About PizzaCalculator.ca
Hey, I'm Jas
Software Developer in British Columbia, Canada
This project started from a conversation at a friend's place. A group of us were trying to figure out how many pizzas to order for about 15 people, and we ended up on three different websites that all gave different answers. One said 5 pizzas, another said 8, and the third wanted me to create an account before it would tell me anything. I closed my laptop and we just guessed. We ordered 6 and ran out before dessert.
The next week I started building this calculator. As someone who writes code for a living, I figured I could put together something better. Not more complicated—just more accurate and straightforward.
I've been a software developer for several years, working mostly on web applications. This site is a side project that I maintain in my spare time, but I take the calculations seriously. Nobody wants to be the host who runs out of food.
Why This Calculator Exists
Most pizza calculators online use a single generic formula: multiply your guest count by some number and call it a day. The problem is that a kids' birthday party and an office lunch are completely different situations. A room full of teenagers will eat twice as much as a group of adults at a work meeting. Serving pizza alongside a full spread of appetizers is different from pizza being the only food available.
I wanted a calculator that accounts for these differences. This one lets you specify how many adults versus children are attending, adjust for appetite levels, and factor in whether pizza is the main course or part of a larger meal. The goal is to give you a number you can actually trust instead of a rough guess dressed up as precision.
I also added chain-specific calculations because not all pizzas are the same size. A large from Domino's has 8 slices. A large from Little Caesars has 8 slices too, but the pizza itself is a different diameter. These details matter when you're trying to feed a crowd, so the calculator adjusts based on which chain you're ordering from.
How the Math Works
The calculations are based on food service industry standards that have been used by caterers and event planners for decades. The baseline assumption is that an average adult eats about 3 slices of pizza at a meal, while children under 12 typically eat closer to 2 slices. These aren't arbitrary numbers—they come from actual consumption data collected by the restaurant industry.
From there, the calculator multiplies your guest counts by the appropriate slice amounts, divides by the number of slices per pizza (which varies by size and chain), and rounds up to the nearest whole pizza. The rounding up is intentional. You can't order three-quarters of a pizza, and showing up one pizza short is always worse than having a few slices left over.
The appetite adjustment lets you modify the baseline. Light eaters or afternoon events where people have already had lunch might only need 2 slices per person. A Super Bowl party with beer flowing might need 4. The default of 3 works for most situations, but you know your crowd better than any formula does.
What This Site Is Not
This is not a pizza ordering service. I don't take orders, process payments, or have any business relationship with pizza chains. The chain-specific calculators exist purely to give you more accurate slice counts—when you're ready to order, you go directly to Domino's or Pizza Hut or wherever you prefer.
I also don't collect personal information beyond basic analytics to understand how people use the site. There's no account creation, no email list signup requirement, and no paywalls. You come here, get your number, and leave. That's the whole point.
Get in Touch
If you have questions, found a bug, or just want to tell me about a pizza party that went well (or didn't), I'm happy to hear from you. I read every email and try to respond within a couple of days.
I'm also open to suggestions. If there's a feature you think would be useful or a pizza chain I haven't included that you'd like to see, let me know. This site gets better when people tell me what's missing.
Email: renderops.dev@gmail.com
A Note on Accuracy
No calculator can perfectly predict how much a specific group of people will eat. Human appetite varies based on dozens of factors—time of day, what else is being served, the weather, how long the event runs, whether alcohol is involved. The numbers this calculator produces are educated estimates based on reliable averages, not guarantees.
When in doubt, round up. Leftover pizza is a problem most people are happy to have.