More FTE Maths

The following article is am edited re-post (with permission) written by Dan Rickwalder  – you can find the original HERE

This post is a follow-up from What the Heck is an FTE? check that post out if you missed it.

We all know that a full time employee works eight hours a day for a total of 40 hours in a week (or some other combination like 7.5 hours a day for 37.5 hours in a week etc.).  But this is easy maths, it only starts to get complicated when you want to figure out how many FTEs you need by interval.  To the left is an example of interval requirements by hour for a contact center that is open from 8 AM to 8 pm. How many people do you need for the day?

Well.....If people work 8 hours a day and I have a 12 hour day I need at least 6 to start and 8 to close so that gives me 14 in the middle of the day but I need 33 do I have to add 19 so I need 33!!!!

ummmmm...well that sorta works....but try explaining to your boss. and try extrapolating it across an entire week.  With a half day on Saturday...

Fortunately, there is an easy solution to this problem and it's just math.

To calculate the number of FTE's need in a day, simply add up the interval requirements and divide them by the number of hours you plan for an FTE in a day (in our case 8).  So if I add up all of my intervals I get a total requirement of 253.  That number is actually hours needed to handle calls so I have 253 hours need.  Divide that by 8 and you get 31.6 FTEs required.

To expand to a full week, you would just calculate the total hours for the week and divide by your weekly FTE number (in our case 40).  Like this:

I added up all of my intervals and got 1,094 hours.  I divided that by 40 hours per FTE per week to come up with a weekly FTE requirement of 27.35.  That's all there is to it.

But, As the genie in Aladdin said, "There are a few, uh, provisos, a, a couple of quid pro quos."

Some things you will want to keep in mind are that:

1. Interval requirements usually do not include shrinkage, so your 8 hours should be minus that.  In reality, I would use closer to 6.4 hours a day for an on phone FTE to accommodate 20% shrinkage.  The number does, however, include occupancy so that should be separated out. Some centres choose to only remove set off phone time like breaks and would then use 7.5 hours per day.  However, the reality is lower than that.
2. Your interval length may vary.  Most centres use 1/2 hour or 15 minute intervals.  In those cases, you must adjust for that.  An 8-hour FTE would be equal to 16 half hours or 32 15 minute intervals.  So you just need to divide your total hours by the right number
3. Part day shifts can mess you up. If we were only open 4 hours on Saturday, an FTE could only work a maximum of 4 hours, so you have to adjust your definition for the week and that day.  That gets a little complicated.
4. Likewise, part timers mess up your total hours per FTE per day or week.  You'll have to adjust for that too.