Downtime is the period during which equipment is not operational. This situation is caused by such factors as maintenance, setup for a job, broken equipment, or missing inputs, such as raw materials or qualified operators. Managers try to minimize downtime in order to maximize equipment availability, which increases the capacity of a business. However, the only downtime that really matters is for the bottleneck operation, since downtime in this area has a direct impact on the throughput of the business.

The average amount of equipment downtime is built into the practical capacity figure for a business, which is used to set the upper threshold for how much the organization can produce within a given period of time.