How do you calculate OEE?

OEE is availability × performance × quality. Availability is run time divided by planned production time, performance is ideal cycle time × total count divided by run time, and quality is good count divided by total count. Multiplied together they equal good count × ideal cycle time divided by planned production time: the share of planned time spent making good units at full speed.

What is a good OEE score?

85% is commonly cited as world-class OEE for discrete manufacturing. Treat it as a reference point rather than a target for every line: product mix, changeover frequency and how a plant defines planned downtime all move the number. The most useful comparison is usually the same line over time, calculated the same way.

What is the difference between availability and performance?

Availability counts the time the machine was stopped when it was planned to run: breakdowns, changeovers, waiting for material. Performance counts the speed lost while it was running: slow cycles and short stops nobody logged as downtime. A stop logged as downtime lowers availability; the same stop left unlogged shows up as lower performance.

Where do micro-stops show up in OEE?

Stops too short to be logged as downtime still cost output, so they appear as a performance loss: the machine looks as if it ran for the whole run time but made fewer units than its ideal cycle time allows. Catching them needs machine states read far more often than a manual log can record, which is why short stops are often under-reported on paper.

Can I calculate OEE in Excel?

Yes. The calculator’s Excel template lists your inputs and calculates planned production time, run time, good count, availability, performance, quality and OEE with plain formulas you can copy for every shift. The file is a CSV, so it also opens in LibreOffice and Google Sheets.

Free tool

OEE calculator

Work out OEE for a shift, a line or a week. Enter the time, the stops, the ideal speed and the counts; the calculator shows availability, performance, quality and OEE with the formula behind each one.

OEE = Availability × Performance × Quality

Time

Shift length (min)

The whole period you are measuring: a shift, a day or a week.

Planned downtime (min)

Breaks, meetings, planned maintenance. Not counted as a loss.

Unplanned downtime (min)

Breakdowns, changeovers, waiting for material: stops while the machine was meant to run.

Speed

Ideal cycle time (s per unit)

The fastest time per unit the machine can sustain for this product.

Output

Total count (units)

Every unit made, good and rejected.

Reject count (units)

Scrap and rework: units that were not right first time.

OEE

87.4% × 86.8% × 98.0%

74.3%

10.7 points below the commonly cited 85% world-class reference.

Availability

87.4%

380 ÷ 435 min

Performance

86.8%

13,200 ÷ 15,200 units at ideal speed

Quality

98.0%

12,936 ÷ 13,200 units

Planned production time: 435 min
Run time: 380 min
Good count: 12,936 units

The formulas

How to calculate OEE

OEE (overall equipment effectiveness) is the share of planned production time spent making good units at the ideal speed. It splits the losses into three factors, so you can see whether time, speed or quality is costing you most.

Planned production time: Shift length − Planned downtime
Run time: Planned production time − Unplanned downtime
Availability: Run time ÷ Planned production time
Performance: (Ideal cycle time × Total count) ÷ Run time
Quality: Good count ÷ Total count
OEE: Availability × Performance × Quality

The three factors multiply out to a shortcut: OEE = (Good count × Ideal cycle time) ÷ Planned production time. Use it to check a result.

Worked example

An OEE calculation, step by step

One 480-minute shift on one machine: 45 minutes of planned breaks, 55 minutes of unplanned stops, an ideal cycle time of 1.5 seconds per unit, 13,200 units made and 264 of them rejected. These are the values the calculator opens with.

01 Planned production time 480 − 45 = 435 min
02 Run time 435 − 55 = 380 min
03 Availability 380 ÷ 435 = 87.4%
04 Performance (1.5 s × 13,200) ÷ (380 min × 60) = 19,800 ÷ 22,800 = 86.8%
05 Quality (13,200 − 264) ÷ 13,200 = 12,936 ÷ 13,200 = 98.0%
06 OEE 87.4% × 86.8% × 98.0% = 74.3%

What the result means

85% is commonly cited as world-class OEE for discrete manufacturing. The example, at 74.3%, sits below it, and the factors show where to look first: availability (87.4%) and performance (86.8%) lose far more than quality (98.0%). Treat 85% as a reference point, not a target for every line; the most useful comparison is usually the same line over time, calculated the same way.

Beyond the spreadsheet

From a calculator to live OEE

A calculator works on numbers someone wrote down after the shift. Proxus reads cycle counters, machine states, reject counts and downtime signals directly from the controllers, and the built-in OEE tracker function template calculates availability, performance, quality and OEE on the gateway, the same way on every line and site.

Try Proxus on your machines See OEE monitoring

Downtime captured with the signals around it, not just a duration.
Live line status for operators, aggregated performance for management.
Scheduled reports and feeds to MES or BI from the same data.

Questions

OEE questions, answered.

How do you calculate OEE?: OEE is availability × performance × quality. Availability is run time divided by planned production time, performance is ideal cycle time × total count divided by run time, and quality is good count divided by total count. Multiplied together they equal good count × ideal cycle time divided by planned production time: the share of planned time spent making good units at full speed.
What is a good OEE score?: 85% is commonly cited as world-class OEE for discrete manufacturing. Treat it as a reference point rather than a target for every line: product mix, changeover frequency and how a plant defines planned downtime all move the number. The most useful comparison is usually the same line over time, calculated the same way.
What is the difference between availability and performance?: Availability counts the time the machine was stopped when it was planned to run: breakdowns, changeovers, waiting for material. Performance counts the speed lost while it was running: slow cycles and short stops nobody logged as downtime. A stop logged as downtime lowers availability; the same stop left unlogged shows up as lower performance.
Where do micro-stops show up in OEE?: Stops too short to be logged as downtime still cost output, so they appear as a performance loss: the machine looks as if it ran for the whole run time but made fewer units than its ideal cycle time allows. Catching them needs machine states read far more often than a manual log can record, which is why short stops are often under-reported on paper.
Can I calculate OEE in Excel?: Yes. The calculator’s Excel template lists your inputs and calculates planned production time, run time, good count, availability, performance, quality and OEE with plain formulas you can copy for every shift. The file is a CSV, so it also opens in LibreOffice and Google Sheets.