Pizza Party Calculator
Work out how many pizzas to order for your party from guest count, appetite and slices per pizza — with leftovers.
How it works
slices needed = guests × slices per person · pizzas = ceil(slices needed ÷ slices per pizza) · leftovers = pizzas × slices per pizza − slices needed
Multiply the guests by how many slices each will eat, then divide by the slices in one pizza and round up — you cannot order a fraction of a pizza. Rounding up is what creates the leftover slices, which the calculator reports so you know how much spare you are buying. Adjust the appetite setting for the crowd: kids and grazers lean light, while teenagers and game-day guests run hungry.
Worked example
10 guests with average appetite eat 3 slices each — 30 slices. At 8 slices per pizza that is 30 ÷ 8 = 3.75, rounded up to 4 pizzas (32 slices), leaving 2 slices over.
Frequently asked questions
How many slices does the average adult eat?
About 3 slices of a standard pizza is a common planning figure. Light eaters and children trend toward 2, while very hungry guests or a late dinner can push it to 4.
Should I round up or down?
Always up — running out is worse than a few leftovers, and cold pizza keeps well. The calculator rounds up for you and shows the spare slices.
Do different pizza sizes change this?
Yes — set the slices-per-pizza field to match. A large might be cut into 8, an extra-large into 10 or 12, so the same number of pizzas feeds more people.
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This calculator is for educational purposes. Double-check important results before acting on them.