Estimate drinks needed per guest for a party.
Drink planning uses a simple and reliable rule: guests average about two drinks in the first hour as they arrive and settle, then roughly one per hour after. Applying that only to the share of guests who actually drink alcohol avoids the usual over-buying, and a 15 percent margin covers spillage, top-ups and the guest who arrives thirsty. Converting servings to bottles depends on your pour: a 750 ml bottle gives five 150 ml glasses of wine but only about sixteen 45 ml spirit measures. Non-drinkers need substantially more soft drinks per hour than drinkers, since soft drinks are consumed faster.
Servings needed
Drinks = (1 + (hours - 1)) x guests x drinker share x 1.15
Bottles
Bottles = ceiling(servings / floor(bottle ml / serving ml))
A quantity planning tool, not a guide to safe consumption. Serving alcohol carries legal responsibilities that vary by jurisdiction, including age verification and liability for guests who drive. Always provide substantial food, free non-alcoholic options and water, and arrange alternative transport for anyone who has been drinking.
Guests arrive, are handed a drink, and finish it quickly while the room fills and conversation starts. Consumption then settles to roughly one drink an hour. Planning a flat rate across the whole party consistently leaves you short at the start and over-supplied at the end.
More per hour than for drinkers, because soft drinks go down faster — plan around one and a half servings an hour. Also allow half a serving an hour for the alcohol drinkers, who will alternate with water or a soft drink. Running out of non-alcoholic options is a very common oversight.