Availability is the first factor of OEE. It is the share of planned production time that the equipment was actually running, after you subtract every stop.
The Availability formula
Availability = Run Time / Planned Production Time
Step by step
- Set Planned Production Time. Start from the time the equipment was scheduled to run, excluding planned non-production time such as no demand or no shift.
- Add up all stop time. Sum every stop within planned time: breakdowns, changeovers, setup, waiting and small stops.
- Calculate Run Time. Run Time = Planned Production Time minus total stop time.
- Divide. Availability = Run Time / Planned Production Time, expressed as a percentage.
A worked example
An 8-hour shift gives 480 minutes of planned time. The line lost 35 minutes to a changeover and 25 minutes to breakdowns (60 minutes total):
| Step | Calculation | Result |
|---|---|---|
| Stop time | 35 + 25 | 60 min |
| Run Time | 480 - 60 | 420 min |
| Availability | 420 / 480 | 87.5% |
Our free OEE Calculator does this live, with the benchmark overlay.
Common mistakes
- Forgetting changeover and setup time, which are availability losses.
- Including planned non-production time in the denominator (it should be excluded).
- Ignoring small stops because they are hard to log.
Availability FAQ
Do changeovers count against availability?
Yes. Changeover and setup are availability losses within planned production time.
What is a good availability?
World-class OEE assumes roughly 90 percent availability, but it varies widely by process and changeover load.
Where do micro-stops go?
Very short stops often fall into Performance rather than Availability, depending on how you log them. The key is to capture them somewhere.
Related: OEE · planned vs unplanned downtime · micro-stops