FREE TOOL
Erlang C call center staffing calculator
Enter your call volume and handle time to see how many agents you need on the phones — and how many to schedule once breaks and absence are counted.
Agents on the phones
11
Agents to schedule
16
Service level reached
80.9%
Average wait (ASA)
19.6 s
Calls that wait
24.5%
Occupancy
72.7%
Traffic intensity: 8.00 erlangs.
How this calculator works
Erlang C is the standard formula call centers use to plan staffing. It takes the traffic you expect — calls per hour multiplied by average handle time — and works out the chance a caller has to wait for a given number of agents. The calculator adds agents one at a time until your service level target is met.
What the results mean
- Agents on the phones — the minimum number logged in and taking calls to hit your target.
- Agents to schedule — the same number grossed up for shrinkage: breaks, training, meetings and absence.
- Occupancy — how much of their time agents spend on calls. Above roughly 85–90% for long periods tends to burn people out.
Limits
Erlang C assumes callers never hang up while waiting, so it slightly overestimates the agents you need. It is still the most widely used starting point.