How Many Pizzas for 20 People? A Chart for 10 to 100

For 20 adults, order 8 large pizzas. For 20 kids, order 5. For a mixed party of 10 adults and 10 kids, order 7. That math rests on two numbers: a large pizza is cut into 8 slices, and an adult eats about 3 slices when pizza is the meal. Kids eat closer to 2. Multiply your headcount by slices per person, divide by 8, and round up. The chart below does it for 10 to 100 guests, and the sections after it cover when you can safely order less.

The pizza chart: 10 to 100 guests

Large pizzas (14-inch, cut into 8). Adults at 3 slices each, kids at 2, and “half and half” assumes an even split of the two. Every figure is rounded up to a whole pie.

Guests	All adults	All kids	Half adults, half kids
10	4	3	4
15	6	4	5
20	8	5	7
25	10	7	8
30	12	8	10
40	15	10	13
50	19	13	16
75	29	19	24
100	38	25	32

Run your own number in one line: guests x slices each ÷ 8, rounded up. Thirty-five adults is 35 x 3 = 105 slices, ÷ 8 = 13.1, so 14 pizzas.

Where the 3-slice and 8-slice figures come from

The adult figure is the one a pizza chain uses to cater. Marco’s Pizza says on its catering page that “each large pizza includes eight slices and is ideal for three adults,” and that its party suggestions “assume about 3 slices of pizza per person.”

The kids figure is our planning number, not a chain’s. Under-sixes often stop at one slice and wander off. School-age kids at a birthday party land around two, because there is cake coming and a game to get back to. Count teenagers as adults, and count hungry teenage boys as adults and a half.

Slices are not the same size everywhere

Eight slices to a large is the common cut, but check before you order, because “a slice” moves around:

Large is 14 inches at most chains, but not all of them. If your shop’s large is 16 inches, each slice is bigger and 3 slices goes further. If its large is 12 inches, you need more pies.
Some styles are cut into fewer, bigger slices. Domino’s nutrition guide (January 2026) counts one-eighth of its 14-inch hand-tossed pizza as a serving, but one-sixth of its 14-inch New York style. Those are the chain’s serving sizes, not a cutting promise, but they tell you the New York pie is meant to be eaten in bigger pieces. If you order that style, count each slice as worth more.
Thin crust fills people less. Plan the high end, or a pie extra, if most of the order is thin crust.
Square cut helps with small kids. Many shops will cut a pie into squares if you ask. Smaller pieces mean fewer half-eaten slices left on plates, which is the same logic behind the square-cut pizza in our kids’ birthday party food ideas.

When you can order less

The chart assumes pizza is the meal. Real sides change it, and the chain’s own numbers show by how much. Marco’s suggests 3 large pizzas for 10 guests, 5 for 15 and 7 for 25. Each of those comes with breadsticks and a salad, and from 15 guests up, a 50-piece wing tray. That works out to well under 3 slices per person, because the sides are doing real work.

So drop roughly one pizza per 10 adults if you are serving any of these:

a tray of wings or a big bowl of meatballs
breadsticks or garlic knots, a full tray of them
a pasta salad or a green salad people will actually take
a dessert that lands close behind the pizza

A veggie tray and a bag of chips do not count. They get grazed at, not eaten as a course. Neither does cake at 7:30 if pizza was at 5:00.

How to split the toppings

Two out of every three pies should be the safe ones. Cheese and pepperoni go first at nearly every party, and they are what kids and picky adults will eat.

Pies in the order	Cheese	Pepperoni	Something else
4	2	1	1
8	3	3	2
12	4	4	4
20	7	7	6

Put at least one vegetarian pie in every order over six, and if anyone has a dairy or gluten allergy, ask the shop what it can do before the day, not when the delivery arrives.

Timing a big order

Call the day before for anything over ten pies. Marco’s asks for catering orders at least 24 hours ahead. Even shops that do not ask will thank you for it.
Stagger the delivery for a long party. Half at the start and half 45 minutes later means the second wave is hot when the second-helping crowd arrives.
Keep the boxes warm, not sealed. Stacked boxes in a low oven keep pizza hot without steaming it soggy. Our guide to keeping food warm for a party covers the oven-and-cooler setup.

Then watch the clock. Illinois Extension says leftover food should be refrigerated or frozen within two hours of serving, so boxes that have been on the table since lunch go in the fridge, not back out for the evening. Our guide on how to reheat pizza turns those leftovers into a crisp lunch the next day.

FAQ

How many pizzas do I need for 20 people?

For 20 adults with pizza as the main meal, order 8 large pizzas (20 x 3 slices = 60 slices, ÷ 8 = 7.5, rounded up). For 20 kids, 5 large pizzas. With real sides like wings and breadsticks, 6 or 7 pies is usually enough for adults.

How many slices of pizza per person?

Plan 3 slices of a large pizza per adult when pizza is the meal, which is the figure Marco’s Pizza uses for catering. Plan about 2 for school-age kids and 1 to 2 for preschoolers. Count teenagers as adults.

How many people does one large pizza feed?

About three adults or four kids. A large 14-inch pizza is usually cut into 8 slices, and at 3 slices per adult that is 2 to 3 people. With sides, a large stretches to about 4 adults.

How many pizzas for 50 people?

About 19 large pizzas for 50 adults, 13 for 50 kids, or 16 for an even mix. Order the day before, split the delivery into two waves, and drop a few pies if you are also serving wings or pasta.

Is it better to order large or medium pizzas for a party?

Large pizzas usually give more pizza for the order and fewer boxes to manage. Mediums make sense when you want more topping variety for a small group, since you can order several kinds without a mountain of leftovers.