PebbleWFM

Agents needed for 5,000 calls an hour

5,000 calls an hour with a five-minute handle time is 416.7 erlangs of work and needs 429 agents on the phones to answer 80 per cent within 20 seconds, at 97% occupancy. The table runs the same Erlang C calculation across handle times and two common targets; every row opens the calculator with those inputs so you can change anything else.

Handle timeErlangsAgents for 80/20Occupancy at 80/20Agents for 90/60To schedule at 30% shrinkage
180 s 250.025997%256370
240 s 333.334497%341492
300 s 416.742997%426613
360 s 500.051497%511735
420 s 583.359997%595856
480 s 666.768497%680978
600 s 833.385498%8491220

Click a handle time to open the calculator with that row's inputs.

Assumptions

  • Calls arrive at random across a 60-minute interval; Erlang C with no abandonment.
  • Agents shown are on the phones for the whole hour. The last column divides by 0.7 and rounds up.
  • No occupancy ceiling is applied; small volumes come out under 85%, large ones above it, and the staffing requirement calculator adds the ceiling.

Change any assumption in the erlang c calculator

Frequently asked questions

Why does 5,000 calls an hour need more agents than the erlangs?
Erlangs are the average number of calls in progress. Calls bunch, so agents above that average are needed to keep queues short; the gap is the price of the service level target, and it shrinks as a share of the total at higher volumes.
Is this per hour or per day?
Per hour, for one hour that looks like this. A day has quiet and busy hours; the week planner spreads a daily or monthly total across intervals and adds the hours up.

Stop doing this one interval at a time

Pebble WFM forecasts your demand, computes the staffing requirement for every interval, builds the roster and publishes it, with self-service for agents and a copilot that can do what a planner can. Explore a sample organisation on day one.

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