Call Centre Staffing Calculator
Enter calls, handling time, interval, answer threshold, target service level and shrinkage for one stationary period.
- Offered load (Erlangs)
- Available agents
- Scheduled headcount after shrinkage
- Service level (%)
- Probability of waiting (%)
- Average speed of answer (seconds)
- Occupancy (%)
Assumes Poisson arrivals, exponential handling times, a stationary interval and unlimited caller patience. Model estimate only; not operational staffing advice. Calculate separate periods for half-hour peaks.
A QUICK WALKTHROUGH
How to use this tool
- Enter the call volume and timing values for one interval.
- Set the target service level and unavailable-time percentage.
- Calculate the model estimate; repeat for separate peak periods.
Erlang C model
Assumes Poisson arrivals, exponential service times, stationary conditions and unlimited caller patience. It ignores abandonment, skills, routing and time-varying demand. This is a model estimate, not operational staffing advice. Calculate half-hour peaks as separate periods.
Calculation and limits
Search starts at ceil(load) + 1 and stops at 500 available agents, always with load < agents. Service level = 1 − P(wait) × exp(−(agents − load) × threshold / handling time). ASA = P(wait) × handling time / (agents − load). Occupancy = load / agents. Scheduled headcount = ceil(agents / (1 − shrinkage)). Calls: integer 1–1,000,000; handling time: 1–86,400 seconds; interval: 1–1,440 minutes; threshold: 0.01–86,400 seconds; target: 0.01–99.99%; shrinkage: 0–99%.
GOOD TO KNOW
Common questions
Does shrinkage change the queue calculation?
No. It increases scheduled headcount after calculating available agents. The result is interval headcount, not an annual FTE or shift roster.
Are my inputs uploaded?
No. All calculations use your inputs locally in the browser.