The standard bartending guideline for party drink planning is 1 drink per person for the first hour and 0.5 to 1 drink per person for each subsequent hour. This means a 3-hour party for 40 guests requires approximately 80 to 120 drinks total, depending on your crowd and the style of event.
Converting that total into bottles, cases, and liters depends on which beverages you are serving. A standard 750ml wine bottle yields 5 glasses. A case of beer contains 24 bottles or cans. A liter of spirits makes approximately 17 standard cocktails (1.5 oz pour). These conversion factors let you translate your per-person estimate into a precise shopping list.
This calculator accounts for event type (cocktail party, dinner, casual gathering), duration, and the beverage categories you plan to serve. It outputs the total number of drinks needed, plus the equivalent in wine bottles, beer cases, and spirit liters, giving you everything you need to stock the bar with confidence.
The calculator uses the standard 1-drink-first-hour, 0.75-drink-subsequent-hours formula. Cocktail parties use the higher end of the range (1 drink per subsequent hour) because drinking is the primary activity. Dinner parties use a lower rate (0.5 per subsequent hour) because food slows consumption. Casual gatherings fall in the middle. The tool converts the total drink count into wine bottles (5 per bottle), beer units (24 per case), and spirit liters (17 per liter).
Run the calculator 1 to 2 weeks before your event so you have time to shop sales and order specialty items. Most liquor stores accept returns on unopened bottles, so buying 10 to 15 percent more than the calculator suggests is a safe strategy that costs nothing if the extra goes back. For events with a mix of drinkers and non-drinkers, reduce the guest count by 15 to 20 percent before entering it into the calculator to account for non-alcohol guests.