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What factors would you consider while calculating Shrinkage for an Inbound Campaign.



Shrinkage for Inbound Call Center
Shrinkage in a broad term means every activity that would keep an agent off the phone... this would include his/her leaves & holidays entitlement, offline activities (training, meeting, coaching..etc), breaks, outbound calling (if any)... and once you have gathered all the information above, you calculate the total time for the activities above against the annual working days...

One example...
Number of weeks in an year - 52
Working days per week - 5
Total Working Days in an year - 260 (2340 Hrs at 9 Hrs per day of shift length)

Leave+Holiday Entitlement/year/agent - 38 (342 Hrs) which is 14.62% of 2340 Hrs
Once you subtract the 38 leave/holidays from 260 working days, we get 222 actual working days. If an agent takes a break of 1 hr everyday, then he/she would end up utilizing 222 Hrs of break in an year... which is 11.11% of (260-38) *9 Hrs = 1998 Hrs...
Similarly, if there is a client specified offline time, then calculate it as a percentage against 1998 Hrs....similarly, any misc. time (example, bio breaks etc) can be calculated as an additional shrinkage % age against 1998 Hrs...
Outbound Calling as a %age against 1998 Hrs.....

Wen u total up all these %ages....that gives you the shrinkage for your inbound center... On many occasions Ops would come back to you and ask you whether you have factored absenteeism as a shrinkage... the rebuttal for that is that on how many occasions is a person who was absent the previous day is actually marked as absent in HR Payroll and his salary is rarely happens in an Indian BPO the end of the payroll cycle...all Team Leads mark their agents who were absent on any specific day as either EL (Earned Leave) or a SL (Sick Leave).... therefore in the end, they end up utilising the leave balance allocated to every agent...hence the leave entitlement is already factored in the Shrinkage Calculation....

Hope this helps....



Hi Piyush
That was some very good information u wrote in. Do u even calculate staffing numbers to cater to x number of call, given the service levels and AHT etc

Do let me know, have some questions there



Hi Thomas
Yes, I do calculate staffing numbers basis the x number of calls at y aht to meet z% SL... Do share your query with me and I will try my best to provide you with the best possible solution....

Business Analyst

BGL Group

Whilst on the subject of Shrinkage, does anyone have a method of adding seasonality into the equation rather than flat-lined (30-35ish%) throughout the year?

Currently we do no better than estimate this based on our forecast monthly workload, then work out as a % of forecast FTE...

Resource Analyst

ANON VoicebasedServiceCentre

Seasonal Shrinkage
Seasonal shrinkage sounds interesting :)

Piyush - appreciate the fact that you cared to detail out the shrinkage factors ... liked the part about unplanned absence already being factored in the shrinkage as per leave entitlement of the year.

Seasonal shrinkage is very much a fact .. but most of us prefer to ignore it. We are too focussed on calls, AHT, ASA ... we miss out factors as important as shrinkage.

Jon - may be helpful to start keeping a track of shrinage per month/fortnight & it will be handy a year down the line. (this would be the planned leave applications)

For unplanned leave (sick leaves / casual leaves) i do not suspect any possibility of seasonality ... but definitely you will find trends, Best option in case of unplanned leave would be to take unplanned shrinkage as per recent weeks.




Seasonal Shrinkage is achievable....
If you are doing a RFP bidding for a new contract and want to know what shrinkage needs to be applied to arrive at a fte count for the process to begin, then at that stage the shrinkage figure would be a flat value... However, when doing the resource model for a process, and trying to calculate the fte required with respect to the locked forecast volume, then the seasonal shrinkage could easily be applied basis the previous trends... ideally, if the process is closed on a bank holiday and we are already aware of the dates when there is a bank holiday, we may not need to factor the bank holiday shrinkage at all...

The leave entitlement trend can also be populated basis the previous year actuals or basis the understanding that most of the leaves occur during the holiday season, therefore the shrinkage during those months would be higher than compared to rest of the months/weeks, whereas the average of all the 52 weeks would give us the same shrinkage %age which must have been calculated earlier...

