Quick reference table and answers based on 3 slices per person and 8 slices per large pizza.
| Guests | Large pizzas |
|---|---|
| 10 people | 4 pizzas |
| 15 people | 6 pizzas |
| 20 people | 8 pizzas |
| 25 people | 10 pizzas |
| 30 people | 12 pizzas |
| 40 people | 15 pizzas |
| 50 people | 19 pizzas |
You'll need 4 large pizzas for 10 people. That's based on 3 slices per person, which gives you 30 slices total. A large pizza has 8 slices, so 4 pizzas gets you to 32 slices with a couple to spare. If it's a kids' party or there are other snacks, 3 large pizzas will do it. For a more detailed breakdown by pizza type, try the calculator.
Order 8 large pizzas for 20 people. At 3 slices per person you're looking at 60 slices, and 8 large pizzas gives you 64. That little cushion matters because people go back for one more slice when there's plenty left. If your group skews toward teenagers or it's a sports team, bump it to 9 or 10. Use the calculator to adjust for your specific crowd and set up the type split.
For 30 people, you need 12 large pizzas. That's 90 slices needed and 96 delivered, so you'll have a few extras. At this size, it's worth calling your pizza place ahead of time. Most shops can handle 12 pizzas without much trouble, but give them at least an hour's notice. The calculator can help you figure out the right mix of cheese, pepperoni, and specialty pies.
You'll need 19 large pizzas for 50 people. That covers 150 slices at 3 per person, with 2 slices left over. For an order this big, call at least two hours ahead and ask about bulk pricing. Many shops will knock a few dollars off per pizza when you're ordering 15 or more. Plug 50 into the calculator to see the exact breakdown by type.
Three slices per person is a reliable default for most mixed-age groups. Kids under 12 eat 1.5 to 2 slices, adults average 2 to 3, and teenagers can put away 4 or more. If you're not sure about your crowd, use the calculator to dial in the slices-per-person number and see how it changes the total.
Standard sizes at most national chains. Your local shop may differ.
| Size | Diameter | Sq. inches | Slices |
|---|---|---|---|
| Small / Personal | 10" | 78 sq in | 4 |
| Medium | 12" | 113 sq in | 6 |
| Large | 14" | 154 sq in | 8 |
| Extra Large | 16" | 201 sq in | 10 |
A large pizza has 36% more food than a medium, even though it's only 2 inches wider. That's because pizza is a circle, and area grows with the square of the radius. Going from 12" to 14" adds 41 square inches of pizza. Going from 14" to 16" adds another 47. The bigger you go, the more food you get per inch of diameter.
Not every pizza place uses the same measurements. Domino's large is 14", but their medium is 12". Pizza Hut's large is also 14", and their medium is 12". Papa John's follows the same pattern. Little Caesars is the outlier: their standard Hot-N-Ready is 14" (large) and they don't sell a medium at all.
Local pizzerias are less predictable. Some call a 16" pizza "large" instead of "extra large." Others sell an 18" pie as their biggest option, which gives you 254 square inches per pizza. If you're ordering from a local spot for a group, ask about the diameter before you commit to a count. A shop that sells 18" pies as their large will need fewer pizzas than one selling 14" larges.
Large is the best value at most chains. A medium at $11 costs about $0.097 per square inch. A large at $14 costs about $0.091 per square inch. An XL at $17 costs about $0.084 per square inch. The bigger the pizza, the cheaper each bite. But check for deals first: chains run specials on mediums more often, and a 2-for-1 medium deal beats a single large every time. Use the calculator to compare how many of each size you'd need for your group.