Glossary

What is unplanned downtime?

Quick answer

Unplanned downtime is production time lost to events the plant did not schedule, mainly equipment failures. It is the most expensive form of lost capacity because it combines lost output with emergency labour, expedited parts, and knock-on disruption.

FormulaUnplanned downtime cost = downtime hours x (lost contribution margin per hour + emergency response cost per hour)

Benchmark

Benchmark
GoodWorld-class operations push unplanned downtime toward a low single-digit share of available time.
Warning signDouble-digit unplanned downtime as a share of available time usually means significant, recoverable loss.

Why it matters

Unplanned downtime is where lost revenue and emergency cost meet. A single hour can cost many multiples of the repair itself once lost margin, overtime, and expediting are counted. It is almost always understated because the full cost is spread across production, maintenance, and procurement budgets.

How to improve it

Capture downtime by cause, attack the largest repeat causes with defect elimination, shift spend from reactive to planned, and protect preventive work on critical assets.

Frequently asked questions

How much does unplanned downtime cost?
It depends on the lost contribution margin per hour for that line plus the emergency response cost. In heavy industry the full cost per hour is routinely several multiples of the repair cost. Use a downtime cost calculator with your own margin figure to size it.
What is the difference between planned and unplanned downtime?
Planned downtime is scheduled in advance for maintenance or changeovers, so it can be resourced and minimised. Unplanned downtime is a surprise failure, which is far more expensive per hour.

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