Never run out of drinks at your party.
The standard rule: 2 drinks per person for the first hour, then 1 drink per person per hour after. This means a 4-hour party with 25 guests needs about 125 standard drinks. A standard drink is 12 oz beer, 5 oz wine, or 1.5 oz spirits. One 750mL wine bottle = 5 glasses. One 750mL spirit bottle = 16 cocktails. A case of beer (24) serves about 8 people for a 4-hour party. Always have 20-30% non-alcoholic options (water, soda, mocktails) — some guests don't drink. Buy ice: 0.5 kg per person. Most stores allow returns of unopened alcohol, so slightly overbuying is safer than running out.