Erlang C Staffing Calculator
Calculate required call center and support staffing to meet service level agreements using the Erlang C queuing formula.
Recommended Staffing
12Agents
Requires 9 raw on-queue agents (plus shrinkage allowance) to achieve 86% of calls answered within 20s.
- Traffic intensity
- 6 Erlangs
- Service level met
- 86%
- Avg speed of answer
- 11.8s
- Agent occupancy
- 66.7%
What is the Erlang C formula?
Erlang C is the mathematical formula used worldwide by call centers, customer support operations, and dispatch teams to calculate how many staff members are required to answer incoming calls within a specified Service Level Agreement (such as 80% of calls answered within 20 seconds).
The formula considers your incoming call volume, average handle time (talk time plus after-call work), and target answer speed. Adding shrinkage accounts for scheduled breaks, training, and off-queue time so your team remains properly staffed during peak intervals.
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