Metrics & analysisOverall Equipment Effectiveness

What is OEE?

OEE (Overall Equipment Effectiveness) measures how large a share of the planned production time actually produces good parts. OEE = Availability × Performance × Quality. World class is reckoned at ≈ 85%; typical unoptimised plants sit around 60% (Nakajima, 1988).

The three factors each isolate a type of loss: Availability captures stops (breakdowns, changeovers), Performance captures speed loss (reduced pace, minor stops), Quality captures defective parts and start-up scrap. An OEE of 60% means 40% of the planned time is lost — typically without anyone being able to see where.

OEE’s value is not the number but the conversation: a shared, honest definition of loss makes capacity waste visible and prioritisable. The classic mistake is to “dress up” OEE by moving losses outside planned time.

Calculate your OEE

Related concepts

The six big losses

The six big losses are TPM’s classic categorisation of equipment losses: (1) breakdowns, (2) changeover and adjustment, (3) minor stops, (4) reduced speed, (5) start-up defects and (6) process defects/scrap. The three pairs correspond to OEE’s three factors: availability, performance and quality.

Availability

Availability is OEE’s first factor: the share of the planned production time in which the equipment is actually running. Availability = running time ÷ planned production time. Losses: breakdowns, changeovers and other stops.

TPM

TPM (Total Productive Maintenance) is a systematic approach to maximising equipment effectiveness by making maintenance a shared responsibility — operators perform daily basic maintenance (autonomous maintenance), while technicians focus on prevention and improvement.

Bottleneck

The bottleneck is the process in a chain with the lowest capacity, which thereby limits the throughput of the entire system. An hour lost at the bottleneck is an hour lost for the whole factory — capacity gained everywhere else is an illusion.

From concept to practice

The methods only work when they are anchored in daily routines and leadership behaviour. The operations check shows in 4 minutes where your operations stand — and what the next step is.

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