Emails SL Calculation With TAT

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The role of TAT (Turnaround time)

Good Morning!

Emails/day = 500

AHT = 12 min

FTE Hrs = 7.5 (90% Occ)

Shrinkage = 10%

Required agents:

(500*12/60)/(90%*7.5)/(1-0.1) = 16

I wish to know is it the only calculation or do we also include some other factors into it. It would help if you could explain.

And what is the role of TAT (Turnaround time) and where do we include it to see the impact on SL.

Erlang calculator to see the impact on Service Leve

Hi Sushil

You need to run it through an Erlang calculator to see the impact on Service Level.

There is a free one here New Excel Based Erlang Calculator – with Maximum Occupancy

It says calls but could just as easily be emails.

Incoming rate = 500 / (7.5 *0.90)/2 = 37 per half hour

Average duration = 720 seconds

Assume 80% of emails answered in 3600 seconds (1 hour)

Calculator says 16 agents

Agents needed = 16 / (1 – 0.10) = 17.7 Agents

With thanks to Jonty

What Formula

Could you share what formula you would use if the response time / TAT is 4 hours instead of 10 hours. I just want to validate my math.

How would I calculate FTE required by 30 minute / 60 minute interval. I have e-mail volume by interval. Average handling time is 840 seconds. Response time is 4 hours. Can you help?

With thanks to dnljvnnrmn

Author: Jonty Pearce