How much alcohol for a party?

The rule the numbers come from

Caterers plan two drinks per guest for the first hour, then one drink per hour after that. It sounds generous, but averaged over a whole party it's about right: some guests nurse one glass all night, others make up for them. For 25 guests over 4 hours that's 2 + 1 + 1 + 1 = 5 drinks each, 125 drinks total. The crowd switch nudges that up or down a quarter for a mellow dinner party versus a wedding dance floor.

Turning drinks into bottles

• Beer: one drink is one 330 ml can or bottle. The easy half of your shopping.
• Wine: a 750 ml bottle pours five 150 ml glasses. Split roughly 60/40 white-and-bubbly to red for a mixed crowd, more white in summer.
• Spirits: a cocktail carries about 60 ml of spirit, so a 750 ml bottle makes around 12 drinks. Batching three or four classics beats a free-pour bar on cost, speed and consistency.

The mixed-bar table above assumes half the drinks are beer, a third wine, and the rest cocktails, which matches how most house parties actually drink. Shift the ratio toward whatever your crowd loves; totals are what matter.

The things people forget

• Ice, always ice. Plan about 1 kg per guest — more if you're also chilling bottles in a tub. It's the cheapest thing on the list and the first thing to run out.
• Mixers and water: roughly a litre of mixers per guest across soda, tonic and juice, plus water on the bar so nobody has to ask.
• Glasses: count two per guest; they get abandoned.
• Buy long: shops take back unopened bottles, so rounding up costs nothing but a receipt.

If you're batching cocktails

Once you know the drink count, pre-batch. A batched Negroni or Margarita pours in five seconds, tastes identical from first glass to last, and frees you from playing bartender at your own party. The batch calculator scales any recipe to your headcount and tells you exactly how much dilution water to add.