Erlang C Call Center Staffing Calculator

Free Erlang C calculator for workforce managers and team leads. Enter your call volume, average handle time, and service level target to see the minimum number of agents required — plus expected occupancy, probability of wait, and scheduled headcount after shrinkage.

Traffic & targets

Results

Traffic intensity6.67 Erlangs
Required agents10
Scheduled agents (after shrinkage)15
Achieved service level86.8%
Probability of wait17.5%
Agent occupancy66.7%

What is the Erlang C formula?

Erlang C is the standard queuing model for inbound call centers. It estimates the probability an arriving call must wait given traffic intensity (in Erlangs) and the number of agents on the phones. From that probability the calculator derives the expected service level — the share of calls answered within a target time.

How to use this calculator

Enter the forecasted calls per hour and your average handle time (talk time + after-call work). Pick a service level target — the industry standard is 80/20 (80% of calls answered within 20 seconds). Add a shrinkage percentage to account for breaks, training, and absenteeism, and the calculator returns the scheduled headcount.

Why call centers use Erlang C

Getting staffing right is the biggest lever on cost and customer experience. Under-staffing crushes service level; over-staffing wastes payroll. AgentFlow Hub tracks the live agent data — this calculator gives you the plan.