The formula: guests × slices per person ÷ slices per pizza
The number of pizzas you need comes from three inputs, and only one of them is about the pizza itself.
- Guests: count adults and children separately. Children eat roughly two-thirds of an adult portion.
- Slices per person: use 3 for an adult main meal, 2.5 when sides are heavy, and 2 per child.
- Slices per pizza: a large pie is usually 8 slices, an extra-large 10, and a party-cut pie 16 squares. Always confirm with the shop.
For 20 adults at 3 slices each: 20 × 3 = 60 slices. With 8 slices per large pizza: 60 ÷ 8 = 7.5, so order 8 pizzas.
Pizzas for 20 people: three real scenarios
| Scenario | Slices per person | Total slices | Large 8-slice pizzas |
|---|---|---|---|
| 20 adults, pizza is the meal | 3 | 60 | 8 (7–8) |
| 20 children | 2 | 40 | 5 (4–5) |
| 20 mixed guests with salad, bread and dessert | 2.5 | 50 | 6–7 |
The middle row is the one people get wrong most often. Kids rarely finish three slices of a large pie, and a birthday table usually has cake waiting. Ordering 8 pizzas for 20 children wastes food and money.
Adjust for how your shop cuts the pizza
Slice count matters more than pizza diameter. Two 16-inch pizzas cut differently can feed very different numbers of people. Divide your 60-slice target by the shop's actual cut.
| Pizza size or cut | Slices per pizza | Pizzas for 20 adults (60 slices) |
|---|---|---|
| Medium 12 inch | 6 | 10 |
| Large 14–16 inch | 8 | 8 |
| Extra-large 18 inch | 10 | 6 |
| Party cut (squares) | 16 | 4 |
Party-cut squares look like more food because guests take several small pieces, but the total volume is similar. If you order party cut, expect people to take 4 to 5 squares instead of 3 slices.
How to order 8 pizzas for 20 people
- Mix the toppings: about 60% crowd-pleasers (cheese, pepperoni) and 40% variety. Nobody is offended by plain cheese.
- Include 1–2 vegetarian pies: a veggie or margherita pizza covers dietary needs without a separate order.
- Ask for a mix of cuts if you have both adults and kids: one or two party-cut pies keep small hands happy.
- Time the pickup: pizza holds well for about 30 minutes. If the party runs long, order in two waves rather than letting 8 pies go cold.
- Plan drinks alongside: 20 guests typically need about 5 twelve-packs of soda or 6–8 two-liter bottles — see the party drink calculator for exact counts.
For a general-purpose tool that handles any guest count, topping mix and slice size, use the pizza party calculator. Ordering for a bigger group? See how many pizzas for 40 people.
More free party calculators
Pizza for 20 people: common questions
How many pizzas for 20 people?
For 20 adults eating pizza as the main meal, order 8 large pizzas cut into 8 slices each. That gives 64 slices against a 60-slice target (20 people × 3 slices), so 7 to 8 pizzas covers the group with a small buffer.
How many pizzas for 20 kids?
Plan 2 slices per child, so 20 kids need about 40 slices. With 8-slice large pizzas that is 5 pizzas. Younger kids often stop at 1 to 2 slices, so 4 to 5 pizzas is a practical range.
How many slices of pizza per person should I plan?
Plan 3 slices per adult when pizza is the meal, 2 slices when you are also serving salad, bread or pasta, and 2 slices per child. These are standard catering starting points rather than guarantees.
How many pizzas for 20 people if there are sides?
With a filling salad, breadsticks, wings or pasta on the table, drop to about 2.5 slices per adult. That is 50 slices, or 6 to 7 large 8-slice pizzas for 20 guests.
How many pizzas for 20 people if the pizzas are cut into 10 or 12 slices?
Divide total slices by slices per pizza. For 60 slices: 6 pizzas at 10 slices each, or 5 pizzas at 12 slices each. Ask the shop how they cut before you order so you do not overbuy.
Should I order extra pizza for 20 people?
Order one extra pizza beyond your calculation if the group drinks alcohol, the event runs over three hours, or you want leftovers. Pizza is cheap per head, and running out is the most common party mistake.