Watch theline grow.
Queue Wait Time Calculator: How Many Staff Do You Need at Peak?
Set your busiest hour. The counter shows the average line, and the receipt shows how long people wait and what one more person serving would change.
How it works
The calculator uses the standard Erlang C queueing model, which assumes customers arrive at random and are served in turn by any free staff member. It is widely used to plan call centres and counters.
If utilization reaches 100%, the line grows without limit
Waits rise slowly at first, then sharply as utilization passes about 80–85%. That is why adding one person at the bottleneck often cuts the wait dramatically. Read bottlenecks and Little’s Law for the full lesson.
Common questions
How many staff do I need at peak?
Enough to keep utilization comfortably below 100%, usually around 70–85% for steady waits. Use the calculator with your real peak arrivals and service time, then add a person if the wait is longer than customers will tolerate.
What is Erlang C?
A queueing formula that estimates the chance a customer has to wait and the average wait, given random arrivals, a service time and a number of servers.