To work out how much food to make for a buffet, multiply each dish's grams per guest by the number of guests, then add the overproduction percentage you choose. The grams per guest do not come from a table. They come from your usual portion, adjusted because buffet guests take a little of several dishes, and corrected event after event by weighing what was left. The figures in this article are examples to show the method, not a rule.
Where your grams per guest come from
Start with what you already know. If you serve 120 g of roast potatoes on a plated meal, that is a starting point for potatoes. Then think about the event:
- How many options there are. With two mains, hardly anyone takes a full portion of each. Each main needs less than it would alone, but the two together need a bit more than one.
- Time of day and type of event. A working lunch is eaten differently from a party that runs all afternoon.
- Who serves. If your staff serve, you control the portion. If it is self-service, people help themselves, and that changes what runs out first.
- Your records. What you weighed as leftovers at similar events is the best information you have.
Keep your grams per guest for each dish on one sheet and review them after every event. The guide on portion control helps keep your reference portion consistent.
The sum
For each dish:
cooked amount = grams per guest × guests × (1 + overproduction)
And to know what to buy, go from cooked to raw with your own yield:
raw amount = cooked amount ÷ yield
The yield is what you measured: if 1 kg of raw chicken thigh gives you 750 g once roasted, your yield is 0.75. The real cost per usable kg tool handles this conversion for any ingredient.
Worked example: a lunch buffet for 60 guests
A company anniversary lunch for 60. Menu: roast chicken thighs, vegetable lasagne, roast potatoes, green salad and bread rolls. The grams per guest come from this caterer's own sheet, built from past events. They choose 10% overproduction.
| Dish | g per guest (their number) | × 60 | With 10% extra |
|---|---|---|---|
| Roast chicken thighs | 120 g | 7,200 g | 7,920 g |
| Vegetable lasagne | 150 g | 9,000 g | 9,900 g |
| Roast potatoes | 120 g | 7,200 g | 7,920 g |
| Green salad | 60 g | 3,600 g | 3,960 g |
| Total | 450 g | 27,000 g | 29,700 g |
| Bread rolls | 1 each | 60 | 66 |
Look at the total: 450 g per guest before the extra, plus a roll. Compare it with what you know from similar events. If, in your experience, people eat clearly more or less, go back through dish by dish before you shop.
From cooked to raw, with their own measurements:
- Chicken: if 1 kg raw gives 750 g roasted, 7,920 ÷ 0.75 = 10,560 g. Buy about 10.6 kg.
- Potatoes: if 1 kg raw gives 800 g once peeled and roasted, 7,920 ÷ 0.80 = 9,900 g. Buy 10 kg.
- Lasagne: one of their trays yields 3.2 kg. Three trays give 9,600 g. That covers the 9,000 g plus 600 g, a 6.7% extra instead of 10%. They decide that is enough for this dish rather than baking a fourth tray.
To get ingredient quantities for a recipe written for a different batch size, the tool that scales a recipe to N portions does it for you.
Leftovers: the number you are missing
After the event, before anything is packed up or handed out, weigh what is left of each dish. Here: 0.5 kg of chicken, 1.9 kg of lasagne and 1.4 kg of potatoes.
| Dish | Made | Left | Eaten per guest |
|---|---|---|---|
| Chicken | 7,920 g | 500 g | (7,920 − 500) ÷ 60 = 124 g |
| Lasagne | 9,600 g | 1,900 g | (9,600 − 1,900) ÷ 60 = 128 g |
| Potatoes | 7,920 g | 1,400 g | (7,920 − 1,400) ÷ 60 = 109 g |
Three readings:
- Chicken: guests ate 124 g, more than the 120 g on the sheet. It nearly ran out. Next time, raise it.
- Lasagne: 128 g eaten against 150 g planned. Lower it.
- Potatoes: 109 g eaten against 120 g planned. Some left, but it is the cheapest dish.
What the leftovers cost
Using the cost per kilo of each dish from your recipes:
- Lasagne: 1.9 kg × $9.50 a kilo = $18.05
- Chicken: 0.5 kg × $14.00 a cooked kilo = $7.00
- Potatoes: 1.4 kg × $1.40 a roasted kilo = $1.96
- Total: $27.01
Two thirds of the leftover money is lasagne (18.05 ÷ 27.01 = 67%). The lesson is not "cook less" but where to put the extra. If you want to be sure nobody goes without, put it on potatoes, rice or bread, which cost little, and keep the expensive dishes close to what your records say people eat. The guide to the cost of food waste shows how to keep this record week to week.
The extra belongs in the quote
Overproduction is not a gift: it is food you buy and cook, and it has to be in the price. When you build your per-person quote, add the overproduction percentage to the food cost per guest. If canapés go round before the buffet, cost them separately, as in the guide to pricing finger food by the piece, and trim the starters.
Do it with the calculator
Put each recipe into the food cost calculator with your grams per guest as the portion; you get the cost per guest of every dish and can see what each point of overproduction costs you.
Frequently asked questions
Is there a standard amount of food per person?
There is no number that fits every event. It depends on the menu, the time of day, the crowd and how the food is served. Start from your plated portion, adjust for how many options there are, and correct it with what is left after each event.
How much extra should I cook?
A percentage you set and refine with your own records. If nothing is ever left, you are cutting it too fine; if the same dish is always left over, you are throwing money away on it.
Should the extra go on every dish equally?
It does not have to. A bit more rice or potatoes costs little and makes sure nobody goes hungry. A big margin on the meat is expensive when it comes back.
What should I do with leftovers?
Weigh them and write it down first, before deciding whether they go to the client, the staff or tomorrow's menu. That weight is the figure that improves your next quote.