Staffing Calculator for Email queues

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Deputy Manager - Workforce Management

Accenture Services Pvt Ltd


Is Erlang suitable to estimate agents for email queues, where the SLA may be 2 hours? So in the calculator if the SLA is set to 100% in 7200 seconds, would it produce a viable result?

Would you recommend another approach?

GPR Consulting

Hi Sayan,

Erlang C calcualte the optimum number of resources reruired to accomplish a number of tasks across a time interval, so emails would be perfectly OK within these paramaters. The thing to watch out for is the resoruces and the volume of mails... it's perfectly OK to say 7200 seconds, but the key number will also be the average amount of time it takes an agent to complete an email. So you will need to time track the time from when the agent opens up the email, to the time they resolve it and send a response back. If you can't track that, then you might struggle with doing the correct calculation.

Let me know if I can help any further.


Deputy Manager - Workforce Management

Accenture Services Pvt Ltd

Thanks Gene.

The AHT which we have tracked is ~ 20 mins. So, if the TAT is around 2 hrs (i.e. 100% of the emails to be answered in 2 hrs) and with an AHT of 20 mins, Erlang C will give us the correct figure for agents required?

Please note, we do know the day of week and interval-wise forecast (i.e volume) per 30 mins interval.

Regards - Sayan

GPR Consulting

Hi Sayan,

Yes it should. You simply need to replicate the same paramaters you use in your inbound phone calls to your inbound emails (number in queue, number of agents, average handling time, number of new emails per interval, etc.)

Erlang C can be applied regardless of the length of time involved. Supermarkets use Erlang C to calculate the number of tills required at certain time of the day as well as civil engineers who design sidewalks or motorways for traffic... so emails will work perfectly well too.

Good luck, Sayan!


Deputy Manager - Workforce Management

Accenture Services Pvt Ltd

Thanks Gene and apologies for the delayed response.

Need some more help regarding this. Using erlang, I have been able to determine Agents required as per the earlier discussions.

Now, what i need is a calculator sort of a thing, where i will put -

Weekly /day of week volume

Intraday pattern


Shrinkages & Occupancy


and the calculator will tell me the number of agents required to cater to the volume.

Regards - Sayan

GPR Consulting

Hi Sayan, sorry for the delay on my end... its been a bit hectic.

Things like work volume, AHT, etc, are elements that directly calculate the erlang requirements. So, if you're using MS excel to determine this, I would recommend a crash course on how to produce macros. From there, you can have seperate pages which will have your work levels over an interval, number of staff, aht, etc... and then run a macro which will run an erlang C calculation based on all of the variable factors you want to throw at it.

Unfortunately, I wont be able to go over the exact formulas to apply here in this forum, as doesnt allow me to use mathematical formulas in the reply. I am sure there are places on the internet which will help you get there.


GPR Consulting



Hi there! I'm having trouble with Service Level. I manage a chat program. I use the Erlang C. Unique to my center is that an agent handles 3 windows at a time. When I use the Erlang C to determine staffing per 30 min interval, I end up understaffed. Help.

GPR Consulting

Ah, now that it begins to get a little tricky... So you have agents handling 3,4, even 5 chats at a time, are they doing any other jobs during this time?


Hi all! I want to plug in the TAT to calculate how many agents I would require to handle a certain number of the cases per day.

I've done the time & motion to determine time taken to fulfill each request (~ 20 mins).

Given the TAT is, e.g. 4 days, in days and each case might be at different levels of progress (open, WIP, pending etc) how do I arrive at day-to-day staffing requirement?

Operations Manager

Hi ,

hope you guys can help me out.

I need to calculate the amount of staff needed for my process..

The kind of work is that we manage return request for an online seller.

currently I have 6 people who are logged in to work for 9 hours a day excluding the break of 1 hour.

they avg time spent on each return is 7 to 8 mins and out of the 100 returns assigned to each individual they work on at least 60 unique cases a day with multiple emails sent on each unique case.

SO I really need help to figure this out.


It looks as though you have a few problems here.

1. People logged in for 9 hours a day with an hour for lunch is too much. They are going to be burnt out and the quality will go down. If you were based in the UK and doing this for 5 days a week you would probably be breaking labour laws.

By my quick calculations you could probably handle 57 cases a day. If you are allocating 100 then you are seriously understaffed and I would guess that workload is backing up.

Sounds like you need to build the business case for more staff.

Operations Manager

Thanks for the reply Simon,

thing is they are logged in for 10 hours a day and out of the 10 hours they work 9 hours and have a 1 hour break divided in to 15-30-15 duing the day.

Can you help me with a staffing plan and guide me as to how to go about this. I have been able to make a staffing plan and requirement for calls based processes however this email one has got me thinking.


Good Day!

How do i calculate FTE required for Email queue?


Call Centre Helper

The best approach would be to use the multi-channel staffing calculator which will enable you to work out the FTE requirement for email.

Will occupancy cross 100%
My question to calculate occupancy for 1hr interval ,consultant target is or eg:17 emails/chats (3.52min/e-mail,chat) if consultant do below target occupancy lies below 100% and consultants do for eg:18 emails then his occupancy will be 105% is this correct ,please help me and is there any way occupancy should not cross 100%

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