TAHA Engineering Toolsby TAHA Knowledge Lab

Industrial & Manufacturing

OEE Calculator

Overall Equipment Effectiveness from availability, performance and quality.

Inputs

Four horizontal bars: planned production time, run time after stops, net run time after slow running, and fully productive time after defects.Planned production timeRun time− stops → ANet run time (ideal speed)− slow → PFully productive time− defects → QOEE = fully productive time ÷ planned production time
Each bar is shorter than the one above by one type of loss: stops reduce availability (A), slow running reduces performance (P) and defects reduce quality (Q). OEE = A × P × Q. Diagram not to scale.

Shift time minus planned stops such as breaks and planned maintenance.

Breakdowns, changeovers, waiting for material, etc.

The fastest possible time to make one part under ideal conditions.

Parts that passed first time, without rework.

Result

OEE
74.79%
Availability
88.81%
Performance
86.11%
Quality
97.8%
Run time
373

OEE is 74.79%: that share of the planned time was fully productive (good parts at ideal speed with no stops). The largest loss is in performance (86.11%), so improvement work there will raise OEE the most.

Educational estimate — check the assumptions below.

About this calculator

Overall Equipment Effectiveness (OEE) measures how much of the planned production time is truly productive. It multiplies three losses: availability (time lost to stops), performance (running slower than the ideal speed) and quality (parts that are not good first time). OEE is a key measure in Total Productive Maintenance (TPM) and lean manufacturing.

Formula

OEE = A × P × Q

  • Run time = Planned production time − Downtime
  • A = Run time ÷ Planned production time
  • P = (Ideal cycle time × Total count) ÷ Run time
  • Q = Good count ÷ Total count

A useful check: OEE also equals (Good count × Ideal cycle time) ÷ Planned production time.

Worked example

A shift has 420 min of planned production time and 47 min of unplanned stops. The ideal cycle time is 1.0 s. The machine made 19,271 parts, of which 18,848 were good.

  • Run time = 420 − 47 = 373 min = 22,380 s
  • Availability = 373 ÷ 420 = 88.81%
  • Performance = (1.0 × 19,271) ÷ 22,380 = 86.11%
  • Quality = 18,848 ÷ 19,271 = 97.81%
  • OEE = 0.8881 × 0.8611 × 0.9781 = 74.79%

Check: (18,848 × 1.0 s) ÷ 25,200 s = 74.79% ✓

Assumptions and limitations

  • Planned production time excludes planned stops (breaks, planned maintenance, no-demand periods), following the common OEE definition. Some companies define it differently — use your company’s definition consistently.
  • All times and counts must cover the same period and the same machine or line.
  • The ideal cycle time should be the theoretical best, not the average. A performance above 100% means the ideal cycle time is set too long.

References

  • Nakajima, S. (1988). Introduction to TPM: Total Productive Maintenance. Productivity Press — origin of the OEE measure.