"How much should I buy?" is the first question of every party that serves drinks, and it has an actual formula — the same one bartenders and caterers use. Learn it once and fifty-person parties stop being a leap of faith.
The formula
Total drinks = guests × (2 + (hours − 1)) — two drinks in the first hour, one each hour after.
Fifty guests, four hours: 50 × 5 = 250 drinks. Apply a crowd factor (light weeknight crowds ~75%, big celebrations ~125%) and you have a planning number with real track record behind it. Our drink calculator runs the whole thing including container conversions.
Splitting the 250
Know your crowd; when in doubt, the all-purpose split is 40% beer, 35% wine, 25% spirits:
- Beer: 100 drinks = ~8.5 six-packs → buy 9 (54 cans), or ~8 twelve-packs for bigger groups.
- Wine: 87 glasses ÷ 5 glasses/bottle = 17–18 bottles, weighted red/white/rosé by season.
- Spirits: 62 drinks ÷ 16 drinks per 750ml ≈ 4 bottles — two of the main spirit, one each of two others. Standard mixers at ~2 liters per bottle of spirits.
The list everyone forgets
- Non-alcoholic for everyone: plan every guest at 2 NA drinks in the first two hours — sparkling water, soda, a big batch mocktail. Twenty percent of any crowd drinks zero alcohol; a hundred percent get thirsty.
- Ice: ~1.5 lbs per guest minimum, more outdoors (the ice calculator exists for a reason).
- Garnish and staples: lemons, limes, and a jigger. Free-pouring parties run 30% heavier on spirits — measured pours are both fair and economical.
Leftovers are a feature
Unopened wine and spirits return to the shelf; unopened beer goes to next weekend. Overbuying by one unit per category is cheap insurance — but the formula already bakes in a comfortable margin, so resist the legendary "just in case" fourth case. The guests who remember your party remember the host who was present, not the host with the deepest cellar.