What is a pizza calculator?
A pizza calculator tells you how many pizzas to order so everyone in your group gets enough to eat. Instead of guessing and ending up with too little food or a fridge full of leftovers, you enter how many people are coming, how hungry they are, and how many slices each pizza is cut into. The calculator does the arithmetic and rounds up to a whole number of pizzas, because you can only order whole pizzas.
Formula
First find the total number of slices the group needs, then divide by the slices in one pizza and round up:
The ceiling brackets mean “round up to the next whole number”, so a result of 3.75 pizzas becomes 4.
How to use
- Enter the number of people you are feeding.
- Set the slices per person — a common rule of thumb is 3 slices for an average adult, fewer for children, more for a hungry crowd.
- Set the slices per pizza — large pizzas are often cut into 8, while smaller ones may have 6.
- Read off the total slices needed and the pizzas to order.
Worked example
Suppose 10 people are coming, each is expected to eat 3 slices, and every pizza is cut into 8 slices.
- Total slices = 10 × 3 = 30 slices
- Pizzas = ⌈30 ÷ 8⌉ = ⌈3.75⌉ = 4 pizzas
So you should order 4 pizzas, which gives 32 slices and a small buffer of 2 spare slices.
FAQ
How many slices should I assume per person? Three slices per adult is a reasonable default for a casual meal. Increase it to 4 for big eaters or a dinner where pizza is the only dish, and lower it to 1–2 for children or when there are plenty of sides.
Why does the result round up instead of down? You can only buy whole pizzas, and ordering down would leave some people short. Rounding up guarantees there are enough slices for everyone, usually with a few to spare. If you want to budget more tightly, see the tip calculator and discount calculator to plan the rest of your order.