OEE Calculator
See how much of your planned production time went on making good parts at full speed, and where the rest was lost: stops, slow running or rejects.
Meetings, planned maintenance or no orders. Changeovers count as downtime, below.
The rest of the speed loss counts as slow cycles, and the rest of the rejects as production rejects.
Where your planned time went
Each loss is shown as time. Orange: availability loss, yellow: performance loss, purple: quality loss.
What good count would other OEE levels need?
| OEE | Good count | vs now | Performance needed |
|---|
Same planned time and ideal cycle time. Performance needed keeps today's availability and quality.
How your OEE is worked out
OEE = availability × performance × quality. It is the share of planned time spent making good parts at full speed.
- 1
Availability
375 min ran÷ 420 min planned= 89.29%
- 2
Performance
13,500 × 1.5 s= 337.5 min ÷ 375= 90%
- 3
Quality
13,230 good÷ 13,500 made= 98%
- 4
OEE
89.29% × 90%× 98%= 78.75%
Read more: the formula, a worked example, the six big losses, TEEP and notes
OEE (overall equipment effectiveness) compares what a machine or line really made with what it could have made if it ran at full speed, never stopped and made no bad parts, during the time you planned to produce. 100% would be perfect production. It splits into three factors: availability (stops), performance (speed) and quality (rejects).
The formula
run time = planned production time − downtime
availability = run time ÷ planned production time
performance = (ideal cycle time × total count) ÷ run time
quality = good count ÷ total count
OEE = availability × performance × quality
simple formula: OEE = (good count × ideal cycle time) ÷ planned production time
ideal cycle time = 1 ÷ ideal rate
planned production time = number of shifts × (shift length − breaks − other time with no production planned)
net run time = ideal cycle time × total count
fully productive time = ideal cycle time × good count
availability loss = downtime = unplanned stops + planned stops
performance loss = run time − net run time = small stops + slow cycles
quality loss = net run time − fully productive time = (production rejects + startup rejects) × ideal cycle time
utilisation = planned production time ÷ all time
TEEP = OEE × utilisation
good count for a target = target OEE × planned production time ÷ ideal cycle time
Worked example
A line has 420 minutes of planned production time and 45 minutes of downtime. Its ideal cycle time is 1.5 seconds a part (0.025 minutes, or 2,400 parts an hour). It made 13,500 parts, of which 13,230 were good.
Run time = 420 − 45 = 375 min. Availability = 375 ÷ 420 = 89.29%.
Net run time = 13,500 × 0.025 = 337.5 min. Performance = 337.5 ÷ 375 = 90%.
Quality = 13,230 ÷ 13,500 = 98%.
OEE = 0.892857 × 0.9 × 0.98 = 78.75%. The simple formula agrees: 13,230 × 1.5 s = 19,845 s, and 19,845 ÷ 25,200 s (420 min) = 78.75%.
Fully productive time = 13,230 × 0.025 = 330.75 min. The losses add back up: 45 (stops) + 37.5 (speed: 375 − 337.5) + 6.75 (rejects: 270 × 0.025) + 330.75 = 420 min. At full speed with no stops it could have made 420 ÷ 0.025 = 16,800 parts, so 16,800 − 13,230 = 3,570 good parts were lost.
The same line in Advanced mode
Shift builder: one 8-hour shift (480 min) with 60 minutes of breaks: 480 − 60 = 420 min planned.
Downtime by reason: breakdowns 20 + waiting for material 10 = 30 min of unplanned stops, and changeovers 15 min of planned stops: 45 min in all.
Six big losses: of the 37.5 min speed loss, 12 min were small stops, so 37.5 − 12 = 25.5 min were slow cycles. Of the 270 rejects, 70 were startup rejects (70 × 1.5 s = 105 s = 1.75 min) and 200 production rejects (200 × 1.5 s = 300 s = 5 min).
TEEP: with 24 hours (1,440 min) in the day, utilisation = 420 ÷ 1,440 = 29.17%, and TEEP = 78.75% × 29.17% = 22.97%.
