Which calculator for which situation
- Barbecue. Barbecue calculates meat, charcoal and drinks by guest profile — adults, children, and who drinks and who does not.
- Party. Party food and party drinks size the catering, soft drinks and ice; cost per guest closes the budget and splits it.
- Pizza. Pizza answers how many and what size — with the maths almost everyone gets wrong.
The pizza calculation nobody runs
Two 12-inch pizzas feel like more than one 16-inch. They are less.
Area is π·r², so it grows with the square of the diameter. Two 12-inch pizzas total about 226 square inches; one 16-inch has 201 — close, with the two mediums just ahead. But compare a 16-inch against a 12-inch: 201 against 113 square inches, nearly double, for a price that is rarely double.
The practical rule: compare price per square inch, never price per pizza. On most menus the large is the cheapest by area, and the gap frequently exceeds 30%.
How much to buy: margins that work
Sizing an event is estimation with margin, and some patterns repeat:
- Meat: around 12 to 14 oz per adult for a barbecue lasting a few hours, less with plenty of sides, more if the grill is the only food.
- Drinks: consumption scales with duration and heat, not with guest count alone. The first hour consumes considerably more than the ones that follow.
- Ice: the most underestimated quantity at any party. Plan for far more than seems necessary, and remember it melts before it is used.
- Appetisers: events with a served meal consume fewer; cocktail-only events, many more.
It is always worth rounding up on drinks, ice and bread, and staying tight on protein — leftover meat is expensive, leftover ice costs almost nothing.
Frequently asked questions
How do I count children? The usual convention is half a portion for children under ten, though drink consumption tends to be proportionally higher — soft drinks run out first.
What if I do not know the headcount? Size by confirmed guests plus a margin: for informal events, around 10% usually covers it. Buy protein for the confirmed count and drinks for the confirmed count plus margin — drinks keep, meat does not.
How should the cost be split? The cost-per-guest calculator divides the total, but agree the model beforehand: even splits when consumption is similar, proportional when some people are not drinking. Deciding afterwards is the source of all the awkwardness.
How far ahead should I buy? Drinks and non-perishables early, without rushing on price. Meat and perishables as close as possible — buying early rarely saves enough to justify the risk.