OEE Calculator
Overall equipment effectiveness from one shift's numbers, broken down into the minutes each loss cost you. OEE is only as honest as the ideal cycle time you give it: set that slow and any machine looks good.
A single percentage hides which loss to work on, so this page shows where the minutes went and which fix is worth the most.
Nothing you type here leaves your browser. Every calculation runs in this page. The page itself counts visits, like every page on this site, but never what you enter.
1. Your shift, and its OEE
Clock time from start to end
Breaks, meetings, planned maintenance
Breakdowns, changeovers, waiting for material
The fastest the machine is designed to run
Good and bad together
Right first time, no rework
2. Where the minutes went
Each loss converted into minutes of planned production time, from the time you planned to run down to the time spent making good units at the ideal rate.
The arithmetic, with your numbers
Shown so you can check it, or redo it in a spreadsheet.
What this does not tell you
- OEE is only as honest as the ideal cycle time. Performance is measured against the cycle time you enter. Enter the rate the line usually runs at, rather than the rate it was designed for, and the speed loss disappears from the figure while it stays on the floor. Use the nameplate rate or the fastest rate the machine has been seen to sustain, and write down which one you used.
- The 85% "world class" figure is a convention, not a benchmark for your machine. It traces to Seiichi Nakajima's writing on total productive maintenance in the 1980s and is quoted far more often than it is measured. A press, a filler and a CNC cell have different natural ceilings. Compare a machine against its own history, not against another plant.
- The answer depends on what you call planned. Moving changeovers or maintenance from unplanned downtime into planned stops raises OEE without changing a single part made. Agree the definitions before comparing two lines, two shifts or two sites.
- One shift is one sample. A single good or bad shift says little. Track OEE and its three losses shift by shift, and act on a loss that stays large, not on one bad day.
- Quality here counts units, not cost. A scrapped unit and a unit reworked in thirty seconds count the same. If rework is expensive, count reworked units as bad, which this page assumes by asking for good units first time through.
- Halving a loss is a what-if, not a forecast. The projection below assumes the other two rates hold while one loss shrinks. In practice, running faster can raise scrap, and fewer stops can mean more start-up rejects.
The rest of the Lean Six Sigma toolkit
- Control Chart Maker: I-MR, c and p Charts with Run Rules: I-MR, c and p charts with the four Western Electric run rules.
- Process Capability Calculator: Cp, Cpk, Pp, Ppk: Cpk with its confidence interval, a Cpk against Ppk drift check and a normality test.
- Sigma Level Calculator: DPMO, yield and how sure you can be: DPMO and sigma level with the 95% interval, and whether a kaizen really cut defects.
- Takt Time and Line Balance Calculator: Takt time, line balance and the bottleneck, with stations that miss takt on slow cycles.