A single OEE number says little. Only when you see whether the loss is in downtime, in speed or in rejects do you know where to start. That is why this calculator works out all three.
Calculate your OEE
- Availability80.0%
- Performance83.3%
- Quality95.0%
Biggest loss: availability, 90 minutes.
How the calculator works
- Planned production time = shift length − planned stops
- Availability = (planned production time − unplanned downtime) ÷ planned production time
- Performance = (ideal cycle time × total produced) ÷ run time
- Quality = good units ÷ total produced
The default values come from the worked example in calculating OEE: a 480-minute shift with 90 minutes of breakdowns comes out at 63.3%.
The loss in minutes
The calculator translates each factor back into minutes. In the example: 90 minutes of downtime, 60 minutes of speed loss and 15 minutes of rejected products. Together 165 of the 450 minutes. At a glance you can see that tackling a breakdown pays off more here than the rejects.
Performance above 100%
If performance comes out above 100%, the ideal cycle time is set too generously. That often happens when someone enters the average time instead of the fastest achievable one. Use the machine’s design speed, or the best time the line demonstrably achieves.
From one shift to a trend
A calculator gives a snapshot, and the input comes from someone’s notes. The real gain is in the trend per shift and per downtime cause. How to record those causes is covered in recording downtime.
VDS reads downtime and counts automatically from the machines, through standard protocols such as OPC UA and Modbus or with separate sensors. The data stays in your own environment. VDS supplies the measurement layer; what you improve with the figures remains your decision.
Frequently asked questions
How do I calculate OEE?
Multiply availability, performance and quality. In the calculator you enter shift length, planned stops, unplanned downtime, ideal cycle time, total produced and good units.
What data do I need?
Six numbers per shift: shift length, planned stops, unplanned downtime, ideal cycle time per unit, the total number of units produced and the number of good units.
Why does my performance come out above 100%?
Then the ideal cycle time is set too generously. Enter the fastest achievable time per unit, not the average.
What is a good OEE?
85% is considered world class; 40–60% is common in discrete manufacturing. The trend and the split across the three factors say more than the absolute value.
Can I use the calculator for a whole factory?
Calculate per line or machine. A factory average hides exactly the differences where the gain is.
