Answers: What is the Minimum Number of Staff Required for a 24/7 Call Centre?

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Do you get confused when calculating how many staff you need in a call centre that is open 24 7 (24/7)?

Below, we answer a question on staffing a callcentre open 24 hours a day, seven days a week, with helpful advice from our readers.


What is the minimum number of staff required for a 24-hour call centre with 2 staff per shift and what should the ideal hours be like (based on a 40-hour work week)? E.g. 7am-4pm, 3pm-12midnight, 11pm-8am, etc.

How Many Employees do I Need to Cover 24/7

The answer to how to staff a 24 7 call centre operation  is complex, and therefore the question of the minimum number of staff needed for a call centre is not straightforward.  Here pose a couple of solutions.

Graph describing the equipment people use to schedule WFM. 9.1% pen and paper, 59.1% spreadsheets, 28.8% on premise WFm, 16.8% Hosted WFM/

Most call centres are using spreadsheets to schedule the staff in their contact centre.

Workforce management (WFM) can be used to schedule the staff into the call centre. A WFM software can be used to determine the staffing of the call centre, with the ability to factor in shift schedules and patterns, as well as the channels in which the calls are being managed.

However, should you want a more hands on approach, as 68.2% of companies do, use of a formula or spreadsheet may be better suited.

A basic schedule can be created with the reliance upon formulas, such as the Erlang C formula, which will provide a minimum answer. The Erlang C formula takes into consideration the number of calls, call reporting, call duration, service level and target answer times to give the number of agents.
The Erlang C formula can be worked out manually, we have worked example which takes you through the steps, or with the use of an Erlang calculator.

There is both an online calculator and spreadsheet version of the Erlang calculator.

Using the Online Staffing Calculator

We have a version of the Erlang Calculator, which figures the number of staff needed to reach an agreed service level. When you change the values of the parameters, it becomes a 24 hr staffing calculator.

A screenshot of the Erlang staffing calculator, with the drop down being changed to 24 hours.

The Call Centre Erlang Staffing Calculator showing a capacity for 24 hours.

This gives an output of the number of agents you will need for the 24 hours, as well a graph of the distribution of calls across the period.

Click here to go to the Online Erlang Calculator for Call Centre Staffing.

The results output of the Erlang Calculator, with the maximum number of agents and the average number of agents for the number of calls per hour and day.

This is an example output of the Erlang Calculator, with a graphic of the maximum and average agents and a graph of the distribution of the calls across 24 hours.

To calculate the number of agents you will need across a 24 hour period, enter your own data into our staffing calculator

What FTE Should be Used to Cover 24/7?

You can use the Erlang calculator to work out the full time equivalent (FTE), which is the equivalent headcount to one person working full time.  From the FTE, the staff numbers can be calculated.

We have received some recommendations of FTE from our readers.


The absolute bare minimum would be 4.2 FTE on paper, if you wanted to stick to no more than 40 hours per agent per week.

24×7 = 168 hours per week to be covered.

168/40 = 4.2 FTE

However, you need to bear in mind that with five members of staff, it only leaves 32 hours per week available for vacation or sick coverage. This may seem narrow, but it can be done.

Thanks to Chris.


It always used to be 5.4 FTE, as a rule of thumb, to staff one position for 24/7.  Therefore, this equates to 11 agents for two 24/7 positions. Whilst this allows for holiday and sickness cover, it doesn’t easily cover break periods.

Thanks to Jonty .

Follow the link for further information for a step by step approach to figuring out how to staff your call centre: How to Work Out How Many Staff You Need in a Contact Centre

The Shift Hours and Patterns Used in Contact Centres

The length and number of shifts is unique to your call centre. There is no definitive answer. However, we do have some pointers for you to consider. Usually shifts range between 8 hours and 12 hours. There are a number of shift patterns you could adopt, including fixed shift, flexi-time, annualised hours and rotating shifts. Ideally, your choice of shift pattern would minimise absence and maximise productivity

As many of our readers have hands on experience with organisation of shifts, we turn to them for their helpful advice.


Many companies run eight-hour shifts running from 8 am till 4pm, 4pm till midnight and midnight till 8 am.

For a minimum number of staff, you could use 12 hour shifts

Thanks to Kirsty.  


For a minimum number of staff, you could use 12 hour shifts. This would give you four shifts, with only four people needed to cover the 24 hour period. For an 8 hour shift you will need a minimum of six shifts, and six workers.

Thanks to Rob. 


The first question is how busy your call centre is going to be. If it is going to busy, for example, if every agent receives a call after two minutes, then you will need 40 Agents to the following shifts: 7am till 4pm, 8am to 7pm or 9 am to 6pm. For the nightshift, you can have 15 – 20 Agents and schedule them accordingly. All in all, you will need 60 Agents.

Thanks to Filita Macdonald.


I’ve seen that regardless of shift length, the productivity of the agent drops off after six hours.

With personal experience of both ten hour and eight hour shifts, I’ve seen that regardless of shift length, the productivity of the agent drops off after six hours.  So I would rather pay for two hours of non- productivity rather than four! Eight-hour shifts allows for more concentrated work to be done during the day.

Thanks to Louise. 

For me, it is simplest to have two shifts a day, with 14 in total for the week. Each week, a staff member covers 3 shifts. This roughly equivalates to five members of staff needed to cover these 14 shifts.

Thanks to Nel.


At our work place, our agents work an 8 hour shift with a paid half hour for lunch. This allows us to break the 24 hours into 8 hour shifts, 8 am to 4pm, 4pm to 12am and 12am to 8am.

Thanks to Bob Hannon.

For further information about different shift patterns, look at our article on the best shift patterns for call centres: The Best Shift Patterns for the Contact Centre

Have you any experience of staffing a call centre 24 hours a day, 7 days a week? We would love to hear your thoughts in the comments section below.

Published On: 20th Aug 2008 - Last modified: 19th Nov 2021
Read more about - Workforce Planning, , ,

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  1. The minimum number should not be less than 15 and should not exceed more than 50,as its just 2 staff people available.

    If less than 15 the cost to run would increase and if more than 50 no profit would be gained.

    navdeep kashyap 28 Aug at 9:40 pm
  2. it depends on call volumes and after call/admin work.

    Ben 30 Oct at 12:36 pm
  3. Have you ever heard of Erlang calculator? This works out the FTE needed by the volume of expected calls, target service level, average call lenght, speed to answer and target abandoned rate. Erlang will give you the minimum number needed to achieved this. the only requirement is an understanding; historical or forecast of expected call volumes.

    Beverley Cragie 30 Oct at 4:23 pm
  4. Is there any research regarding the 4 day 10 hour work week for call center employees the work by regions?

    Angie Blair 6 Dec at 7:27 pm
  5. I would like to check on what is the minimum number of staff required for a 19-hour call centre with 20 staff per shift for 8 hrs and 12 staff per shift of 11 hrs?

    Also, how do we plan for/handle scheduled annual leaves and unplanned sick leave or urgent leave?

    sai 14 Jun at 3:12 pm
  6. I agree with Ben, it depends.

    Hubi 24 Aug at 9:27 pm
  7. Hi there,

    Is there any formula to find the manpower requirement for 3 Shift duty roster for (8+1[Break]) Hour duty, (8+1[Break]+1[OT]) Hour duty and (8+1[Break]+2[OT]) Hour Duty. Please reply.

    and finally how to make their rost Plan in Excel Chart with formula.

    Omar Sharif 16 Jan at 2:41 am
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