Contact Center Staffing Calculator
Dividing total call minutes by 60 always understaffs a support desk because customer calls arrive in random clusters, not in a neat single-file line. This calculator uses the industry-standard Erlang C queueing model to determine how many active seats and total rostered agents you need to hit your target service level without burning out your team.
Workload & Service Targets
Enter your call arrival volume, handle time, and SLA goal.
Include talk time, hold time, and after-call wrap-up notes (for example, 3.5 minutes is 210 seconds).
Industry standard is 80%.
Commonly 20 seconds (80/20 SLA).
Accounts for breaks, training, coaching, leave, and unplanned absence (typically 25% to 35%).
Staffing Recommendation
Erlang C steady-state queue calculation.
Requires 14 active agents logged in at their desks to handle 10.5 Erlangs of traffic intensity.
Headcount Sensitivity Table
| Active Agents | With Shrinkage | Service Level | Avg Wait (ASA) | Occupancy |
|---|
How the Erlang C staffing model works
Developed by Danish mathematician A.K. Erlang to model telephone exchange queues, the Erlang C formula calculates the probability that an arriving caller finds all agents busy and must wait in line. First, it converts call volume and average handle time into Traffic Intensity (Erlangs), where 1 Erlang equals one full hour of call workload per hour. Next, it uses Poisson arrival probabilities to compute the exact queue wait distribution for a given number of seats, finding the smallest agent count that satisfies both your target service level and your maximum occupancy threshold.
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