For a party, plan about 300 to 400 grams of food per person if the buffet replaces dinner, and 150 to 200 grams if it is only a snack before or after a meal. For drinks, count around 1 litre of water and soft drinks per person over an evening, and half a bottle of wine for each adult who drinks wine. These are starting points, not laws: the guests, the time of day and how long the party lasts change the numbers. Here is how to calculate the shopping list without running out or throwing half of it away.
How much food per person for a buffet?
The first question is whether the party is a meal or not. A buffet at dinner time, from 7 or 8 in the evening, replaces dinner: guests arrive hungry and eat 300 to 400 grams each in total. An afternoon party or one after dinner needs about half, 150 to 200 grams per person. Children usually eat half of what adults eat.
A practical way to split the total is by category. For a dinner buffet for 10 adults, about 3.5 kg of food, think of roughly one third savoury bakes and sandwiches, one third cold dishes such as pasta salad, rice salad or cured meats and cheese, and the rest vegetables, dips and bread. If you serve a hot pasta dish, count 80 to 100 grams of dry pasta per person, as for a normal meal.
How much to drink per guest?
Count around 1 litre of non alcoholic drinks per person for an evening of four hours, more in summer or if people dance. At least half of it should be water, still and sparkling. For alcohol, a common rule is half a bottle of wine, 375 ml, for each adult who drinks wine, or two to three bottles of beer of 33 cl for each beer drinker. Ask a few guests what they prefer: a group of friends who only drink beer will leave every bottle of wine closed.
How much ice do you need?
About half a kilo of ice per person, more if the party is outdoors in summer or if you serve cocktails. Ice melts faster than expected, so buy it last, on the day, and keep it in a cool box. It is one of the items most often forgotten, because nobody puts it on the list until it is needed.
How big a cake for a birthday?
Count one slice of 100 to 120 grams per person. A round cake of 24 centimetres gives 10 to 12 slices, one of 28 centimetres about 16. If there are other desserts, you can reduce the slices slightly. For a children's party, smaller slices are fine.
What about plates, cups and the things nobody thinks of?
Plan two cups per guest, because cups get put down and lost. One and a half plates per person, and enough napkins for three each. Then the list of things that are always missing at the last minute: bin bags, kitchen roll, a bottle opener, candles and matches for the cake, a knife for cutting it, cling film for the leftovers. Writing them at the bottom of the list once saves an evening trip to the shop.
How do you avoid buying too much?
Add a margin of about 10% to your totals, not more. Parties end with leftovers mostly because each guest also brings something. If friends offer to bring food or drinks, agree on what they bring and write it down next to their name, so that you do not buy the same things. Prefer products that keep if they are not opened: bottled drinks, crisps, tins, cured meats in sealed packs.
How do you organise the shopping with the other organisers?
When more people share the shopping for a party, the risk is five bottles of wine and no ice. A shared list just for the event solves it: you write every product with its quantity, "ice 5 kg", "cups 40", and whoever buys something ticks it off so the others see it. With Paniere you can create a separate list for the party, invite only the organisers and delete it when the party is over. For the daily shopping after the party, there is always what you already have at home.