What this calculator does
Ordering pizza for a group comes down to three numbers: how many people are eating, how many slices each of them typically eats, and how many slices come on the pizzas you are ordering. Multiply the first two, divide by the third, and round up, because nobody sells a fraction of a pizza.
The mistake people make is assuming a fixed rule like "one pizza per three people" and applying it to every event. A lunch crowd eats less than a dinner crowd, a large pizza cuts into more slices than a personal one, and a group with kids eats differently to a group of adults. Treating slices-per-person and slices-per-pizza as adjustable inputs, rather than a fixed ratio, gets a more reliable number for the specific event being planned.
The formula
Multiply the number of guests by the slices each is expected to eat, giving the total slices needed. Divide that by the number of slices per pizza, then round up to the next whole pizza, since a partial pizza still has to be ordered as a whole one.
| Term | Meaning |
|---|---|
| Slices per person | An estimate of appetite, typically 2 to 4 slices depending on the meal and the crowd. |
| Slices per pizza | How many slices one pizza is cut into, which varies by size and by pizzeria, commonly 6 to 10. |
| Pizzas to order | The total slices needed divided by slices per pizza, rounded up to a whole number. |
The inputs explained
| Field | What to enter |
|---|---|
| Number of guests | The number of people expected to eat pizza. |
| Slices per person | How many slices you expect each guest to eat. Adjust up for a dinner crowd, down for a lunch crowd or a mixed buffet. |
| Slices per pizza | How many slices each pizza is cut into at the size you plan to order. |
When to use it
Catering an office lunch or party
Working out pizzas for 50 people, or any headcount, ahead of an event avoids both an awkward shortfall and paying for pizzas that go straight in the bin.
Adjusting for a mixed crowd
A group with children or a lighter meal setting can be given a lower slices-per-person figure than a crowd of hungry adults at dinner, without changing the rest of the calculation.
Comparing pizza sizes before ordering
Changing slices per pizza to match a large versus an extra-large size shows how many fewer pizzas are needed for the same group, which is useful when a menu prices sizes differently.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How many pizzas for 50 people at different appetite levels
The same 50-person group, at a range of slices-per-person assumptions.
| Slices per person | Pizzas to order | Total slices needed | Slices left over |
|---|---|---|---|
| 2 slices | 13 | 100.0 | 4.0 |
| 2.5 slices | 16 | 125.0 | 3.0 |
| 3 slices | 19 | 150.0 | 2.0 |
| 3.5 slices | 22 | 175.0 | 1.0 |
| 4 slices | 25 | 200.0 | 0.0 |
How pizzas needed scale with guest count
A fixed appetite of 3 slices per person, across a range of group sizes.
Questions
How many pizzas for 50 people?
At a common estimate of 3 slices per person and pizzas cut into 8 slices, 50 people need 19 pizzas. Adjust slices per person for the meal type and slices per pizza for the size you are ordering, since both change the answer.
Why does the calculator round up instead of to the nearest whole number?
Pizzas are ordered as whole units, so rounding down would leave the group short of slices. Rounding up guarantees enough pizza, at the cost of a few leftover slices in most cases.
How many slices should I assume per person?
Two to three slices suits a lunch or a buffet with other food available; three to four suits a dinner where pizza is the main meal. Children typically eat less than adults, which is worth factoring in for a mixed group.
Should I order a mix of pizza sizes instead of one size?
This calculator assumes one slice count per pizza, so run it once per size you plan to order and add the results together, or use a weighted average slices-per-pizza figure if the mix is roughly fixed.
For working out drinks alongside the food, see the alcohol for a party calculator. For a similar per-person estimate with meat instead of pizza, see the meat per person for a BBQ calculator.