Similarly, the shrinkage %age factors in any client approved training. In case if this information could be shared before hand, then the shrinkage %age could be hiked up in the weeks when the training needs to be done and could be lowered in the remaining weeks.

The planning around unplanned absenteeism can have a trend/pattern...ideally, in my experience in WFM, If the campaign is closed on the weekend (5 days working only)...then the unplanned absenteeism is usually high on a Friday or a Monday... All of a sudden, the Ops starts getting calls from their team members that they are not well or they have some urgent work...(on a lighter note) the best thing to notice is that the agents are able to time their sickness just hours before the weekend....or just to enjoy the long weekend, they may call in sick on Monday too...
If the shrinkage was planned on a daywise basis, then this trend ould have actually helped, however on a weekly usually levels up...unless there was a mass unplanned absenteeism which took place in a particular week which threw everything out of proportions....

Hope that helps....



Hi Piyush,

Sorry cld not reply earlier. Besides using Erlang and other excel operations, if someone had to ask me hw many staff are required to man inbound calls, with an SL of 85% , AHT of 5 mins and x number of calls hitting per would i go about calculating that?

I know we can just input these figures on excel cells and get the required input, however i wanted to know how the math is it something to complicated to decipher? Would really appreciate if you could throw some light here.

Business Analyst

BGL Group

Seasonal Shrinkage
Hi Piyush,

Thanks for your opinion.

I agree that in order to finely tweak our shrinkage throughout the year rather than flatline we need to look at previous months'/years' trends.

The challenge we have is this: Say our FC Workload peaks in Aug and troughs in Dec. Ideally we'd want to allow higher shrinkage in Dec (more holiday, training, meetings, etc), and lower shrinkage in Aug (less holiday, training, meetings, etc).

If we then look at our ACTUAL trends over the last couple of years, we find an opposite pattern to this, ie, high sickness levels in Aug with everyone wanting to take their summer holidays; and less people wanting to book holiday in Dec as they're trying to carry over to the following year.

At the moment our process of matching seasonal shrinkage with FC Workload goes against our actual trends and we feel caught in the middle of "planning vs operational" targets.




Is the scenario you give based on actual events? Depending on the service you deliver to your customers you will have seasonal peaks/troughs and these are likely to alter only in respect of volume rather than shape. What is it that is driving your seasonlity change? (If it's not a hypothetical scenario of course)



Hi Dickens,

You can just input these figures on excel cells and get the desired output, but it would not be accurate. Forexample if you have 30 min interval with x number of calls coming in and an AHT of y secs. You would not in a position to estimate what amt of calls would land together in that interval without Erlang.


You have 10 calls forecasted to come in an interval with an AHT of 300 sec. Without Erlang you would not be able to calculate what is the probability of all those 10 calls coming in together and how many staff you would need to staff to answer those calls in service level.

You would end up either understaffing or overstaffing in that interval as it would then be simple work load calculation of 10 calls at 300 sec is 3000 sec. The SL is 85% so 85% of 3000 is 2250 seconds or 8.25 calls. To staff for this we need 2500/1800 that is 1.41 FTE for the interval.

But what happens if 5 calls come in simultainously, the SL goes for a toss. Erlang uses the trunk capacity to arrive the highest probability of max calls arriving together and then suggests a staffing requirement.

Business Analyst

BGL Group

Thank you Steve,

The scenario mentioned above is indeed based on ACTUALS where Service delivery targets are constant throughout the year. This is very much a simplistic view of "Workload vs FC shrinkage % vs Actual shrinkage%" to demonstate our scenario and to show our challenge of managing shrinkage to the required target levels.

Apart from the reasons given above for the seasonality changes, we have yet to complete a detailed analysis and would be interested if anyone else had?



Call Centre Helper

We have written an a...
We have written an article on How to calculate call centre shrinkage that discusses what should be included and what should not. We have also built in the shrinkage calculations into our Online Erlang calculator.

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