FTE Calculation Question

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I have seen FTE hours requirements calculated two different ways when factoring in an 80% occupancy.

Grossing up by 20%

1)((NCO x AHT)/3600) x (1+(1-OCC))

Dividing by 80%

2)(NCO x AHT)/OCC/3600

Using 1000 calls, 600 AHT and 80% OCC, the first equation equals 199.99 hrs.

The second equation equals 208.33 hrs.

Which should I be using?


Call Centre Helper

It looks like you have the classic problem of adding and subtracting 20%.

If you add 20% to 80 you don't get 100% - you get 96%.

But if you take 20% of 100 away you get to 80%.

Occupancy is always worked out as a percentage of total time.

So Total time * Occupancy (as percentage) = (NCO * AHT)

Where NCO = Number of calls offered

and AHT = Average Handling Time. You then just need to make sure that they are both in the same unit of time.

Number 2 is the correct answer.

Thanks for getting back to me;

So taking this one step further, because offphone shrinkage like break/lunch/coaching/training is not part of the call handling time, am I ok to use the gross up method, and just multipy by 1.15 if i want to increase my required hours by 15%?

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

Or should I be dividing by 85% for shrinkage and 90% for absence?

Thanks for the clarification.


Call Centre Helper

You always work down from the total amount of time. i.e. 3600 seconds in the hour. 15% shrinkage is 540 seconds. 10% absense is 360 seconds.


100% of available time

- 15% Shrinkage

- 10% Absenteesism

- 20% Idle time

- 10% Wrap Time

- 45% Talk time

= 0

It's much easier to visualise it if you plot it on a pie chart. This way it always adds up to 100%.

Please note that absence is normally included in shrinkage. The formula for shrinkage is (planned leave + unplanned leave + away from post)/roster for the day



I have two questions abotu FTE calculations and call capacity

1. If your data is as such

FTE 740

FTE hours/month 168

Load factor: 25%

Expected occupancy 70%

expected AHT 350

How many calls can the above call centre take with those metrics?

what would be the proper calculations because i see more then one somtimes

second question

Call Volume/Month: 345,000

Abandon Rate: 5%

AHT: 348

Expected Occupancy: 55%

Load Factor: 30%

FTE Hours/Month: 170

How many FTE would you need to do the above job and what would be the proper calculation?

Sr Executive WFM


740*168 = 124320

After Occ = 124320*70% = 87024

Less Shrinkage = 87024*(1-25%) = 65268

One Call Time = 350/60 = 5.83 Minutes

Probable # in one Hour = 10.29

# of calls answerable = 65268*10.29 = 671328

By the way, your shrinkage and Occ are both raising enormous cost to you though it entirely depends on your project's operational requirement. If you can manage, keep them Occ = 80%, Shrkg = 20%

Leaving your second question because turning around this answer delivers your second objective.



thank you very much,

another question if you have SVL of 93% , 66% and 72% and you wanted to get the weighted average how do you do this if you have no information of calls offered or answered, all you have is SVL. Can you still get a weighted average of those SVLs?

Sr Executive WFM


Weighted Avg % is actually the sumproduct of those numbers and percentage which is the case here. So you will have to know the numericals of offered/answered calls as far I know.



thats right because SVL=calls offered divided by sum calls offered.

Also another question with respect to the third post up. If i wanted to find cost per call and the cost that the company was paying was 25 dollars per productive hour, i would just take the Probable # in one Hour = 10.29 and then take the 10.29 and multiply it by 25 dollars is that correct?






I have a Question why do some use this equation(NCO x AHT)/OCC/3600 to find workload hours? when at times i see it being used to find how many calls the agents can take iam a little confused, for example some say if call centre takes 100 calls in 30 miniutes and each call takes 3 min or 180 seconds how many calls would these reps take, i would say 10. May you please clarify this for me?



Is wrap time and absence both a part of shrinkage?

also idle time 20% iam guessing this is occupancy which usually may be 80% so that leaves 20% idle time correct?

Heloo...i have fte hours per week, shrinkage,attrition, % competent, occupancy, headcount and interval staffing...how to calculate fte per week

Annual BAU Attrition 65%

FTE Hours per Week: 40

Shrinkage: 25%

Occupancy: 90%

Headcount Campaign 1 76

% Competent 65%

Handled calls by each rep
if you have 100 calls in 30 min then 1800 sec so agents required will be 10 reps handling 10 calls each

100*180=TT 18000/1800=10 resp and 100/10 = 10 calls each

FTE required
Annual BAU Attrition 65%
FTE Hours per Week: 40
Shrinkage: 25%
Occupancy: 90%
Headcount Campaign 1 76
% Competent 65%

On what basis do you wwant to calculate the FTE ? It should be on basis of contacts received in Week or month

How to do calculation to Find out Headcount require
Hi, Below are figures and I am unable to find how many HC require to answer 10000 calls at the AHT of 150 seconds with occupancy of 85%. Also please add Shrinkage on the same as 15%

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