off the machine in the period, scrap and rework included. | Entering only good parts. Quality then always comes out at 100%. |
| Good pieces | pieces | Parts that were good the first time. | Counting reworked parts as good. |
If the machine ran different parts in the shift, one ideal time is not enough. Multiply each part's count by its own ideal time, add those up and divide by the total count. Enter that weighted time as the ideal cycle time and performance comes out right.
The OEE formula the calculator uses
- Run time is planned production time minus downtime.
- Availability = Run time ÷ Planned production time
- Performance = (Total count × Ideal cycle time) ÷ Run time. Run time is multiplied by 60 so both are in seconds.
- Quality = Good count ÷ Total count
- OEE = Availability × Performance × Quality
What each ratio means, the six big losses and where OEE comes from are covered in the full guide, how to calculate OEE. This page is about filling in the calculator correctly.
OEE calculation example for a 10-hour shift on a machining center
A vertical machining center runs a 10-hour shift, which is 600 minutes, with 60 minutes of breaks. During the shift it spent 50 minutes on a setup, 25 minutes waiting for material and 15 minutes down after a broken tool. The ideal cycle time for the part is 90 seconds. By the end of the shift it made 255 parts, 8 of them scrap.
| Item | Calculation | Result |
|---|---|---|
| Planned production time | 600 − 60 | 540 min |
| Downtime | 50 + 25 + 15 | 90 min |
| Run time | 540 − 90 | 450 min |
| Availability | 450 ÷ 540 | 83.3% |
| Performance | 255 × 90 ÷ (450 × 60) | 85.0% |
| Good count | 255 − 8 | 247 pcs |
| Quality | 247 ÷ 255 | 96.9% |
| OEE | 0.833 × 0.850 × 0.969 | 68.6% |
Type 540, 90, 90, 255 and 247 into the calculator and you get the same result. The shortcut agrees too. 247 good parts × 90 seconds is 370.5 minutes, and 370.5 ÷ 540 is 68.6%. The biggest loss in this shift is availability. Setup accounts for 50 of the 90 minutes of downtime, so that is the first place to look.
How much does one wrong input change the result?
Here is the same shift calculated with three common mistakes. The difference is bigger than the mistakes look.
| Mistake | Entered | Result |
|---|---|---|
| Breaks counted as downtime | Planned time 600, downtime 150 | Availability 75.0%, OEE 61.7% |
| Average time used as ideal time | Ideal time 106 s (450 × 60 ÷ 255) | Performance 100.1%, OEE 80.8% |
| Ideal time entered in minutes | Ideal time 1.5 | Performance 1.4% |
The first mistake makes the machine look worse than it is and hides the real loss behind the breaks. The second does the opposite. The average time already contains every slowdown, so performance sticks at 100% and no loss shows. The calculator shows a warning when performance goes over 100%. If you see it, check the ideal cycle time first.
How to read your OEE score
The figure you hear most is 85%, often called "world class". Around 60% is usually described as typical and around 40% as low. These are rules of thumb that have been repeated for decades, not measured industry averages. A job shop that runs a different part every day with frequent setups cannot be judged by the same yardstick as a line making one part all year.
More useful than the single OEE number is which of the three factors is lowest.
- Low availability means the machine is stopped. Sort stops by reason and start with the one that adds up to the most time. The machine downtime tracking guide covers how.
- Low performance means the machine runs but slowly. Short stops nobody writes down, cautious feed rates and a wrong ideal time are the usual suspects.
- Low quality means looking at where scrap happens. Is it in the first parts after a setup, or during normal running?
The comparison that matters is the same machine this week against last week. Put a few weeks side by side and you can tell whether a change you made actually helped.
Getting the numbers without collecting them by hand
The calculator is fine for one shift. Collecting stops and counts from paper for every machine every day is a job that usually gets dropped within weeks. ModernMES records these inputs on the shop floor while the work is done. Operators pick a reason when they pause a job on the terminal or their phone, and the stop is logged under that reason. Each reason is marked up front as counting toward OEE or not, so a break does not count and a breakdown does. Good and scrap counts are entered when a job is finished. You can see what it looks like in the live shop floor demo.
Frequently asked questions
How do you calculate OEE?
OEE is availability × performance × quality. Availability is run time divided by planned time, performance is total count × ideal cycle time divided by run time, and quality is good count divided by total count. As a shortcut, good count × ideal cycle time divided by planned production time gives the same answer.
Should breaks go into the downtime field?
No. Breaks, lunch and scheduled meetings come off planned production time first. Downtime is only for unplanned stops within the planned time, such as breakdowns, setups and waiting for material.
What ideal cycle time do I enter if the machine ran different parts?
Multiply each part's count by its own ideal time, add the results and divide by the total count. With that weighted time, performance comes out the same as if you had calculated each part separately.
What period should I calculate OEE for?
A shift or a day is enough to start. When you compare, always use periods of the same length. For a weekly figure, take planned time, downtime and counts as totals for the week rather than averaging the daily percentages.
Is anything I type into the calculator saved?
No. The calculation happens entirely in your browser. The numbers are not sent to a server and are gone when you close the page.
Related pages
- How to Calculate OEE: Formula, Example, CalculatorThe OEE formula (availability × performance × quality), a step-by-step worked example on a CNC lathe, the six big losses, common mistakes and a free calculator.
- Machine Downtime Tracking: Downtime Reasons and AnalysisHow to track machine downtime: a short list of downtime reasons, paper vs Excel vs software, Pareto analysis, MTTR and MTBF, and common mistakes.
- What Is MES? Manufacturing Execution System Software ExplainedWhat a manufacturing execution system (MES) does in production, how it differs from ERP and MRP, the MES software options and what to look for when choosing one.
- Production Tracking Software for Small ManufacturersProduction tracking software for job shops: see which job is on which machine, who runs it, good and scrap counts and why it stopped. Free for 14 days.