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Erlang Calculator for Call Center Staffing

Model voice, chat, and asynchronous workloads with Erlang C, Erlang A, Erlang B, and Linear staffing calculations. Estimate required agents, service levels, occupancy, hourly coverage, and FTE requirements in one place.

Operating Hours

Calculator Type

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Frequently asked questions

What is the difference between Erlang C and Erlang A?

Erlang C assumes customers will wait in queue until an agent is available. Erlang A adds abandonment, which makes it more realistic when callers may hang up after waiting too long.

What service level should I target for my call center?

A common benchmark is 80% of contacts answered within 20 seconds, but the right target depends on your channel mix, customer expectations, and service cost tradeoffs.

How do I calculate shrinkage for workforce planning?

Shrinkage covers paid time agents are unavailable for contacts, including breaks, meetings, coaching, training, absence, and system downtime. Many contact centers plan for roughly 25% to 35% total shrinkage.

When should I use the Linear method instead of Erlang?

Use the Linear method for asynchronous work such as email, tickets, and back-office processing where customers are not actively waiting in a real-time queue.

Can I use this calculator for chat staffing?

Yes. For live chat, set concurrency to the number of simultaneous chats each agent can handle. Use Erlang for queued chats and Linear for asynchronous messaging workflows.