Target of 85%: good count needed = 0.85 × 420 ÷ 0.025 = 14,280, which is 1,050 more than now. Keeping availability and quality as they are, performance would need to be 0.85 ÷ (0.892857 × 0.98) = 0.85 ÷ 0.875 = 97.14%. Keeping performance and quality as they are, availability would need to be 0.85 ÷ (0.9 × 0.98) = 96.37%, a run time of 404.76 min, so downtime could be at most 420 − 404.76 = 15.24 min.
The six big losses
| Loss | Classic name | Cuts | Examples |
|---|---|---|---|
| Unplanned stops | Equipment failure | Availability | Breakdowns, no material, no operator |
| Planned stops | Setup and adjustments | Availability | Changeovers, cleaning, tool changes |
| Small stops | Idling and minor stops | Performance | Jams, blocked sensors, short stops |
| Slow cycles | Reduced speed | Performance | Running below ideal speed, worn parts |
| Production rejects | Process defects | Quality | Scrap and rework in steady running |
| Startup rejects | Reduced yield | Quality | Bad parts after a start or changeover |
Notes
- Ideal cycle time should be the fastest the machine can sustain for that part (its design speed, or the best you have seen). If it is set too slow, performance can come out over 100%; the calculator warns you.
- Good count means right first time. Parts that need rework count as rejects, even if they are sold later.
- Planned stops such as changeovers are usually counted as downtime, so they lower availability. Time with no production planned at all (no orders, planned maintenance, meetings) is left out of planned production time, and only shows up in TEEP.
- Benchmarks: 85% is a commonly quoted benchmark for OEE, not a standard. What is realistic varies a lot between processes, so compare with your own line over time, counting planned time the same way each time.
- OEE suits one machine or line making parts with a known ideal cycle time. With several products, work out each run separately, or use the ideal cycle time of each part when you add up net run time.
Standard OEE definitions (availability × performance × quality, as set out by Seiichi Nakajima and used in ISO 22400-2). Results are a guide to where time is lost.
Common questions
How do you calculate OEE?
OEE = availability × performance × quality. Availability = run time ÷ planned production time; performance = (ideal cycle time × total count) ÷ run time; quality = good count ÷ total count. With 420 minutes planned, 45 minutes of downtime, an ideal cycle time of 1.5 seconds, 13,500 parts made and 13,230 good, OEE = 89.29% × 90% × 98% = 78.75%.
Is there a quicker way to work out OEE?
Yes: OEE = (good count × ideal cycle time) ÷ planned production time. It gives exactly the same answer as multiplying the three factors. 13,230 × 1.5 s = 19,845 s, and 19,845 ÷ 25,200 s (420 minutes) = 78.75%. The three factors are still worth working out, because they show where the time was lost.
What are the six big losses?
The six reasons OEE falls short of 100%: unplanned stops (equipment failure) and planned stops (setup and adjustments) cut availability; small stops (idling and minor stops) and slow cycles (reduced speed) cut performance; production rejects (process defects) and startup rejects (reduced yield) cut quality.
What is the difference between OEE and TEEP?
OEE measures how well you use the time you planned to produce. TEEP measures how well you use all the time there is (24 hours a day, every day): TEEP = OEE × utilisation, where utilisation = planned production time ÷ all time. One 7-hour shift in a 24-hour day is a utilisation of 29.17%, so an OEE of 78.75% is a TEEP of 22.97%.
What is a good OEE score?
An OEE of 85% is a commonly quoted benchmark, not a standard: what is realistic depends a lot on the process, the product mix and how you count planned time. The most useful comparison is with your own line over time, using the same rules each time.
Why is my performance over 100%?
The ideal cycle time you entered is slower than the machine really runs, or some downtime was counted twice. Use the fastest cycle time the machine can sustain (its design or nameplate speed, or the best you have seen), and performance will come out at 100% or less.
Related calculators
Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.