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5. How to calculate Availability (and OEE) when a shift is not completed yet?

Q: What is the availability (or OEE) of a shift when the shift is not completed yet?

In the book ‘OEE for the production team‘, you mention the shift time as the basis for the calculation.


I entered some data in our OEE software (OEE Toolkit v6). It looks like the availability is calculated based on the time which was actually registered (see Pic below).

availability screen

So here it takes the 15 minutes the shift is on its way as 100%. Now 26,7% of that time the machine was running.

But in the book, you mention the shift time as the basis for the calculation.
So I expected the total shift-duration (510 min) would be the reference value for the availability.

In that case, 4 min out of 510 would be the availability (0,8%)

When is the full scheduled shift time taken into account?

Arno Koch • The question you raise is: How is OEE calculated during a shift?

If the OEE is to be calculated for a shift, (let’s say a shift with a duration of 510 minutes), what then is the OEE after 120 minutes?

2 Strategies

Here we can follow 2 strategies:

1. Take the 120 minutes as 100% and calculate OEE
2. Take the 510 minutes of the shift as 100% and calculate OEE

In the situation 1, typically OEE jumps up when running and drops down again when idling.
In situation 2, OEE will start low and gradually evolves to its final value.

I prefer situation 2 since it is more intuitive to the operators. After a while they know what is a normal and what is an abnormal behavior of the number.
If well presented in a graphical manner, the team sees the ‘still to go’ part of time melt away, and the OEE pattern appears.
It is easier to steer upon than a number that has no reference point in time, other than ‘now’ and that jumps up and down.

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