How to use this calculator
Enter the number of guests, duration and how many 250 mL servings each guest may drink per hour. Set your bottle size and extra allowance. This tool estimates one combined supply of non-alcoholic drinks; split that volume between water, juice and soft drinks yourself.
The formula and assumptions
Guests × hours × servings per hour → Multiply by 250 mL and extra allowance → Divide by bottle volume; round up
A serving is fixed at 250 mL, approximately 8.45 US fluid ounces. The editable default of one serving per person per hour is a shopping assumption, not hydration advice. Litres and US gallons describe the same volume. Bottle counts round up; the purchased volume and cost include those whole bottles.
Worked example
For 30 guests, 3 hours and 1 serving per hour, the base is 90 servings. With 10% extra, plan for 99 servings, or 24.75 L. In 2 L bottles, that requires 13 bottles, providing 26 L. At 2 per bottle, the purchase cost is 26.
Before you order
Outdoor heat, activity, children and access to tap water change what you need. This estimate excludes ice, drinks used in recipes and any drinks already supplied by the venue. Use actual bottle labels; US gallons and imperial gallons are different units.
Frequently asked questions
Does this estimate alcoholic drinks?
No. This calculator plans a combined volume of non-alcoholic drinks.
Does the result include ice?
No. Buy ice separately according to your coolers, storage time and supplier’s guidance.
Why does switching units change the bottle size?
It converts the same bottle volume between litres and US gallons. It does not change the physical bottle or the number needed.
Planning estimates only. Adjust portions for your guests, menu and event. Confirm serving yields, prices and venue capacity with your suppliers.