No secret serving rules. Just your guest count, your pour size, and a few transparent calculations.
Start with the liquid.
Guests × servings per guest × liquid per servingThat’s your base drink volume.
Use the amount of liquid in a pour. If a 350 mL cup will hold ice and 250 mL of lemonade, enter 250 mL. This calculator does not estimate ice displacement or melting.
“Servings per guest” is a number you choose for this particular drink. It is not a recommendation for how much anyone should consume. If you offer several drinks, give each its own share of the plan rather than assuming everyone takes every option.
Add a buffer once.
Base volume × (1 + extra allowance ÷ 100)That’s the drink volume including your extra.
The extra allowance is optional: zero is valid. It covers whatever uncertainty you decide to allow for. The example uses 10%, which is an editable starting point, not a measured standard.
Bottles are rounded up using the unrounded calculation, even if the displayed volume looks like an exact multiple. Total volumes display at most three decimal places in liters or gallons; bottle sizes show more digits. A positive total smaller than 0.001 is shown as “<0.001”. Downloaded and printed lists also retain the volume inputs in mL before display rounding.
Use a bottle size you can actually buy. For mixed bottle sizes, run separate plans; the calculator assumes one bottle size. A homemade drink can use the same math for equal-size containers, but this is not a recipe or ingredient scaler.
What happens at zero?
Zero guests or zero servings gives zero liquid, bottles and packaged space. Serving and bottle size must stay positive. Empty, negative or out-of-range inputs pause the results so an old shopping list cannot be mistaken for the current plan.
MAKING ROOM
Fridge volume is only a rough check.
Purchased volume × space multiplier = estimated packaged space
The editable 1.3× example adds 30% for packaging and gaps. Five 1.5 L bottles × 1.3 = 9.75 L of estimated space. Compared with 25 L of available space, that is 39%.
The estimate assumes all purchased bottles need room at once. Container shape, shelves, doors and other contents affect actual fit. A volume calculation cannot tell you whether a tall jug fits on a short shelf. Measure container dimensions and shelf clearance; do not treat this as a fit guarantee, storage instruction or food-safety guide.
You can set available space to zero. The calculator then shows no percentage rather than dividing by zero. Space here means usable empty volume you estimate, not the appliance’s total advertised capacity.
METRIC ↔ US CUSTOMARY
Same plan. Different units.
Metric uses mL for pours and L for bottles and space. US mode uses US fluid ounces for pours and bottles, and US liquid gallons for the total and fridge space. Switching the view keeps the stored volume unchanged; editing a converted field uses the new value you enter.
UNIT
VALUE USED
1 liter
1,000 mL
1 US fluid ounce
29.5735295625 mL
1 US liquid gallon
3,785.411784 mL = 128 US fl oz
1 US customary cup
8 US fl oz ≈ 236.588 mL
A “serving” is your chosen pour, not a standardized measuring cup. US customary units here are different from Imperial units and from a rounded 240 mL measuring cup. Fluid ounces measure volume, not weight ounces.
Unit reference: NIST Guide to the SI, Appendix B.8 (published conversion table; checked October 22, 2026). NIST lists rounded conversion factors; this calculator retains the full US customary factors shown above. Planning formulas, defaults and examples are original to Party Measure and have not been physically tested.
A list that leaves with you.
The calculator downloads a plain-text shopping list with your current assumptions, totals and checked items. Print produces the same planning sheet without the navigation or form. Inputs and checkmarks stay in memory only and reset when you reload. There are no accounts, cookies, analytics, external fonts or API requests.
Party Measure