function calculateCallRate() {
var calls = parseFloat(document.getElementById('totalCalls').value);
var minutes = parseFloat(document.getElementById('totalTimeMins').value);
var cost = parseFloat(document.getElementById('totalOperationalCost').value);
var resultsDiv = document.getElementById('call-results');
if (isNaN(calls) || isNaN(minutes) || minutes 0) {
var costPerCall = cost / calls;
document.getElementById('resCostPerCall').innerText = "$" + costPerCall.toFixed(2);
} else {
document.getElementById('resCostPerCall').innerText = "N/A";
}
resultsDiv.style.display = 'block';
}
Understanding Call Rate in Call Center Management
In telecommunications and workforce management, the Call Rate (often referred to as the Arrival Rate) is a critical metric used to determine how many inbound contacts are entering a system over a specific duration. Mastering this calculation is the first step toward effective capacity planning and Erlang staffing models.
How to Calculate Call Arrival Rate
The standard formula for call arrival rate is simple division. To find the frequency of calls, you divide the total volume of calls by the time period in which they were received.
The Basic Formula:
Arrival Rate (λ) = Total Number of Calls / Total Time Period
Why This Metric Matters
Staffing Levels: Knowing your calls-per-hour helps determine how many agents are needed to maintain service level agreements (SLAs).
Peak Hour Analysis: Identifying fluctuations in the call rate allows managers to schedule breaks or training during low-volume periods.
Budgeting: By combining call rate with operational costs, you can derive the Cost Per Call, a vital KPI for financial health.
Calculation Examples
Scenario
Calls Received
Time Window
Resulting Call Rate
Morning Peak
300 calls
60 minutes
5.0 calls/minute (300/hour)
Afternoon Slump
120 calls
120 minutes
1.0 calls/minute (60/hour)
High Volume Event
1,500 calls
30 minutes
50.0 calls/minute (3,000/hour)
Calculating Cost Per Call
While the arrival rate tells you about volume, the Cost Per Call tells you about efficiency. To calculate this, divide your total operational expenses (wages, software, hardware, utilities) for a specific period by the number of calls handled in that same period.
If your call center costs $5,000 per day to run and you handle 1,000 calls, your cost per call is $5.00. Reducing this rate while maintaining quality is a primary goal for center managers.