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What Do You Need To Estimate Agent Headcount?

What Do You Need To Estimate Agent Headcount?

Calculating the right staffing requirement of contact center agents to offer an excellent service for your customer is not an easy task. You probably have a contact center that has grown steadily agent by agent, and you might have the feeling of being under or overstaffed, or maybe your company will have a significant change in department headcount growth. You need to accurately define how many agents you will need.


Let me warn you that a simple multiplication will not be enough, and you need to look closer at your numbers to make a correct estimation. Don't worry, here we'll help you find and understand what you need to make an accurate estimation.


Erlang Calculator

Erlang C formula is a mathematical equation created by a Danish Mathematician to estimate the number of agents required in a call center. It has become a popular and helpful tool for call center managers to determine how many agents their call center need. You can find these calculators online, but you require specific information to make this estimation. Here we will explain what information you require and what you need to consider to make the best approximation to your requirements.


Volume of Calls

It's clear that to know how many agents you will need. You will have to see the number of calls you have. It can be inbound calls or outbound calls. For outbound call centers, you will need to review the number of contacts you have and your goals; your CRM will be useful for this. For inbound calls, you can get the information about the calls from your telephone system. It can tell you the number of calls per day, an hour or 30 minutes, depending on what you need.


Average Handle Time (AHT)

AHT is the amount of time an agent spends in a call. There's a debate of whether you should use this metric or not to evaluate your agents, and you can choose not to use this metric, but you need to keep track of it because you will need it to calculate the number of agents you need. An Automated Call Distribution (ACD) system or other similar systems you might have in place should give you the average AHT.

If you don't manage these metrics, reach to your QA or analytics department, they should be able to facilitate this information.


Service Level

The service level is used to see if the calls are being answered before a specific time. This metric is essential to avoid making the customers wait in line for someone to answer because this can cause call abandonment and dissatisfaction. Its expressed in a percentage and time; for example, 80% of the calls should be answered within 20 seconds.

The most used service level is 80/20, but it can be 75/35 or any other percentage and time. What you need to consider is how much the customers are willing to wait. Keep in mind that this is not the only metric that matters for customer satisfaction.

If you want to estimate your current Service Level, you need to divide the number of calls answered within the desired time by the number of calls offered; that result multiplied by 100 will give you the percentage.



Shrinkage is the paid time where the agent is not answering the phone. Things like breaks, meetings, training, vacations, holidays make up the time that the agent is getting paid but not actively working. This metric should be considered to estimate the number of agents you need. Extracting this time will give you a more accurate number.

If you don't think about this unproductive time, you might have an understaffed contact center. Generally, shrinkage is about 35%; however, do your math. Take note of all the inactive hours like absenteeism, tardiness, sick days, special projects, and all those mentioned before. Sum the shrinkage hours, divide it by the total hours available, and multiply it by 100.


Maximum Occupancy

This represents the time an agent spends on call-related activities during a specific time. It is normal and healthy for an agent to take some time between calls, and this time is needed to finish taking notes on the database or any other required activity. The average occupancy rate is between 85% to 90%. A lot of time depends on how performance-driven the agents are. Not to be confused with shrinkage, occupancy percentage doesn't consider absenteeism and lateness, for example.


Now you need to collect the information to put it in the Erlang calculator to determine the number of agents required. Please keep in mind that it will give you the number per hour of 30 minutes. With that information, you can map the numbers and see the pattern. With that, you will make a wiser decision on how many agents you need for your contact center.


Once you know the number of agents you need, the challenge will be to recruit those agents and justify the budget of getting those agents. Or you can choose to outsource, depending on the number you need. This will help you reduce cost and sometimes add extra value, like a bilingual service.


With CCSI, you can expand your operation in Mexico with bilingual & performance-driven agents. Contact us and tell us how many agents you need, and we can send you a proposal with no compromise.