To forecast how many kegs you need, multiply four numbers: expected guests x the share who drink x drinks per person per hour x the number of hours. Divide the total drinks by a keg's serving count (a 1/2 barrel pours ~165, a 1/6 barrel ~55) and round up. That one formula handles a weekly office tap or a 300-person event. Here is how to use it without overthinking.
The keg forecasting formula
Total drinks = guests x drinking rate x drinks per hour x hours. Then kegs = total drinks divided by servings per keg, rounded up. Example: a 3-hour office party with 80 expected, 70% who drink, at one drink per hour is 80 x 0.7 x 1 x 3 = 168 drinks — almost exactly one 1/2 barrel (~165). So order one 1/2 barrel plus a 1/6 backup, which absorbs the days your estimate runs light.
| Keg size | ~12 oz pours | Covers (typical office event) |
|---|---|---|
| 1/2 barrel | ~165 | ~80-100 guests |
| 1/4 barrel | ~82 | ~40-50 guests |
| 1/6 barrel (sixtel) | ~55 | ~25-30 guests, or a backup |
Pick your drinking rate honestly
The number that throws forecasts off most is the drinking rate. Office afternoons run light — plan about one drink per person per hour and assume a real chunk of the room (often 30 to 40%) will not drink alcohol at all. Evening events run heavier: 1.5 to 2 drinks in the first hour, tapering after. When in doubt, forecast the alcohol on the lighter side and cover the gap with non-alcoholic options.
Forecast the non-alcoholic side too
Plan for the 30 to 40% who are not drinking beer, or you will over-order alcohol and under-serve the room. A non-alcoholic keg — cold brew or kombucha — or a stocked fridge of non-alcoholic drinks covers them, and it doubles as the daytime option so the tap earns its keep before 5 p.m.
Standing office tap vs one-off event
For a recurring office tap, forecast a weekly rate instead of a single event: track how fast each keg empties, then set a reorder cadence — see our guide on preventing office keg shortages. For a one-off event, forecast the single occasion and add a backup keg. Either way, browse beer kegs and the full keg selection by size.
Let Mike's size it with you
We have sized kegs for San Francisco offices and events from our shop at 5084 Mission St since 1959 — tell us the headcount, the hours, and the vibe, and we will translate it into kegs, taps, and CO2. We deliver same-day in SF for orders by 9 a.m., plus East Bay (Tuesdays) and South Bay (Wednesdays). Need the per-event math? Our 100-person party guide walks through a worked example.
How many kegs do I need for 50 people?
For a 2 to 3 hour event, plan roughly 75 to 150 drinks (50 guests x about 1 to 1.5 drinks per hour x the hours, minus non-drinkers). One 1/2 barrel (~165 pours) comfortably covers 50 with room to spare.
How do I forecast kegs for a recurring office tap?
Track how fast each keg empties — label the tap date and note when it kicks. After a few kegs you will have a weekly rate; set your reorder point a few days ahead of running dry.
Should I round keg orders up or down?
Round up, and add a small backup. Running short mid-event is far more disruptive than a little leftover, and an untapped keg keeps for weeks.