How many pizzas for 20 people?

The 3/8 rule

Pizza math has one rule that every pizzeria uses: 3 slices per adult, 8 slices per large pizza. Twenty adults × 3 slices = 60 slices ÷ 8 = 7.5, rounded up to 8 large pizzas. Kids under 12 eat about 2 slices; teenagers and anyone arriving from practice eat 4. That's the entire calculation, and the pizza calculator does the rounding and size conversions for any mix of guests.

Pizza chart for 10 to 50 people

Adults, large 14-inch pizzas cut in 8. "Hungry" adds one slice per person (late night, after sports, teenagers); "with sides" subtracts one slice per person because wings, salad or breadsticks are also on the table.

Medium, extra-large or personal instead?

Pizza scales with the square of the diameter, so a 16-inch extra-large has about 30% more pizza than a 14-inch large, and a 12-inch medium has about 26% less. In large-slice equivalents: personal (10") ≈ 4 slices, medium ≈ 6, large = 8, extra-large ≈ 10. For 20 people that means 8 larges, or 11 mediums, or 6 extra-larges, or 15 personals. Larges and extra-larges are almost always the best price per slice — check the shop's menu, since some "large" pizzas are 16 inches and some "extra-large" are 18. If a shop cuts larges into 10 slices instead of 8, the slices are smaller and the count per person goes up; the pizza count doesn't change.

What to order for 20 people

Eight pizzas is enough to cover preferences without anyone ending up with a whole untouched pie. A safe split: 3 cheese, 3 pepperoni, 1 veggie, 1 specialty (meat lovers, BBQ chicken, Hawaiian — whatever the crowd is). Cheese and pepperoni always go first; the specialty pie is the one you can afford to have leftovers of. For a group with kids, tilt further toward cheese. Ask for pies uncut or half-and-half if you want more variety without more pizzas, and order 15 minutes before you actually want to eat — most shops quote 30–45 minutes for an 8-pizza order and hit it.

Side dishes that change the count

If wings, salad, garlic knots or dessert are on the table, most people drop from 3 slices to 2 — that's the "with sides" column, and it takes 20 people from 8 pizzas to 5. Standard pairings: for 20 people, 100 wings as a side (about 11 lb) or 200 as a co-main; a family-size salad serves 8, so order 2–3; garlic knots at 2 per person. Drinks: about 2 per person for the first hour, 1 per hour after — for 20 people over 3 hours, 80 cans or 12 two-liter bottles. The wings calculator and drink calculator size those.

Leftovers and reheating

Rounding up from 7.5 to 8 pizzas leaves a few slices — good. A party where the last pizza box is empty is a party where somebody didn't get enough. Leftover pizza keeps 3–4 days in the fridge and reheats best in a skillet with a lid or a 375°F oven, not the microwave.

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Frequently asked questions

Sources

• Instacart: pizza calculator and the 3/8 rule
• Green Lantern Pizza: how many pizzas do you need