What it means
The idea comes from the theory of constraints, which argues that every operation has one bottleneck that limits everything else, and that the goal is to make money faster rather than to keep every department busy. Throughput is the measure of how fast money is being generated, calculated as revenue minus totally variable costs, which in most factories means raw materials and bought-in components.
This differs from contribution margin in a way that matters. Contribution treats direct labour as variable, whereas throughput accounting argues that you pay your people whether or not the line runs, so labour belongs with the operating expenses rather than being deducted per unit.
The measure earns its keep when capacity is genuinely constrained. Once one machine, one skilled team or one approval step limits total output, the right question stops being which product has the best margin and becomes which product generates the most throughput per hour of the bottleneck.
That reframing changes decisions in ways that surprise people. A product with a lower percentage margin can be far more valuable than a high margin one if it passes through the constraint in a quarter of the time, because the business can sell four times as many of them.
Throughput is also used more loosely in operations and services to mean volume processed per period: claims settled per day, patients seen per clinic, tickets closed per week. The underlying logic is the same, since increasing the rate at the constraint increases the rate for the whole system.
In practice
Real-world examples.
Example
A contract manufacturer ranks its product lines by throughput per hour on its slowest oven rather than by gross margin. Two apparently attractive products drop down the list because they occupy the oven for three times as long as the rest.
Example
A hospital day surgery unit measures throughput as completed procedures per theatre day. Adding a second recovery bay lifts throughput by 18% without any increase in surgeon hours, because recovery had been the constraint all along.
Example
An insurance claims team stops rewarding individual case handlers for the number of files touched and starts tracking claims fully settled per week. Work in progress falls sharply and settled volume rises, because staff stop starting work they cannot finish.
Think of it
“Throughput is your production rate-how much stuff comes out of your process per unit of time.
Formula
Calculation
Throughput = Sales revenue - Totally variable costs
Throughput per constraint hour = Throughput / Hours used on the bottleneck resource
A furniture workshop sells 5,000 chairs in a month at $80 each, giving revenue of 5,000 x $80 = $400,000. The timber, fabric and fixings cost $30 per chair, so totally variable costs are 5,000 x $30 = $150,000.
Throughput is $400,000 - $150,000 = $250,000 for the month. The workshop's bottleneck is a single computer controlled cutting machine that ran for 500 hours to produce those chairs, so throughput per constraint hour is $250,000 / 500 = $500 per hour.
If a second product generated $420 of throughput per cutting hour, the chairs would be the better use of the machine even if the second product carried a higher percentage margin, because the constraint is time on that machine rather than sales value.Case study
Seen in the real world.
The following is an illustrative and entirely fictional example. Ashford Precision, an invented engineering firm, had a costing system that allocated overheads across products by labour hours and produced a margin ranking the sales team used to prioritise quotes. The top ranked product carried a 44% margin and the sales director pushed it hard.
Rebuilding the analysis on throughput told a different story in this fictional case. The star product spent nine hours on the firm's only five-axis machine, generating $310 of throughput per machine hour, while a plainer bracket with a 26% margin spent forty minutes on the same machine and generated $840 per hour.
Ashford's illustrative management reweighted the sales incentive towards throughput per machine hour and turned down two large orders for the high margin product. Revenue fell slightly over the following quarter while operating profit rose by roughly a fifth, because the constraint was finally being used on the work that paid best per hour.
Watch out
Common mistakes.
- Deducting labour and overheads when calculating throughput, which turns the measure back into an ordinary margin and loses the point of it.
- Chasing throughput on machines that are not the bottleneck, which simply builds inventory in front of the real constraint.
- Ranking products by throughput per unit rather than per constraint hour, which ignores the only resource that is actually scarce.
Questions
People also ask.
How is throughput different from revenue?
Revenue is everything customers pay you, whereas throughput deducts the costs that genuinely vary with each unit, so it measures money generated rather than money received.
Does throughput accounting replace normal financial accounts?
No, statutory accounts still require conventional costing, so throughput sits alongside them as a decision-making tool.
What if my business has no obvious bottleneck?
Then something else limits you, usually market demand, and the same logic applies with sales capacity treated as the constraint.
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