Guide10 min read

OEE explained: measurement, analysis and improvement

OEE is the most widely used measure of production efficiency. But most companies measure it wrong — or never use the data to drive improvement. This guide gives you the full picture.

OEE stands for Overall Equipment Effectiveness and measures how effectively your production equipment is used. An OEE of 85% means you get only 85% of the theoretically possible output out of your equipment. The remaining 15% disappears into stoppages, speed losses and quality defects.

The OEE formula

OEE = Availability × Performance × Quality

All three factors are measured as percentages (0-100%)

Availability

Run time / Planned production time

Losses: breakdowns, changeovers, material shortages

Performance

Actual output / Theoretical output

Losses: reduced speed, micro-stops, idling

Quality

Good units / Total produced

Losses: scrap, rework, start-up waste

Example of an OEE calculation

Let's say you have an 8-hour shift (480 min) on a machine:

Availability87.5%

Planned: 480 min. Stoppages: 60 min (breakdowns + changeover). Run time: 420 min.
420 / 480 = 87.5%

Performance90%

Ideal cycle time: 0.5 min/unit. In 420 min we should make 840 units. We made 756.
756 / 840 = 90%

Quality98%

Produced: 756 units. Scrapped/reworked: 15 units. Good: 741 units.
741 / 756 = 98%

Overall OEE

77.2%

0.875 × 0.90 × 0.98 = 0.772

OEE benchmarks: how good is your OEE?

<65%

Low

Significant improvement potential. Start by identifying the biggest loss categories.

65-75%

Average

Typical for many manufacturers. A solid base to build on.

75-85%

Good

Above average. Focus on reducing variation and eliminating the last big losses.

>85%

World Class

You are among the best. Hold the level and work on fine-tuning.

The six big losses

The OEE methodology identifies six main categories of loss. Understanding them is the key to improvement:

Availability

1. Breakdowns

Unplanned stoppages due to equipment failure

2. Setup and adjustment

Changeover, product changes, cleaning

Performance

3. Idling and micro-stops

Short stops (<5 min) that often go unrecorded

4. Reduced speed

Running slower than design speed

Quality

5. Start-up waste

Scrap during start-up/ramp-up

6. Production defects

Defects during stable operation

How to improve your OEE

Measure correctly and consistently

Define precisely what counts as planned production time, what counts as a stoppage, and what the ideal cycle time is. Use the same definitions every time.

Run a Pareto analysis on the losses

Categorise all losses and prioritise by size. Typically 20% of the causes account for 80% of the losses. Start with the biggest.

Attack one loss category at a time

Many breakdowns? Implement TPM. Long changeover time? Use SMED. Micro-stops? Look at standard work and autonomation.

Make OEE visible to everyone

Show OEE daily at the machine/line. When operators can see the effect of stoppages and losses, they start acting on it.

Common mistakes in OEE measurement

×Using an unrealistic cycle time — Use the speed the machine can actually run stably, not the fastest it ever ran.
×Excluding planned stoppages — Breaks, meetings and maintenance should be deducted from planned time, not counted as loss.
×Ignoring micro-stops — Stops under 5 minutes often add up to more than the big breakdowns.
×Measuring without acting — OEE without follow-up is just a number. Use it in Daily Management.

Calculate your OEE now

Use our free OEE calculator to work out your OEE and see where you lose capacity.

Open the OEE calculator