Plant OEE Calculator

100% FreeRuns in your browserBasic

Enter Values

Availability (%)

Performance (%)

Quality (%)

Enter your values and press Calculate to see results.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

Enter Availability % = actual run (uptime) hours ÷ planned production hours × 100.
Enter Performance % = actual output ÷ (run time × ideal rate) × 100, i.e. how fast the plant ran while operating.
Enter Quality % = good (on-spec) units ÷ total units produced × 100, then read OEE and the loss breakdown.

How it works

Overall Equipment Effectiveness (OEE) rolls the three independent ways a plant loses output into a single figure: OEE = Availability × Performance × Quality, with each factor entered as a percentage from 0 to 100. Because the factors multiply, a plant that scores 90% on each has an OEE of only 0.9 × 0.9 × 0.9 = 72.9%, not 90% — small losses compound. A widely used benchmark is 85% for a 'world-class' discrete operation, though realistic targets vary by plant type and duty.

The loss breakdown attributes the gap from a perfect 100% to each factor in the order they act. Availability loss = (1 − Availability); performance loss is scaled by availability, so it equals Availability × (1 − Performance); quality loss = Availability × Performance × (1 − Quality). These three losses plus the final OEE add back to 100%, which tells you which lever — reducing downtime, lifting throughput rate, or cutting rework/off-spec — will move OEE the most. Enter each factor consistently against the same scheduled-time and ideal-rate baseline.

Worked example

Fixed crusher running at 90% availability, 95% performance, 99% quality. A quarry crushing plant is available 90% of its scheduled time (Availability = 90%), runs at 95% of its ideal throughput while operating (Performance = 95%), and 99% of product is on-spec (Quality = 99%). OEE = 0.90 × 0.95 × 0.99 = 0.8464 = 84.64%. That is just below the 85% world-class benchmark. The loss breakdown shows availability loss of 10.00%, performance loss of 4.50% and quality loss of 0.94% — so downtime is by far the biggest opportunity.

Common mistakes

Averaging the three factors instead of multiplying them — 90/95/99 is not (90+95+99)/3 = 94.7%; OEE multiplies to 84.64%.
Mixing the baselines: measuring Availability against planned time but Performance against a different (e.g. calendar) time or an inflated ideal rate, which can push a factor over 100% and corrupt the OEE.
Double-counting a loss — e.g. treating slow running (a Performance loss) as downtime (an Availability loss), so the same lost tonnes are subtracted twice.

Frequently asked questions

What is a good OEE for a mining or quarry plant?

85% is the common 'world-class' benchmark and 60% is often cited as typical for many operations, but realistic targets depend heavily on plant type, duty and how you define scheduled time and ideal rate. Compare against your own site's historical OEE and OEM design figures rather than a single universal number.

How do I get the three percentages to enter?

Availability = run (uptime) hours ÷ planned production hours × 100. Performance = actual output ÷ (run time × ideal rate) × 100. Quality = good units ÷ total units × 100. Use the same scheduled-time window and a consistent ideal rate for all three.

Why is my OEE so much lower than each individual factor?

Because the factors multiply. Three factors of 90% give 0.9 × 0.9 × 0.9 = 72.9%. This compounding is deliberate — it reflects that a unit of output must survive availability, performance and quality losses in turn.

Does this replace a proper plant-performance analysis?

No. This is a quick estimate to compare periods and find the biggest loss. Verify inputs and conclusions against your site data, OEM specifications and a competent mining professional before acting on them.

Tip: Enter any known values to calculate the remaining results.

All calculations run in your browser. Your inputs are never saved or transmitted.