What Do You Need To Estimate Agent Headcount?

Calculating the right staffing requirement of contact center agents to offer excellent service to your customers is not an easy task. You may have a contact center that has grown steadily, agent by agent, and you might have the feeling of being under- or overstaffed. Or perhaps your company is preparing for significant growth and you need to accurately define how many agents you will need.

• Erlang C Calculator
• Elements You Need to Calculate Staffing
• Putting the Numbers Together
• Expanding Your Contact Center Workforce

A simple multiplication will not be enough. You need to look more closely at your numbers to make an accurate estimation. Don't worry; here we'll help you identify and understand the information you need to estimate your contact center staffing requirements.

Erlang C Calculator

The Erlang C formula is a mathematical model based on the work of Danish mathematician A.K. Erlang. It has become a popular and useful tool for contact center managers who need to estimate the number of agents required to handle inbound call volume while meeting a desired Service Level.

You can find Erlang calculators online, but you need specific information to make the estimation useful. Here we'll explain what information you need and what you should consider when determining your staffing requirements.

Erlang C is primarily used for inbound voice operations. Contact centers with complex routing, multiple skills, or multiple communication channels may also rely on more advanced Workforce Management tools and forecasting methods.

Elements You Need to Calculate Staffing

Volume of Calls

To know how many agents you will need, you first need to understand the number of calls your contact center receives.

For inbound operations, your telephone system, Automatic Call Distribution (ACD), or Workforce Management platform should provide information about the number of calls by day, hour, or smaller intervals such as 30 minutes.

Looking at call volume by interval is important because demand can change significantly throughout the day. A contact center might appear properly staffed when looking at the total number of calls for the day while still being understaffed during peak periods.

For outbound operations, you need to consider the number of contacts available, your campaign goals, contact rates, Average Handle Time, and the productive hours available to your agents. Your CRM and contact center technology can help provide this information.

Average Handle Time (AHT)

Average Handle Time, or AHT, represents the average amount of time required to handle a customer interaction. For voice calls, it generally includes talk time, hold time, and after-call work.

There has long been debate about using AHT as an individual agent performance target because shorter calls do not necessarily mean better Customer Service. However, you still need to track AHT because it is an important part of calculating staffing requirements.

Your ACD, contact center platform, or Workforce Management system should provide historical AHT information. If you do not currently manage these metrics, your Operations, Quality Assurance, Workforce Management, or Analytics team should be able to provide the necessary data.

Service Level

Service Level measures the percentage of inbound calls answered within a defined amount of time. This metric is important because excessive waiting can contribute to call abandonment and customer dissatisfaction.

For example, an 80/20 Service Level means the objective is to answer 80% of qualifying calls within 20 seconds.

80/20 is a commonly recognized contact center example, but it does not have to be the right target for every operation. Your Service Level might be 75/30, 80/30, 90/20, or another combination depending on customer expectations, contractual requirements, call complexity, and business objectives.

Service Level should also be evaluated together with other Customer Experience metrics. For example, answering a call quickly provides limited value if the customer must call again because the issue was not resolved. This is why metrics such as First Contact Resolution should also be considered.

Shrinkage

Shrinkage is the amount of paid time during which agents are not available to handle customer interactions.

Breaks, meetings, training, coaching, vacations, holidays, absenteeism, tardiness, sick days, and special projects can all contribute to shrinkage.

This metric must be considered when estimating the number of agents you need. If you calculate that you need a certain number of agents actively handling calls, scheduling exactly that number of employees will usually leave you understaffed once unavailable time is considered.

Rather than relying on a generic percentage, calculate your own historical shrinkage. Review both scheduled and unscheduled activities that reduce agent availability and use that information when planning staffing levels.

Managing absenteeism and maintaining a stable workforce are also important parts of staffing. High turnover or unexpected absences can quickly affect your ability to meet Service Level goals, even when the original staffing calculation was accurate.

Maximum Occupancy

Occupancy represents the percentage of an agent's available time that is spent handling customer interactions and completing related work.

It is normal and healthy for agents to have some time between calls. They may need to complete notes in the database, review customer information, prepare for the next interaction, or simply have a short period between demanding conversations.

Occupancy should not be confused with shrinkage. Shrinkage represents time when an agent is unavailable to handle customer interactions, while occupancy measures how heavily agents are being utilized during the time they are available.

Occupancy levels around 85% to 90% are often used as a reference in contact center planning, but they should not be treated as a universal target. Consistently operating at very high occupancy levels can increase workload and contribute to fatigue and agent burnout.

Putting the Numbers Together

Once you have collected your call volume, Average Handle Time, Service Level target, shrinkage, and occupancy information, you can begin estimating the number of agents required.

For inbound voice operations, you can enter your call volume, AHT, and Service Level requirements into an Erlang C calculator to estimate the number of agents needed for each interval.

Keep in mind that the calculator will typically provide requirements for a specific time interval, such as 30 minutes or one hour. Map those numbers throughout the day so you can identify staffing patterns, peak periods, and opportunities to improve scheduling.

This is one of the main objectives of effective Contact Center Workforce Management: having the right number of people available at the right time while balancing Customer Experience, employee workload, and operating costs.

Expanding Your Contact Center Workforce

Once you know the number of agents you need, the next challenge is recruiting those agents and determining the budget required to support that growth.

Depending on the number of agents required, another option is to expand through a nearshore contact center in Mexico. This can provide access to a larger workforce while also offering additional benefits such as bilingual Customer Service, recruiting support, professional infrastructure, and operational flexibility.

Access to professional bilingual and bicultural agents can be particularly valuable for companies serving both English- and Spanish-speaking customers.

The physical environment and technology supporting those agents are also important. Professional contact center facilities in Mexico can provide the infrastructure and capacity companies need as their programs grow.

Whether the requirement involves Customer Service, Sales, Collections, Loan Servicing, Technical Support, or other contact center services, accurate staffing is one of the foundations of a successful operation.

Historical note: First published in 2019, this article has been reviewed and updated to reflect current contact center Workforce Management practices while preserving its core staffing factors: call volume, Average Handle Time, Service Level, shrinkage, occupancy, and Erlang-based forecasting.

Originally published: June 5, 2019
Last reviewed and updated: July 26, 2026