Throughput is the rate at which a process delivers finished units — output divided by the time taken. It is the reciprocal of cycle time and the number operations managers care about most, because it is what converts directly into revenue. A process with a two-minute cycle time has a throughput of thirty units an hour, and the two statements are interchangeable.
Throughput measured on total output overstates what the business can actually sell, because some of those units are scrap or need rework. Good throughput, output multiplied by yield, is the figure that matters commercially. The gap between the two is where quality problems turn into capacity problems: a process running at 96% yield is effectively giving up 4% of its capacity before anything else goes wrong.
Little’s Law connects throughput to inventory: work in progress equals throughput multiplied by flow time. Rearranged, flow time is work in progress divided by throughput, so a queue of 340 units at 27.50 units an hour takes 12.4 hours to clear. The law holds for any stable process regardless of how the work is sequenced, which makes it one of the few genuinely universal results in operations.
The formula
Units- Units completed in the period
Hours- Hours the process ran
WIP- Units currently in progress in the system
Yield- Share of output that is good first time
How to use this calculator
- Enter units produced and the hours taken to produce them.
- Enter the work in progress currently in the system.
- Enter the first-pass yield so good throughput can be separated from gross output.
- The gauge shows units per hour; flow time and period output follow below.
Worked examples
4,180 units in 152 hours
Throughput is 27.50 units an hour, a cycle time of 2.18 minutes. At 96.5% yield only 26.54 of those units an hour are good, so 0.96 units an hour are lost capacity.
Little’s Law on the queue
340 units of work in progress at 27.50 an hour means a flow time of 12.4 hours. Halving the work in progress to 170 would halve the flow time to 6.2 hours without changing throughput at all — which is the entire argument for limiting WIP.
How to read your score
Frequently asked questions
What is the difference between throughput and capacity?
Capacity is the maximum possible rate; throughput is the rate actually achieved. The gap is made up of downtime, slow running, changeovers and quality losses, which is what OEE decomposes.
What is Little’s Law?
Work in progress equals throughput multiplied by flow time. It holds for any stable system regardless of sequencing, which is why reducing WIP shortens lead times without needing any process change.
Should throughput be measured on good units only?
For commercial purposes, yes. Scrap consumes capacity but produces nothing sellable, so gross throughput overstates what the process delivers. Report both and the gap is your quality cost in capacity terms.
How do I raise throughput?
Only by relieving the bottleneck. Improvements anywhere else add work in progress without adding output — the most reliable rule in operations and the most consistently ignored.
Throughput reference
| Units produced | 40 hours | 80 hours | 152 hours | 300 hours | 600 hours |
|---|---|---|---|---|---|
| 500 units | 12.5 | 6.2 | 3.3 | 1.7 | 0.8 |
| 1500 units | 37.5 | 18.8 | 9.9 | 5.0 | 2.5 |
| 4180 units | 104.5 | 52.2 | 27.5 | 13.9 | 7.0 |
| 9000 units | 225.0 | 112.5 | 59.2 | 30.0 | 15.0 |
| 20000 units | 500.0 | 250.0 | 131.6 | 66.7 | 33.3 |
Divide sixty by any cell to get the equivalent cycle time in minutes.
| Work in progress | Flow time (hours) | Flow time (shifts) | Good units cleared at 96.5% |
|---|---|---|---|
| 50 | 1.8 | 0.23 | 48 |
| 120 | 4.4 | 0.55 | 116 |
| 340 | 12.4 | 1.55 | 328 |
| 700 | 25.5 | 3.18 | 676 |
| 1,500 | 54.5 | 6.82 | 1,448 |
Little’s Law: flow time is work in progress divided by throughput. Throughput is unchanged by the size of the queue.