Actual Required FTE Calculation

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Wanted to get feedback on how actual required FTE is being calculated by others for inbound call volume. I'm including occupancy in Forecasted FTE Required to account for call center environment in which its not realistic that an agent can handle calls back to back.

When calculating Actual FTE required historically the model has utilized actual Occupancy in the calculation of FTE required but I believe this inaccurately inflates the requirement. However not accounting for occupancy in the requirement generates a misleading FTE # since the business would never run at 100% occupancy.


Call Centre Helper


It it is a forecast then it will be wrong. That is the nature of forecasting.

You need to start tracking forecast vs actual to see what your forecast accuracy is. You can then model it to see if there is a better value. A lot depends on averages. If you use an average occupancy figure for the year, then you may well find monthly variances, as more people take holiday during the summer and more people get ill during the winter.

Are you using Erlang calculations to work out the number of FTE required?



How do you convert workload time into hours and into seconds?

How do you calculate workload into the amount of FTEs needed?

How do you calculate FTEs?

thank you very much!



If 100 calls arrive in 30 minutes, and each call takes on average three minutes to service, then each agent can take ten calls per hour.

is the above correct, it doesn't make sense to me when I do the math.

100(calls)*180(aht)/3600 (hour) I get 5, not 10 calls per hours.

may someone clarify the above for me?

Thank you,



Same question for grossing up for planned absence/vacancy?

So basically,

1000 calls * 600 aht / 80% / 3600

= 208.33 hours

w/shrinkage of 15% (x 1.15)

= 239.58 hours

w/absents of 10% (x 1.10)

= 263.54 hours

I just want to also know if the above hours also mean the same thing as FTE requirements ,so for example 263.54 hours is approximately 263.5 FTE is that correct?

WFM Analyst

Hi Noah

100(calls)*180(aht)/3600 (hour) I get 5, not 10 calls per hours.

The result should be telling 5 FTE needed if answer in 1 hours. But you are saying "100 calls arrive in 30 minutes", then you should devide 1800 instead of 3600 then u will get answer of 10 FTE require.

Second post. 263.54 was hours not FTE. if 1 FTE production hour was 8 then you will need 263.5 / 8 hours = 32.9 FTE

*** 80% i assume as occupancy as per your formula.

Hi everyone, how com...
Hi everyone, how come we are multiplying shrinkage here? It should be base staff/hours divide by (1-shrink), right? Thanks.


Call Centre Helper

How to Calculate Shrinkage

how to detemine how many FTE i need
I need some help calculating FTE needed for an activity
Volume per month = 177,
Handle Time = 174 seconds
1 agent works 160 hours per week
28% of that time is shrinkage - therefore productive time is 115.2.
the formula I have used to determine FTE is ((Volume per month*handle time/60)/60)/(115*0.9)
The FTE number I get is 0.08, this does not seem right to me
is this correct formula to use?
any help would be appreciated


Call Centre Helper

No that is the wrong formula
You need to break the monthly volume down into days (it is not evenly spread across the month) and use an Erlang Calculator.

I also think that you mean 1 agent works 160 hours per MONTH (40 hours per week).

The answer will probably work out as between 1 and 2 FTE.

FTE required for above question
volume per month = 177
Handle time = 174 sec = 2.9 minutes

1 agent works for 160 hour per month. (5days *8hours*4 weeks)
Shrinkage = 28% = 160 of 28% = 115.2 hours is the productive hours

FTE required = ( 177*2.9)/115.2 = 4.45 FTE

FTE required = ( 177*2.9)/60/115.2 = 0.04 FTE.

As the AHT is in minutes, we need to convert it in to hours.


Call Centre Helper

This is the wrong calculation
Chandra - You have assumed that all tasks are evenly distributed across the day. This is not the case and will leave you understaffed.

You need to factor in your desired service level and use an Erlang Calculator
More details in these articles

Agree with you Jonty
yes we need to consider volume inflow pattern while deploying FTEs.I just calculated FTE required basis volume provided.

Follow-Up question
I used the Erlang's formula to get daily requirement of manpower (hourly split included).
I need to understand if I have to run 2 shifts - one 8Hr shift for 21 days and other 12 Hr shift for 15 days, how many people should i hire?
Basically, i need to extrapolate one-day requirement to a monthly requirement, considering the shifts to be arrange in a fashion where the resources get periodic offs and fit into the 2 shift structures mentioned above.
Any help would be appreciated.

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