Reliability and uptime
Equipment availability calculator
Availability is the share of planned production time that the asset was actually able to run. It is the first of the three OEE factors, and it captures unplanned stops only: breakdowns, waiting on parts, waiting on an operator.
Availability = (Planned production time − Unplanned downtime) ÷ Planned production time × 100
Time the asset was scheduled to run over the period
Breakdowns and unplanned stops only, not scheduled maintenance
Show the assumptions
- Formula
- Availability = (Planned production time − Unplanned downtime) ÷ Planned production time × 100
Everything here turns on what you count as planned production time. Excluding a shift you chose not to run is correct. Excluding a shift you could not run because the machine was down is not. That hides the loss you are trying to measure.
Availability
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Prefilled with an example. Change any number and the result updates.
How to calculate Availability
Availability = (Planned production time − Unplanned downtime) ÷ Planned production time × 100
Worked example
- Planned production time 160 hrs
- Unplanned downtime 16 hrs
Availability = 90.0%
Reading the result
Everything here turns on what you count as planned production time. Excluding a shift you chose not to run is correct. Excluding a shift you could not run because the machine was down is not. That hides the loss you are trying to measure.
Benchmarks
90% is the availability figure commonly cited as world class within the OEE framework.
Availability questions
Does scheduled maintenance count against availability?
Not in the OEE definition. Planned maintenance is removed from planned production time, so it neither helps nor hurts the figure. If you want a number that does include it, calculate asset utilization against calendar hours instead.
What is the difference between availability and uptime?
Uptime is usually quoted against calendar time, availability against planned production time. An asset you run one shift a day can be 95% available and 32% up, and both numbers are correct. Say which denominator you used whenever you report either.
How does availability relate to MTBF and MTTR?
Availability can also be derived as MTBF ÷ (MTBF + MTTR). That form is useful when you track failure and repair times but not production schedules, and it answers a slightly different question: inherent availability of the asset rather than availability of the planned schedule.
Related calculators
See downtime by asset
UpKeep records the work, the hours and the failures this metric depends on, so Availability is a report rather than a spreadsheet exercise.