To work out how much alcohol to buy for a party, start with one number: about one standard drink per guest per hour. Multiply guests by hours to get the total drinks, split that across beer, wine and cocktails, then convert each part into bottles and cans. The party drink calculator does the whole chain and gives you a shopping list.
The one-drink-per-hour rule
The planning figure most hosts use is one standard drink per guest for each hour of the party:
Total drinks = guests × hours × drinks per hour
For 20 guests at a four-hour party, that is 20 × 4 × 1 = 80 drinks. It sounds like a lot, but it covers the people who drink steadily and the ones who nurse one all night, averaged out. Nudge the rate up to about 1.5 for a heavy-drinking crowd or a big celebration, and down to about 0.75 for an afternoon event or a mixed group with drivers and non-drinkers.
Split the drinks by type
Once you have the total, decide roughly what share is beer, wine and cocktails. A balanced crowd often lands near 50% beer, 25% wine and 25% spirits, but shift it to match the event: a cookout leans beer, a dinner leans wine, a cocktail evening leans spirits. From that split you get a drink count for each type.
Convert drinks into bottles and cans
Each type converts differently:
- Beer. One drink is one can or bottle, so 40 beer drinks means 40 cans. Buy by the case and round up.
- Wine. A 750 ml bottle pours about five glasses. Divide the wine drinks by five to get bottles: 20 glasses is four bottles.
- Spirits. A 750 ml bottle makes about 16 cocktails at a 1.5 oz pour. Divide the cocktail drinks by 16: 20 cocktails needs two bottles, plus the mixers and garnishes.
Always round up. An unopened bottle keeps for the next party, but running dry mid-evening does not.
Do not forget the ice
Ice is the thing that runs out first. Plan on about 1 to 1.5 pounds per guest, and more if you are icing down cans and bottles in tubs as well as using it in drinks. For 20 guests that is around 30 pounds. It is cheap, so overbuy.
Build your shopping list
Enter your guests, hours and mix into the party drink calculator and it turns the whole thing into beers, wine bottles, spirit bottles and ice you can copy straight to a list. Treat the numbers as an estimate, buy a little extra, offer water and soft drinks alongside, and serve responsibly.
