Call Center Workforce Management 101


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We often get questions about different aspects of workforce management (WFM). “How do we make sure we have the right number of agents available to take calls?” We know that our center cannot be overstaffed or we run the risk of having a lot of agents doing absolutely nothing. At the same time, we also do not want to burn out agents by keeping their occupancy level too high. In order to find that staffing sweet spot, we have to start by listening to the customers.

Earlier this fall, we were at a meeting with some other colleagues at the NICE inContact headquarters in Salt Lake City.  While there, we were able to talk about different policies and procedures that come into play for each of us. Our use of analytic tools that show how sentiment scores correlate to hold time’s effect on customers became a topic of discussion.

There was agreement that we can learn what our service level should be based on the customer’s sentiment.  At what point do they start to get irritated while on hold? The answers will vary based on your customers. Your WFM team needs to know just how much your customers can withstand in order to find that optimal number. This is just one of the rolls for WFM.

For everyone who is looking for how to improve your staffing efficiency, this blog is for you!! As a floor supervisor, or middle management team member, that is on the call center floor daily, you have probably learned how to do almost everything in your center. If you are left wondering how the WFM team does their job in finding the optimal number of agents for efficiency, we hope this helps explain one process that can be used to get there.

Really, how do they know what staffing numbers are needed?  On our Expivia website, we just launched our staffing calculator.  It’s a free tool for you to use.  It is really helpful because it knows how to calculate staffing needs for you, while also being pretty easy to use, too.  Hopefully, these tips will make workforce management a little bit easier for you to understand.

Our calculator is not just a magical tool that we came up with; it’s basically an Erlang-C calculator. It uses your own statistics to create a formula that takes into account your KPIs, business use cases, and what you are trying to compute.  Then it will spit out the number that will get you to your goal.

If we break this down a little more, you will see that this method is pretty simple and also pretty effective. You don’t need to go number crazy and gather a whole bunch of new data to figure these things out. Instead, you will use statistics you should already have to fill in the blanks with the requested variables.  You will need to know your handle time, service level, shrinkage, and answer time. Then, as long as you know your historical staffing level by interval (in most cases by the hour), the calculator will help you correlate how to get to those magic optimal staffing numbers.

Calls per interval

This will be historical data. How many calls do you get per hour? If your center opens to callers at 8 AM and closes at 9 PM, every call during those hours needs to be tallied. The number of callers needs to be counted and marked daily. You will want to compare multiple dates of data to be sure you are seeing the whole picture.

Handle time

What is your overall handle time? Once your call hits the queue, how much time elapses until the agent dispositions the call? This information is probably already being tracked in other metrics. You cannot plan for staffing if you do not also know the average handle time for each client.

Answer time & Service level

The industry average for service level and answer time is 80/30.  This means 80% of the calls are answered in 30 seconds or less.  Some call centers are much more stringent; some are much more relaxed. It’s up to the culture of your organization to know how quickly your calls need to be answered.


This percentage is about more than just the number of call-offs that are missing work at one time.  There is external shrinkage which is your PTO, call-offs, and people who leave early for whatever reason. But, then you also have to look at internal shrinkage, which is when your staff is present but taking a break, playing a game, or being coached off the floor.  Your organization’s culture defines your shrinkage, too.  If you have reps off the phone more, that will be a factor in your workforce management.

In our calculator, there are boxes for several data points that you will need to fill in such as your average handle and answer time. You will add in your shrinkage numbers; our average is around 15%, but it could vary from 10-25% depending on your center’s culture.

When calculating shrinkage, it’s pretty straight forward. You add the total internal shrinkage hours to the total external shrinkage hours.  Divide those hours by the total hours available and then multiply by 100 to get your percentage. Most of our programs are between 10-15%. Don’t forget that when your shrinkage percentage fluctuates, it will make your required staff fluctuate as well. If your shrinkage percentage is accurate you won’t need to use other metrics like occupancy to calculate for WFM. 

After completing those data points, fill in your average call number intervals using the historical data you have been collecting. If you haven’t been tracking this, doing so is fairly simple. Create a spreadsheet with columns for every hour your center is open and fill the cells with the number of calls you receive each hour.  Continue to add rows to the sheet for multiple days to get a wide range of data. Compute the average for each hour and add it to the staffing calculator. Once that information has been added, the calculator will tell you how many agents you need working during every interval.

When plugging your service level into the calculator, you could also play a little bit by putting in different service levels that come into play at different times of the year. If you know that you get a lot of calls from December until February but far fewer calls from April until July, use that data when planning for staffing for those time periods.  For most organizations, having the same number of agents available at all times is just not good business sense. Your staff needs to ebb and flow with your historical call numbers.

Workforce management is key to finding and forecasting the best staffing levels for your call center and your clients. Workforce management for larger 200+ seat call centers can get really complex. If your center has that many agents, you might be best served by using a tool similar to the one from NICE InContact that we use at Expivia.  However, if you are a smaller shop, our calculator should be really beneficial.

The use of a call center staffing calculator like ours will help smaller organizations find these numbers without spending a lot of money on a program to do it.  We’re not collecting your data if you use ours. You don’t even have to use ours–find something that works for you. We just like to share information and be a helpful resource to others.

Want more call center operations content? Head over to our weekly call center operations podcast “Advice from a Call Center Geek!” at

Advice from a Call Center Geek is a weekly podcast with a focus on all things call center and contact center. We discuss topics such as call center operations, hiring, culture, technology, and training and have fun doing it! #callcenter #contactcenter #CX #custserv #callcentergeek

Thomas Laird
Founder and CEO of award-winning Expivia Interaction Marketing Group. Expivia is a USA BPO omnichannel contact center located in Pennsylvania. I have 25 years of experience in all facets of contact center operations. I have the honor of being a member of the NICE inContact ICVC Board. The iCVC is a select group of inContact customers selected to join as trusted advisors to help InContact validate ideas for new products and features and plans for future innovations. I am also the author of "Advice from a Call Center Geek" and host of the podcast of the same name.


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