What is OEE?

OEE (Overall Equipment Effectiveness) is a single percentage that tells you how much of your planned production time was truly productive. It combines three factors - availability, performance and quality - into one number, so a machine that runs at 100% OEE makes only good parts, as fast as it possibly can, with no stop time. Most lines run far lower than their managers think.

OEE is the most widely used measure of manufacturing productivity because it turns a messy shift - breakdowns, slow running, changeovers, scrap - into one comparable figure you can track over time and across lines. We calculate it to the ISO 22400-2 standard, so the number holds up in any review.

The OEE formula

OEE is the product of three factors, each a percentage between 0 and 100%:

Because the three are multiplied, OEE is unforgiving: 90% on each factor is not 90% overall - it's 0.9 × 0.9 × 0.9 = 73%. That's the point. A line is only as effective as the combination of all three, and small losses compound fast.

The three factors

1. Availability - was it running?

Availability is the share of planned production time the machine was actually running. It's cut down by every stop: breakdowns, material shortages, and changeovers.

2. Performance - was it running at full speed?

Performance is how fast the line ran while it was running, against its ideal cycle time. It captures the losses you can't see on a downtime report: minor stops, jams cleared in seconds, and running below rated speed.

3. Quality - was the output good?

Quality is the share of produced units that were good the first time. Rework counts as a defect - if it didn't leave the line right, it's a quality loss.

A worked example

Take one 8-hour shift on a single line:

• Planned production time: 480 minutes. Stops totalled 80 minutes, so run time was 400 minutes → Availability = 400 ÷ 480 = 83.3%.
• At its ideal cycle time the line could have made 24,000 parts in those 400 minutes; it made 19,200 → Performance = 19,200 ÷ 24,000 = 80%.
• Of the 19,200 parts, 18,816 were good → Quality = 18,816 ÷ 19,200 = 98%.

A 65% OEE is typical - and it means roughly a third of paid production time produced nothing of value. See the full method in how to calculate OEE.

What's a good OEE?

As a rule of thumb, 85% is considered world-class for discrete manufacturing, ~60% is typical, and below 40% there's usually a lot of room to improve. But the benchmark depends heavily on your industry and how honestly you set planned time - read what is a good OEE score before you compare.

Why OEE is worth measuring

OEE's real value isn't the score - it's the breakdown. When availability, performance and quality are tracked separately, and every stop is captured with a reason, you can see exactly where time is lost and attack the biggest cause first. Those causes are well understood: they're the Six Big Losses, and most downtime traces back to just a few of them. That's the whole game - measure honestly, then remove the losses that cost you most.