Agents needed for 400 calls an hour
400 calls an hour with a five-minute handle time is 33.3 erlangs of work and needs 39 agents on the phones to answer 80 per cent within 20 seconds, at 85% 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 time | Erlangs | Agents for 80/20 | Occupancy at 80/20 | Agents for 90/60 | To schedule at 30% shrinkage |
|---|---|---|---|---|---|
| 180 s | 20.0 | 24 | 83% | 24 | 35 |
| 240 s | 26.7 | 32 | 83% | 32 | 46 |
| 300 s | 33.3 | 39 | 85% | 39 | 56 |
| 360 s | 40.0 | 46 | 87% | 46 | 66 |
| 420 s | 46.7 | 54 | 86% | 54 | 78 |
| 480 s | 53.3 | 61 | 87% | 61 | 88 |
| 600 s | 66.7 | 75 | 89% | 76 | 108 |
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.
Frequently asked questions
- Why does 400 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.
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