What should my service level be?

“80% in 20 seconds” is a convention, not a law. This tool finds the economically right answer instead: it adds agents one at a time and weighs the cost of each against the value of the contacts they stop from abandoning. Where total cost is lowest is your cost-optimal staffing — and the service level that comes with it.

Contacts / interval

AHT (seconds)

Interval (minutes)

Avg patience (seconds)

Loaded cost per agent-hour (£)

Value of an abandoned contact (£)

Lost revenue, callback cost or goodwill.

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Labour cost Cost of abandons Total cost Cheapest point

Why this beats copying 80/20

Every extra agent costs a near-fixed amount and buys a falling number of saved contacts — so there’s a staffing level where the next agent costs more than the abandons they’d prevent. That’s the economic optimum, and the service level it produces is the one that actually fits your contact value and cost base, not someone else’s convention. Cheap contacts and expensive agents push the optimum toward a lower service level; valuable contacts and cheap agents push it higher. The famous “80/20” is just one point on this curve — sometimes the right one, often not.

Maths: Erlang A (abandonment), the same engine behind the Erlang A calculator. It’s the cost side of the decision — brand promises, contractual SLAs and customer expectation can justify staffing above the pure optimum. Use this to know what that choice is costing you.