Free calculator
Support staffing calculator
Work out how many agents you need. For live chat it uses Erlang C, the standard queueing formula, with concurrent chats per agent. For an email queue it divides the daily workload by productive hours.
Agents online at peak
4
Agents to schedule
6
With 30% shrinkage.
Service level
96.4%
Chats answered within 60 seconds.
Average wait
7 sec
Occupancy
50%
Above 85% for long, people burn out.
| Agents | Service level | Avg. wait |
|---|---|---|
| 2 | 0% | ∞ |
| 3 | 77.8% | 1.1 min |
| 4 | 96.4% | 7 sec |
| 5 | 99.6% | 1 sec |
| 6 | 100% | 0 sec |
How the staffing math works
Live chat behaves like a phone queue: visitors arrive at random and wait if everyone is busy. Erlang C gives the probability that a visitor waits, from the traffic (chats per hour times their duration) and the number of agents. From that it follows what share are answered within your target, and how long the average wait is.
Concurrent chats are modeled as extra capacity: an agent holding three chats counts as three slots. Enter the chat duration as you measure it at that concurrency, because juggling makes every chat slower.
Email does not queue the same way, because nobody is waiting live. There the question is workload: tickets times minutes per ticket, divided by the hours an agent actually spends on tickets.
Shrinkage converts agents online into agents on the schedule. If 30% of paid time goes to breaks, meetings and absence, you need about 1.43 people on the rota for every one online.
Questions
What is a good service level for live chat?
Many teams aim for 80% of chats answered within 30 to 60 seconds. Customers on a chat expect a person within a minute; past two, many leave.
How many chats can one agent handle at once?
Two or three is common. More than that and response times inside each chat grow, so customers wait anyway, just after the first reply.
Is Erlang C accurate for chat?
It assumes nobody gives up waiting, so it slightly overstates the agents you need. That makes it a safe planning number, which is why it is the industry default.
What is shrinkage in a support team?
The share of paid time agents are not available to customers: breaks, meetings, training, sick days and holidays. 25 to 35% is typical.
More free tools for support teams
- AI support testFind out how many customer questions an AI assistant could answer from your docs.
- Cost per ticket calculatorWhat every support conversation costs you, with the breakdown.
- AI support savings calculatorWhat answering repetitive questions automatically would save.
- CSAT and NPS calculatorCustomer satisfaction and Net Promoter Score, with the margin of error.
- SLA and business hours calculatorWhen a response is due, counting only business hours and days.
- Support reply templatesReady-to-send replies for refunds, outages, app reviews and more.
Receive your first support ticket today.
Connect email or install the widget, invite your team, and start replying from one focused inbox.
- 21-day free trial
- Developer-friendly setup
- Export your data anytime