Definition
Downtime is the total time an asset is not performing its intended function, counted from the moment it stops to the moment it resumes, encompassing both planned stops (maintenance, changeover) and unplanned stops (failure). It is the umbrella time measure that planned downtime and unplanned downtime each account for a portion of.
Key facts
- The umbrella measure of all non-productive time, whatever the cause, planned or unplanned.
- Requires a clear, consistently applied start and stop definition (e.g., from the moment production stops to first good output) to be comparable over time.
- Split into planned downtime (scheduled, agreed reason) and unplanned downtime (unexpected failure) for meaningful analysis.
- The complement to uptime: together they account for total available time.
How is Downtime calculated?
Downtime measures the total elapsed time an asset was not performing its intended function, from a consistently applied stop event to a consistently applied resume event, capturing both planned reasons like maintenance and unplanned reasons like unexpected failure within one total figure.
How it differs from unplanned downtime and uptime
Downtime is the total figure; unplanned downtime is specifically the portion caused by unexpected failure, as distinct from planned downtime's scheduled portion. Uptime is downtime's complement (the time the asset was actually performing its function) and together uptime and downtime account for the full period under measurement.
FAQ
Frequently asked questions
Which time counts as downtime?
All time an asset is not performing its intended function, from the moment it stops to the moment it resumes, encompassing both planned reasons (maintenance) and unplanned reasons (unexpected failure).
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