Call Center Shrinkage and FTE Calculator
Shrinkage, the time people are paid but not on the phones, is where staffing plans quietly go to die. List what takes your team off the queue in whatever unit you track it in, and this turns it into one honest percentage, then into the heads and FTEs you actually have to schedule.
Heads to schedule at other shrinkage levels
Same number of agents on the phones, different shrinkage. The last column is what happens when somebody adds the percentage on top instead of dividing: that many people really are on the phones, and it is always short.
| Shrinkage | On schedule | Weekly FTE | Add-on-top heads | Really on phones |
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The math, with your numbers in it
- Working it out.
What is shrinkage, really?
Shrinkage is the share of paid time your people are not available to take calls. Some of it is whole days away: vacation, holidays, sick days. Some of it happens on days they are here: breaks, coaching, team meetings, training, the ten minutes the phone system decided to take a nap. None of it is wasted time (a floor without breaks or coaching would be a miserable place to work), but every minute of it has to be covered by somebody else, and that is why it belongs in the plan instead of in a surprise.
I have run a call center, and there is one mistake so easy to make that it gets its own calculator: a good forecast turned into a schedule with shrinkage bolted on wrong. The forecast says 14 agents on the phones, somebody writes down 14, and at 10:30 half the floor is on break. Uh-oh.
Why divide instead of adding a percentage?
Because shrinkage is a share of the people you schedule, not of the people you need. If 30% of scheduled time goes elsewhere, only 70% of the schedule is on the phones, so you need 14 ÷ 0.7 = 20 people to leave 14 on the queue. Adding 30% on top gives 14 × 1.3 = 18.2, round up to 19, and 19 people at 70% availability is 13.3 on the phones. Call Centre Helper's shrinkage guide makes the same point with 70 agents: the right answer is 100, adding gives 91. The gap grows with shrinkage, which the table above makes painfully clear.
Why compound days away with time on shift?
The classic spreadsheet adds every category straight up. That is exact when every item is measured over the same paid time, like the published example this page can load, where every row is in days per year. But breaks and coaching only happen on days people actually come in. Somebody on a two week vacation takes zero breaks! So this calculator counts the days away first, then applies the on-shift time to the days that are left: 1 − (1 − away) × (1 − on shift). The plain sum is shown too, so you can see how much it overstates (a little, usually, but it is your budget).
Which units should I use for each row?
- Minutes per day for things that happen every shift: breaks, the start-up routine, system time.
- Hours per week for recurring sessions: coaching, one-to-ones, team meetings, weekly training.
- Days per year for whole days away: vacation, holidays, sick days, jury duty, and big training blocks.
Use real numbers from your own reports where you have them. The example rows are there to show the shape, not to tell you what yours should be, because shrinkage swings a lot between teams and seasons.
What does the CFO question tell me?
Brad Cleveland's ICMI article walks through a center taking 790,000 calls a year at 3.5 minutes each: 46,083 hours of calls against 114,400 paid hours for 55 FTEs, so only about 40% of paid time is spent on calls. It sounds terrible until you break it down. Shrinkage takes its share first, and on the time that is left nobody can be busy 100% of it, because calls arrive at random and somebody has to be free when the next one rings. On top of that, the FTE count often includes supervisors, trainers and analysts who were never meant to take calls (the article makes this point too). Section 5 does that split with your numbers, so the next time finance asks, you have the answer ready.
Your homework: pull last month's actual shrinkage by category from your workforce reports, put it in section 2, and compare it with the number your schedule assumes. If they are more than a couple of points apart, you just found your missing people!