Shrinkage is the share of paid hours your agents are not available to take calls. Industry shrinkage runs at about 30% of paid time (Call Centre Helper), which means a 100-person contact centre is fielding roughly 70 people on the phone at any moment.
It is the number most staffing plans get wrong, and it fails in one direction: always short, never over.
What counts as shrinkage
Shrinkage splits into two kinds, and confusing them is how forecasts drift.
Planned shrinkage you know about in advance — holiday, training, scheduled coaching, team meetings, system downtime you booked. This belongs in the roster before the week starts.
Unplanned shrinkage you cannot schedule — sickness, lateness, unscheduled breaks, attrition mid-month, the twenty minutes after a difficult call. This is what you carry a buffer for.
Both are shrinkage. Only one is forecastable, which is why a single blended percentage hides the problem: a centre with 10% planned and 20% unplanned is run very differently from one with 25% planned and 5% unplanned, even though both report 30%.
Why it compounds
Shrinkage is a divisor, not a subtraction, and that is the part people get wrong.
If Erlang C says you need 50 agents on calls at 30% shrinkage, you do not roster 50 + 30% = 65. You roster 50 ÷ 0.70 = 72. The difference is seven people, and it is the difference between hitting service level and missing it every Monday.
The gap widens as shrinkage rises. At 40% shrinkage the same 50 agents need 84 rostered. Every point of shrinkage costs more than the last.
Measuring your own rather than assuming 30%
The 30% figure is a starting point, not your number. Calculate it as:
Shrinkage = 1 − (hours actually available for calls ÷ total paid hours)
Run it per interval, not per month. Shrinkage is not flat across a day — it spikes at shift changes, over lunch, and at the end of the week. A monthly average tells you your cost base; an interval-level figure tells you why 11am fell over.
The shrinkage calculator works it out from your own hours, which is more useful than borrowing a benchmark.
What actually moves it
Most shrinkage-reduction programmes target the wrong half. Unplanned shrinkage responds to management — adherence coaching, tackling the causes of absence, fixing the systems that make agents wait. Planned shrinkage mostly does not, because training and holiday are obligations, not waste.
The realistic win is moving planned shrinkage rather than removing it: run training in the quiet interval instead of the peak. Same hours, different hour.
And some apparent shrinkage is occupancy in disguise. If agents are logged in and idle because the forecast was heavy, that is overstaffing, not shrinkage, and the fix is the forecast.
Frequently asked questions
What is a good shrinkage rate? Around 30% is the common industry figure (Call Centre Helper). Materially below that usually means something is not being counted rather than that the centre is unusually efficient.
Does shrinkage include after-call work? No. After-call work is part of handling a call and belongs in average handle time. Shrinkage is time not spent handling calls at all.
Should shrinkage be applied per interval or per day? Per interval. A daily average hides the shift-change and lunch peaks that cause most service-level misses.
Why does a small rise in shrinkage cost so many agents? Because it divides rather than subtracts. Going from 30% to 35% shrinkage raises the rostered headcount for 50 on-call agents from 72 to 77.
