Erlang C Calculator for Contact Center Staffing
Stop guessing at staffing levels. Use this free Erlang C calculator to instantly determine how many agents you need to answer your calls and hit your service level goals.
Free Erlang C Calculator
Enter your call center’s metrics to find your “sweet spot” for staffing.
Erlang C Calculator
What is the Erlang C Calculator?
Erlang C is a mathematical formula that is the foundation of contact center workforce management (WFM). It was created by Danish mathematician Agner Krarup Erlang to model call traffic.
In simple terms, the formula helps you balance three competing factors:
Customer Demand
(Calls per hour)
Your Resources
(Number of agents)
Your Goal
(Your Service Level, e.g., "Answer 80% of calls in 20 seconds")
By using this calculator, you can instantly find the “sweet spot” for staffing, ensuring you have just enough agents to keep customers happy without overstaffing and wasting money.
Why Is This Calculator Important?
For CXOs, Ops Managers, and WFM Analysts, balancing costs and service is the single biggest challenge. This tool helps you solve it.
The Problem
Overstaffing & High Labor Costs
Understaffing & Poor Service
Wasting Time in Excel
The Solution with This Calculator
Stop guessing at staffing. This tool finds the exact number of agents you need, helping you reduce labor costs.
Automated tracking of actual vs. scheduled hours with instant alerts.
Smart shift coverage suggestions and automated agent notifications.
The Limitations of Erlang C (And What to Do About It)
This Erlang C calculator is a powerful planning tool. But in a real contact center, your plan is obsolete the moment the day begins.
Erlang C was invented in 1917. It’s a fantastic starting point, but it cannot account for modern contact center problems:
It Can't See Shrinkage
Your plan calls for 10 agents, but what happens when 1 is late, 1 calls in sick, and 2 take long breaks? Your plan is broken.
It's Not Real-Time
Your plan is based on history. It can't react when call volume suddenly spikes right now.
It's for Phones Only
Erlang C doesn't work for multi-channel operations. It can't calculate your staffing for chat, email, and social media.
It Can't Manage Adherence
The calculator assumes 10 agents are logged in and ready for 60 minutes. It can't tell you if 3 of them are actually idle or in a non-productive app.
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Frequently Asked Questions
AHT is the total average time an agent spends on an interaction. This includes the customer’s talk/chat time plus any “wrap-up” time the agent spends on the case after the customer is gone.
This is your contact center’s primary goal. It’s a promise, written as “X% of calls answered in Y seconds.” The most common SLA is 80/20 (80% of calls answered in 20 seconds).
This is the percentage of time an agent is busy with call-related work (talking or in wrap-up) versus waiting for a call. High occupancy (e.g., 95%+) is dangerous and leads to agent burnout. A healthy rate is typically 80-90%.
Erlang C is for Planning. HiveDesk is for Reality.
You’ve calculated your plan. Now, you need a platform to manage what’s actually happening.
HiveDesk’s WFM platform is your real-time command center. It goes beyond Erlang C to give you:
Real-Time Adherence
See who is actually on schedule, late, or on a long break, right now.
Automated Scheduling
Build perfect, optimized schedules in minutes.
Live Dashboards
See your actual service levels and queue stats, not just a forecast.
Shrinkage & Monitoring
Automatically track shrinkage, compliance, and agent productivity.
Don’t just plan your day. Win it