Short answer: the Six Big Losses are the standard framework for the productivity losses that OEE measures. They map to the three OEE factors: two Availability losses (breakdowns; setup & changeovers), two Performance losses (idling & minor stops; reduced speed) and two Quality losses (process defects & rework; reduced yield & startup losses). Eliminating them — biggest first — is how you raise OEE.
| Big Loss | OEE factor | Typical cause | How to eliminate |
|---|---|---|---|
| 1. Breakdowns | Availability | Equipment failure, unplanned stops | Condition monitoring, preventive maintenance |
| 2. Setup & changeovers | Availability | Long product/tool changes | SMED, standardised changeover |
| 3. Idling & minor stops | Performance | Micro-stops, jams, sensor trips | Automatic micro-stop detection, root-cause |
| 4. Reduced speed | Performance | Running below ideal cycle time | Address slow cycles, wear, settings |
| 5. Process defects & rework | Quality | Out-of-spec output in steady state | Mistake-proofing, first-pass-yield tracking |
| 6. Reduced yield & startup | Quality | Scrap during warm-up/changeover | Optimise startup, reduce ramp scrap |
Why the Six Big Losses matter
OEE tells you how much productivity you are losing; the Six Big Losses tell you where. Introduced in Total Productive Maintenance (TPM), the framework turns an abstract percentage into six concrete, attackable problems, each tied to one of the three OEE factors. That makes it the natural bridge from measuring OEE to improving it — see our guide to improving OEE.
Availability losses: breakdowns and changeovers
Breakdowns (Loss 1) are unplanned stops from equipment failure — usually the single largest loss — reduced with condition monitoring and preventive maintenance based on real runtime. Setup and changeovers (Loss 2) are recoverable capacity: apply SMED (Single-Minute Exchange of Die) to separate internal from external steps and standardise the sequence.
Performance losses: minor stops and reduced speed
Idling and minor stops (Loss 3) are short stoppages — jams, misfeeds, sensor trips — that are almost impossible to catch on a clipboard. Automatic micro-stop detection logs every one so you can attack recurring causes. Reduced speed (Loss 4) is running below the ideal cycle time, often from wear, sub-optimal settings or cautious operation.
Quality losses: defects and startup scrap
Process defects and rework (Loss 5) are out-of-spec parts produced in steady state — they cost twice, once in scrap and again in rework. Reduced yield and startup losses (Loss 6) are the scrap produced during warm-up and after changeovers, which is often underestimated. Track first-pass yield by line and shift to expose both.
How to prioritise
Rank the six losses by lost time or lost units and fix the biggest one or two first, rather than spreading effort thin. Automatic, time-stamped loss data makes this objective — compare platforms in our 2026 OEE software guide, and benchmark your result against the 2026 sector benchmarks.
See TeepTrak pinpoint your Six Big Losses — book a demo
Frequently asked questions
What are the Six Big Losses in OEE?
Breakdowns and setup/changeovers (availability); idling/minor stops and reduced speed (performance); and process defects/rework plus reduced yield/startup losses (quality).
Which of the Six Big Losses is most costly?
It varies by plant, but unplanned breakdowns and unrecorded minor stops are the most common top losses. Ranking them by measured lost time is the only reliable way to know.
How do the Six Big Losses map to OEE?
Two losses reduce Availability, two reduce Performance, and two reduce Quality — the three factors that multiply together to give OEE.
How do you eliminate the Six Big Losses?
Measure them automatically, rank by impact, then apply the right countermeasure: preventive maintenance and SMED for availability, micro-stop analysis for performance, and mistake-proofing for quality.
From losses to gains: once you can name the Six Big Losses, the next step is eliminating them. See the playbook in our guide to improving OEE — 8 proven ways.
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