How Many Pizzas Do I Need for a Party?
The reliable method is people × slices each ÷ slices per pizza, rounded up. The useful part is choosing assumptions that match your party rather than blindly using one fixed rule.
Start with slices, not pizzas
Pizza diameter alone does not tell you how many people it feeds. Different restaurants cut differently and some pizzas are much more filling than others. Check how many slices you will actually receive.
Separate adults and children when it matters
A mixed party is easier to estimate if adult and child slice allowances are separate. Teenagers may need the adult allowance; very young children may need less.
Pizza as the meal versus pizza as one option
If pizza is the whole meal, use a larger per-person allowance. If it sits beside substantial sides, buffet food or dessert, lower the pizza allowance rather than ordering the full meal quantity plus all the extras.
Round the order, not the people
Calculate the expected slices first and only then round up to whole pizzas. This makes the contingency visible instead of quietly adding extra people to the headcount.
Example
Fifteen adults × 3 slices plus eight children × 2 slices = 61 slices. If the pizzas are cut into eight slices, 61 ÷ 8 = 7.625, so order eight pizzas before any deliberate extra allowance.
Use the Pizza Party Calculator to change each assumption.