How much spare food should I make?

It depends far more on the size of the group than on anything else. For a small gathering the margin needs to be generous, because one hungry guest is a big fraction of the total — around fourteen percent for eight people to be reasonably confident. For a hundred guests, four percent covers the same risk, because individual variation averages out across a crowd. Most guidance quotes a single figure like ten percent, which is too little for a dinner party and too much for a wedding.

Why does a bigger event need proportionally less spare food?

Because of how variation behaves when you add things up. Each guest brings the same uncertainty, but those uncertainties partly cancel — someone eating more is offset by someone eating less. Mathematically the spread of a total grows with the square root of the count while the total itself grows with the count, so the ratio between them shrinks. Doubling the guest list only multiplies the uncertainty by about 1.41, not by two, and the margin as a share falls accordingly.

If I serve three main dishes, do I need three times the food?

No, and not far off a third of the way there. People eat to fullness rather than to a set weight of any particular thing, so offering more choices splits the same appetite. Published guidance puts a single protein at about half a pound per head, falling to roughly a third of a pound each when several are on offer. The total does rise, because variety tempts people into eating a bit more, but three dishes costs you nearer one and a half times the food than three times it.

How much more do I need for a buffet than a plated meal?

Around ten to twenty percent overall, and rather less than the raw serving figures suggest. Published protein amounts jump from 110 to 170g plated up to 170 to 225g for a buffet, which looks like a huge increase — but the upper end of that range describes a barbecue, where the meat is the whole occasion. At a general buffet the total moves by about fifteen percent and the composition shifts, because a guest who piles on the potatoes takes less of everything else.

What is a standard portion of meat per person?

Published catering guidance settles on 110 to 170g of cooked meat for a plated meal — four to six ounces — with 170 to 225g for a buffet or barbecue. Vegetarian mains come in around 175g of cooked food. Those are cooked weights, which matters: buying that much raw will leave you short, because trimming and cooking both take their share. A rough doubling is common for a fatty cut cooked long, though the honest figure depends on the cut.

Are these raw or cooked weights?

Cooked, and on the plate. Turning them into a shopping list needs two more steps: trimming loss, which is what you throw away before cooking, and cooking loss, which is water and fat leaving the pan. Both compound, so a cut yielding 70% after trimming and 61% after cooking gives only 43% of what you bought. The yield calculator handles that conversion; this page stops at the plate deliberately, because mixing the two is where most over-ordering and under-ordering starts.

How do I account for children or big eaters?

Count children as roughly half an adult for planning and adjust from there by age — teenagers frequently eat more than adults do. For a group with a known skew, the honest move is to change the per-head figure rather than to inflate the margin, because the margin is there to cover randomness and a rugby team is not random. The published anchors are averages across catered events; if you know your guests, your knowledge beats the average.

Does the length of the event change how much I need?

Yes, and more than people allow for. Guidance suggests adding fifteen to twenty percent for anything running past two hours, because people go back. Serving alcohol adds roughly another ten percent — that is documented behaviour rather than folklore. A short drop-in event needs considerably less than the same headcount sitting down for an afternoon. Adjust the per-head figure for these rather than the statistical margin, which is measuring something different.

What if I would rather have leftovers than run short?

Then say so explicitly rather than quietly inflating everything. Pushing the confidence to ninety-five percent raises the margin in a way that is proportionate and visible — and for a small group that is a meaningful jump, from around fourteen to eighteen percent at eight guests. The alternative, adding an arbitrary half again to every dish, tends to produce a great deal of one thing and not enough of another, because the uncertainty was never evenly spread to begin with.

How reliable is the thirty percent appetite variation?

It is a reasonable default rather than a measurement, and it is the input the answer is most sensitive to — the margin scales directly with it. A group of similar people eating a familiar meal varies less; a mixed crowd at an unfamiliar buffet varies more. If you have catered for the same group before, the useful thing is not a better formula but a record of what actually came back, and that record beats any published figure including this one.

Recipe Portion Size Calculator

Cooking for a crowd has one question at its centre and it is not how much a person eats. It is how much spare you need so that nobody goes without — and the answer is stranger than it looks. Appetites vary. Some people eat half again what others do. But across a group the large and the small cancel...

These are planning quantities for feeding a group — how much to cook so nobody goes without — and they are cooked weights. Turning that into a shopping list means allowing for trim and cooking loss, which the yield calculator handles. Nothing here is a statement about what any individual should eat; people differ, and the numbers below are averages for planning against.

THE TABLE

GUESTS

DISHES OF THIS KIND

OR SET YOUR OWN PER-HEAD FIGURE (G)

HOW SURE DO YOU WANT TO BE

APPETITE VARIATION (%)

COOK THIS MUCH PROTEIN

3.04 kg

140 g a head for 20 people, plus 8.6% spare to be 90% confident nobody goes without. These are cooked weights.

PER HEAD

140 g

BASE

2.80 kg

SPARE

8.6%

The bigger the group, the smaller the margin you need — proportionally. Individual appetites vary, but across a crowd the big eaters and the small ones cancel out, and the total becomes more predictable than any one plate. At 90% confidence and 30% variation, eight guests need 13.6% spare while a hundred need only 3.8%. It is why caterers can run tighter than a dinner party host, and it is the reverse of what most people assume.

Guests	Spare needed	Base	Cook
4	19.2%	560 g	668 g
8	13.6%	1.12 kg	1.27 kg
20	8.6%	2.80 kg	3.04 kg
50	5.4%	7.00 kg	7.38 kg
100	3.8%	14.00 kg	14.54 kg

What the arithmetic cannot see. It assumes your guests are a random draw from an average crowd, which they are not — a rugby team and a book group differ more than any statistical margin covers, and children, the time of day, how long the event runs and whether drink is served all shift the figure. The published anchors are averages across catered events, so treat them as a starting point and adjust for who is actually coming. If in doubt with a small group, cook more: the arithmetic says that is exactly where the risk sits.

THE MARGIN

The curve falls with the square root of the guest count. Appetites vary by the same amount per person however many there are, but the variation of the total grows more slowly than the total itself — so the spare capacity you need, expressed as a share, shrinks. Four guests is the risky case, not four hundred.

Live calculation · updates as you type

Created with❤️byeaglecalculator.com

HOW TO USE

1
Enter the guest count and pick the kind of dish. The anchors come from published catering guidance and you can overwrite any of them with a figure you trust more.
2
Say how many dishes of that kind you are offering. Two mains does not mean twice the food — the calculator splits the appetite rather than multiplying it.
3
Choose how confident you want to be. Eighty percent is a relaxed family lunch; ninety-five is a paid event where running out is not an option.
4
Read the spare percentage against the guest count. If you are cooking for a small group, that number will be larger than you expect, and it is the honest answer.

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Last updated: August 1, 2026 · Anchors from published catering guidance · Cooked weights · Planning quantities for a group, not guidance on individual intake.