How many pizzas do I need for 20 people?

For 20 adults eating 3 slices each from a large pizza (8 slices), plan for about 8 large pizzas.

How many slices are in a large pizza?

A standard large pizza (14 inches) has 8 slices. An extra-large (16-18 inches) typically has 8-10 slices.

How much pizza should I order per person?

Plan for 2-3 slices per adult and 1-2 slices per child. Increase to 3-4 slices per person for college-age guests or events without other food.

How do I calculate how many pizzas I need?

Multiply the number of guests by 3 (average slices per person), then divide by 8 (slices per large pizza). Round up to the nearest whole number.

Pizza Calculator | How Many Pizzas Do I Need?

Input Parameters

Number of Attendees

Slices Per Person

Pizza Size

Total Pizzas Needed

-- slices needed ÷ -- slices per pizza

Pizza Type Breakdown

Pro Tip

When feeding younger children, ask the pizzeria to double-slice your pizza.

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How many pizzas do I need?

The short answer: take your guest count, multiply by 2.5 slices per person, and divide by the number of slices in your pizza. Round up. That gives you a safe starting number for most groups.

The longer answer depends on who's eating. A room full of hungry teenagers will go through pizza twice as fast as a table of adults at a work lunch. Kids under 10 eat about 1.5 slices each. Adults average 2 to 3. If you're feeding a sports team after a game, plan for 4.

Slices per pizza by size

A medium pizza has 6 slices. A large has 8. An extra-large has 10. These numbers come from the standard cuts at most national chains, though your local shop might cut differently. When in doubt, ask.

Large pizzas are almost always the best value per square inch. A large is typically 14 inches across, giving you about 154 square inches of pizza. A medium is 12 inches (113 square inches). You get 36% more pizza for usually 20-30% more money. The math favors going big.

Planning by occasion

Kids' birthday parties: Plan for 1.5 slices per child and 2 slices per adult. Kids fill up on cake and snacks, so pizza goes further than you'd expect. For 15 kids and 10 adults, that's about 6 large pizzas.

Office lunches: People eat less pizza when there are other options on the table. If you're also ordering salads or sides, drop your per-person estimate to 2 slices. For a 20-person lunch with sides, 5 large pizzas is plenty.

Game day and watch parties: Plan for 3 slices per person minimum. People graze during long events, and cold pizza is still good pizza. Better to have leftovers than to run out during the fourth quarter. For 12 people, grab 5 large pizzas.

Graduation parties and large groups: For 50 or more guests, the calculator saves you real money. The difference between ordering 15 and 20 pizzas is $50 to $75 depending on your shop. Get the number right and spend the savings on drinks.

The type split matters

If you're ordering for a mixed group and you don't know everyone's preferences, a safe split is 40% cheese, 30% pepperoni, and 30% of a third option like sausage or veggie. Cheese is the universal fallback that nobody refuses.

For groups with dietary restrictions, keep at least one pizza fully vegetarian. If someone asks for gluten-free, most chains offer that now but it usually comes in a smaller size, so adjust your count.

Tips for getting the order right

Order 10-15% more than the calculator says if you want leftovers. Cold pizza the next morning is half the reason people order pizza in the first place.

Call the restaurant at least an hour ahead for orders over 10 pizzas. Walk-in orders that large can take 45 minutes or more and the kitchen may not be ready.

Check for deals before you order. Most chains run specials on large pizzas, and the per-pizza price drops when you order in bulk. A coupon on 15 pizzas adds up fast.

Helpful guides

Our complete guide to ordering pizza for a party covers per-person estimates, topping strategies, and common mistakes to avoid.

Not sure what size to order? The pizza size comparison guide breaks down area, cost per square inch, and chain-by-chain differences so you get the best value.

Slice counts vary more than you think. Our guide to how many slices are in a pizza covers every major chain and cut style.

Feeding a big group? Start with our guides for 20 people, 30 to 50 people, or 100 people.