How to use this calculator
Start by entering the number of adult guests. Choose an appetite level that best matches your crowd, light eaters at a brunch, average for a casual get-together, or hungry for a game-day party.
If kids are coming, toggle the kids option and enter how many. Kids average about 1.5 slices each. Select your preferred pizza size, toggle the sides option if you're serving other food, and adjust the price per pizza to match your local prices. The calculator instantly shows how many pizzas to order, total cost, and expected leftovers.
Pizza slices by size
| Pizza Size | Diameter | Slices | Best For |
|---|---|---|---|
| Small | 8 to 10 inches | 6 | Individual or 1 to 2 people |
| Medium | 12 inches | 8 | Small group of 2 to 3 |
| Large | 14 inches | 10 | Groups of 3 to 5 (best value) |
| Extra-Large | 16 to 18 inches | 12 | Large groups (most cost-effective) |
Tips for ordering for large groups
For parties of 15 or more, stick to large or extra-large pizzas for the best price per slice. A good rule of thumb is to keep about one-third of your order as cheese or pepperoni, they're universally liked and safe for picky eaters.
Ask about dietary needs before ordering. Having at least one vegetarian and one gluten-free option shows you're thinking about everyone. Many pizzerias offer discounts on orders of 10 or more pizzas, so don't be afraid to ask.
Timing matters too. Place your order at least 24 hours ahead for groups over 10. On game days, holidays, or Friday evenings, order even earlier. Stagger delivery times if your event runs long so guests always have fresh, hot pizza.
Frequently asked questions
How many pizzas do I need for 20 people?
For 20 adults with average appetites, you'll need about 8 large pizzas (10 slices each). That gives everyone roughly 3 slices. If your group is especially hungry, go with 10 pizzas to be safe.
How many slices of pizza does the average person eat?
The average adult eats about 3 slices of pizza. Light eaters may have 2 slices, while hungry adults can eat 4 or more. Children typically eat about 1 to 2 slices on average.
Should I order more pizza if I'm not serving sides?
Yes. When pizza is the only food available, guests tend to eat about 20% more. If you're serving salads, wings, breadsticks, or other sides, you can reduce your pizza order by about 20%.
What is the best pizza size to order for a large group?
Large pizzas (typically 14 inches, 10 slices) offer the best value per slice for group orders. Extra-large pizzas (16 to 18 inches, 12 slices) are even more cost-effective if your pizzeria offers them. Avoid ordering many small pizzas as you'll pay more per slice.