Party Drink Calculator

For a four-hour evening party where roughly 40 of the 50 are drinking, plan on about 200 drinks in total — near enough 84 beers, 14 bottles of wine and 3 bottles of spirits. The split depends on what your crowd drinks, which is why the calculator lets you move it. The total is the part that stays stable.

The catering rule that holds up best is two drinks in the first hour and one per hour after that. People arrive thirsty and slow down once they have food in front of them. A four-hour party therefore works out at about five drinks per drinking guest, not four.

A 750 ml bottle gives five standard 5 oz / 150 ml glasses. For 20 wine drinkers over three hours you need roughly 80 glasses, which is 16 bottles. Buy in even numbers of red and white unless it is a hot day, when whites and rosés run out first.

Plan on 1.5 lb (about 700 g) per guest, and 2.5 lb (about 1.1 kg) per guest in warm weather or outdoors. Roughly half goes into glasses and half into chilling bottles and cans. Ice is the single most underbought item at any party.

Assume about 70–75% of adults will drink alcohol at a general party, lower at a family or daytime event. Put the rest in the 'adults not drinking' box — they still need a drink in their hand, and the calculator accounts for that separately rather than ignoring them.

Per serving, spirits are usually cheapest and beer most expensive, because one 750 ml bottle stretches to around 16 drinks while a case of beer gives 24 much larger ones. Spirits also need mixers, ice and someone pouring. A limited bar of one beer, one white, one red and one cocktail is the reliable way to cut the cost without anyone noticing.

The consumption rate is the standard event-planning rule: two drinks per guest in the first hour and one per hour after, which is also what the common Guests × (Hours + 1) shorthand produces. Bottle yields follow bar convention — five 5 oz glasses from a 750 ml bottle of wine, and 16 rather than the arithmetic 17 measures from a 750 ml bottle of spirits, because event planning rounds down to absorb spillage and heavy pours. Cocktails built on a 2 oz base give about 12 to the bottle instead.

Buy the numbers above and ask your store about sale-or-return before you commit — most will take back unopened wine and beer, which makes overbuying free. Where that is not an option, add a margin on beer and soft drinks rather than on spirits, since those are the ones you will actually use afterwards.