Throughput
Throughput is the number of customers a business finishes serving in a given period, such as haircuts completed per hour or cars washed per day.
Also called: customers per hour, service rate, capacity
Throughput counts completed work, not arrivals. If a shop takes in twenty people on a Saturday morning but finishes only twelve, its throughput was twelve, and the other eight are still waiting, or have left.
It sets the ceiling on every line. When arrivals per hour exceed throughput, the queue grows, and it keeps growing until arrivals slow or someone adds capacity. That is why a shop can feel fine at 10 AM and be hopeless by noon without anything changing.
You can raise throughput by shortening the time between customers, not just by cutting the service itself. Calling the next person quickly, keeping the chair set up, and avoiding no-shows all trim the gaps. Measuring it per hour, rather than per day, shows which stretches of the day are the bottleneck.
Example
Three barbers, each averaging 30 minutes a haircut.
Each barber finishes 2 per hour, so the shop finishes 6 per hour.
If 9 people arrive in an hour, the line grows by 3 people.
Questions
How do you calculate throughput?
Divide the number of customers fully served by the time period. Three barbers who each finish two haircuts an hour serve six an hour.