OEE Calculator — Overall Equipment Effectiveness

OEE — Overall Equipment Effectiveness — is the standard measure of how much of a machine's potential a manufacturing process actually captures. It rolls the three ways a line loses output into one percentage: time lost to stops (availability), speed lost while running (performance), and output lost to defects (quality). An OEE of 100% means producing only good parts, as fast as theoretically possible, with zero unplanned stops.

Plant managers, production supervisors, and continuous-improvement teams use OEE as the headline metric for TPM (Total Productive Maintenance) and Lean programs, because one number that decomposes into three named causes tells you not just that a line underperforms but where to look first.

OEE = Availability × Performance × Quality

Each factor is a ratio of time or count actually achieved to the ideal:

Availability = Run Time ÷ Planned Production Time
Performance  = (Ideal Cycle Time × Total Count) ÷ Run Time
Quality      = Good Count ÷ Total Count

Planned production time is scheduled time minus planned stops (breaks, scheduled maintenance); run time is what remains after unplanned downtime. Ideal cycle time is the theoretical fastest time per unit — the design speed, not the average speed. The factors multiply, which is why OEE drops quickly: three respectable-sounding 90% factors compound to just 72.9% OEE.

A packaging line runs an 8-hour shift (480 minutes) with 30 minutes of planned breaks, leaving 450 minutes of planned production time. Breakdowns and changeovers eat 45 minutes of that. The line's ideal cycle time is 0.5 minutes per unit; it produces 750 units, of which 720 pass first-time quality.

Availability = (450 − 45) ÷ 450        = 405 ÷ 450 = 90.0%
Performance  = (0.5 × 750) ÷ 405       = 375 ÷ 405 = 92.6%
Quality      = 720 ÷ 750               = 96.0%
OEE          = 0.900 × 0.926 × 0.960   = 80.0%

80% OEE is a strong result — above typical, short of world class. The Six Big Losses breakdown shows where the 120 lost minutes went: 30 to planned stops, 45 to breakdowns and changeovers, 30 to minor stops and reduced speed, and 15 to the 30 defective units. Only 360 of the 480 shift minutes produced sellable output.

World class is more demanding than “85% overall”: the TPM literature defines it as availability ≥ 90%, performance ≥ 95%, and quality ≥ 99.9% simultaneously — which multiply to about 85%. This calculator rates your result against those same factor-level targets, so an 86% OEE built on 99% quality reads as typical, not world class.

The Six Big Losses are the classic TPM partition of everything that separates actual output from perfect production. Each loss erodes exactly one OEE factor, which is what makes the breakdown actionable:

Availability losses — equipment breakdowns and setup/changeover time. The line is scheduled to run but is not running. Performance losses — minor stops (jams, misfeeds cleared in seconds) and reduced-speed running. The line is running, but slower than its ideal cycle time. Quality losses — startup rejects produced while the process stabilizes, and defects during steady-state production. The line is running at speed, but some output cannot be sold.

This calculator expresses each loss in minutes of the shift, so the biggest bar is, literally, the biggest recovery opportunity — the natural starting point for a kaizen event or a DMAIC project.

OEE deliberately forgives planned stops: it judges equipment against the time you chose to run it. TEEP — Total Effective Equipment Performance — removes that forgiveness by measuring against total scheduled time including planned stops, and in its strictest form against the full 24/7 calendar (a week has 10,080 minutes whether you schedule them or not).

The two answer different questions. OEE asks “how well do we run when we run?” — the operations question. TEEP asks “how much of this asset's total capacity are we using?” — the capital question. A line at 80% OEE but 40% TEEP does not need a better machine; it needs more scheduled hours on the machine it has. That is why TEEP often justifies adding a shift before it justifies adding equipment.