Machine utilization formula: how to calculate and use it

Machine utilization is the share of available time that a machine spends running and producing. The formula is run time divided by available time, multiplied by 100 to give a percentage. Run time is the hours the machine was actually producing, excluding breakdowns, waiting for work, setup and changeovers. Available time is the harder side to fix, because it can mean the hours you scheduled the machine to work or every hour on the calendar. Both are valid. They answer different questions, and the number means little until you state which one you used.

The machine utilization formula

The calculation is a single ratio:

Machine utilization (%) = (Run time ÷ Available time) × 100

Run time counts only the time the machine is making product. Stoppages for breakdowns, material shortages, operator absence, setup and changeovers come out of it. Whether planned stops such as scheduled maintenance and breaks come out of available time or out of run time is another choice to make and record. The OEE tradition removes planned stops before it measures availability, while a simple utilization figure often leaves them in.

Scheduled hours or calendar hours

Using scheduled hours as available time measures how well you run the shifts you have chosen to staff. A machine scheduled for two 8-hour shifts across five days has 80 available hours a week. Using calendar hours measures how much of the machine's total life you are using, and a week has 168 of them. Industry sources describe the same ambiguity: a figure quoted against scheduled time and one quoted against calendar time describe entirely different situations.

Take an embroidery machine that ran for 60 hours in a week. Against 80 scheduled hours, utilization is 60 ÷ 80 = 75%. Against 168 calendar hours, it is 60 ÷ 168 = 35.7%. Neither figure is wrong. The first says the shop floor loses a quarter of its staffed time to stoppages and gaps between jobs. The second says the machine sits idle for nights and weekends, so there may be room to add a shift before buying another machine.

> Tip: Write the denominator next to every utilization figure, for example "75% of scheduled hours". Without it, two managers comparing results are usually comparing different clocks.

Using the figure in practice

Use scheduled-hours utilization to find lost time inside the working day. Use calendar-hours utilization for capital decisions, such as whether a second machine is justified. Utilization also says nothing about speed or quality. A machine can run all day at half its rated speed or produce rejects, and still score well. Overall equipment effectiveness (OEE) adds performance and quality to cover that gap.

Accurate run time depends on recording when each job starts and finishes on each machine. Where that is logged against the work, such as a works order or a job, the hours can be summed per machine and fed into reporting. Decorators in garment decoration, where embroidery heads and print presses switch between short runs, often lose the most time to changeovers, so the run-time side is where they usually find the gain.