How to Calculate Call Center Staffing

This is the operational version of the staffing question — the same underlying method covered from a small-business angle in our guide on how many agents your business needs, worked here with the additional factor operations teams call shrinkage.

The core formula

Required agents = (contacts in the period × average handle time) ÷ (period length × occupancy target), adjusted for shrinkage.

Shrinkage

Shrinkage is the gap between an agent's scheduled hours and the hours actually available for handling contacts — breaks, training, brief technical issues, meetings. A typical planning assumption is 15-25% shrinkage. Ignore it and your staffing plan is short by exactly that margin from day one.

Worked example — voice

A queue receives 12 calls in its peak hour, averaging 6 minutes handle time including notes. That is 72 minutes of work needed in a 60-minute window — 1.2 agents at 100% occupancy. Apply a reasonable 80% occupancy target: 1.2 ÷ 0.8 = 1.5 agents. Apply 20% shrinkage: 1.5 ÷ 0.8 = 1.9, round up to 2.

Worked example — chat

The same 72 minutes of underlying work, but chat supports roughly 2.5x concurrency per agent before quality degrades. 1.5 agents ÷ 2.5 concurrency ≈ 0.6 agents at the same occupancy and shrinkage assumptions — comfortably covered by a single agent handling chat as one part of a blended role.

Worked example — email/tickets

Asynchronous channels do not need dedicated peak-hour capacity in the same way — a ticket queue can be worked through the gaps in a voice or chat shift, provided total daily volume fits within the hours available across the team.

Recalculating over time

Staffing plans go stale. Recalculate whenever average handle time shifts meaningfully, when a new channel is added, or at minimum quarterly — volume and complexity both drift, and a plan built six months ago is a guess by the time it is still being used unchanged.

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