How to use this calculator
Enter everyone who will eat pizza, then choose an average number of slices per guest. Use the slice count from your pizzeria rather than assuming that all large pizzas have the same number of slices. Add an allowance if appetites are uncertain and enter the actual price per pizza.
The formula and assumptions
Guests × slices per guest → Multiply by (1 + extra / 100) → Divide by slices per pizza; round up
The calculator treats all slices as the same size. Three slices per person and eight slices per pizza are editable starting values, not universal serving rules. Only the final pizza count is rounded up. Cost uses the whole pizzas ordered and excludes delivery, tax and tips.
Worked example
For 30 guests eating 3 slices each, start with 90 slices. A 10% allowance increases this to 99 slices. At 8 slices per pizza, 99 ÷ 8 = 12.375, so order 13 pizzas. You receive 104 slices. At 12 per pizza, the estimated cost is 156 in your selected currency.
Before you order
If pizza is a snack alongside a buffet, reduce the slices per person. For mixed appetites, calculate a weighted average or run two estimates and add their slice totals before rounding. Separate vegetarian and allergy-friendly orders according to your guests; an extra pizza does not solve dietary restrictions.
Frequently asked questions
How many pizzas for 30 people?
With 3 slices per guest, 8 slices per pizza and 10% extra, the estimate is 13 pizzas. Change these inputs to match your menu and pizza size.
Does pizza diameter affect the result?
Not directly. The calculator counts slices. Bigger or smaller slices require you to adjust the slices-per-guest input.
Is delivery included?
No. Add delivery, tax and tips separately or include them in the party budget tool.
Planning estimates only. Adjust portions for your guests, menu and event. Confirm serving yields, prices and venue capacity with your suppliers.