Begin With a Working Number, Not a Wishful One

Every good catering estimate starts with a number you can actually defend. That is rarely the number of invitations you sent. For a daytime wedding, expect between 80 and 90 per cent of invited guests to attend; for an evening reception where you have invited colleagues and distant friends, plan on closer to 60 or 70 per cent. Corporate events behave differently again — a midweek lunch will usually hold its numbers, while a Friday evening drinks reception can quietly gain a dozen people as partners and colleagues drift in.

Then add your buffer. A working figure of invited guests minus 15 per cent, plus 10 per cent gives you a catering number that absorbs the plus-one who never replied, the colleague who brought a friend, and the guest who has been training for a marathon and eats like it. Write that number down and use it for every calculation that follows.

Let the Style of Service Set Your Baseline

The same 120 guests will eat wildly different amounts depending on how the food is served. Seated service means controlled portions; a help-yourself buffet means generous scoops and second visits. Use these as your starting points:

• Canapé reception: allow 4 to 5 pieces per guest for the first hour, then 3 per hour after that. A two-hour drinks reception needs roughly 8 to 10 pieces per person, and 12 if it runs into a third hour or replaces a meal.
• Seated three-course meal: one serving of each course per guest, plus a 10 per cent buffer. Guests rarely take more than one dessert, so this is your most predictable format.
• Buffet: assume every guest takes 1.5 servings of the main and helps themselves twice to sides. This is where under-catering happens most often.
• Afternoon tea: 3 to 4 finger sandwiches per person, 2 scones, and 2 to 3 small cakes. Guests eat more sandwiches and fewer cakes than hosts expect.
• Hog roast or barbecue: 250g of cooked meat per person for a mixed crowd, dropping to 200g if you are also serving a substantial vegetarian main.

Practical Portions: What to Allow Per Guest

These weights are cooked or prepared weights, and they are worth memorising. For a plated main course, allow 200 to 250g of protein — chicken, beef, fish or a vegetarian equivalent. If you are offering two meats, 150g of each is plenty and guests will take less of the second. For a buffet, push the protein to 250g per person and remember that a joint loses roughly 35 per cent of its weight during roasting, so a 5kg raw leg of lamb serves around 12 to 14 people generously.

Sides follow a comfortable pattern:

• Potatoes: 200g per person, or 250g if they are the only starch.
• Rice or couscous: 80g dry weight per person.
• Salads and vegetables: 75 to 100g per person, and closer to 125g for a buffet.
• Bread: 2 to 3 slices or rolls per person at a buffet, 1 at a seated meal.
• Cheese board: 80 to 100g per person across all cheeses, with 60g of biscuits.

Children under ten eat roughly half an adult portion, and under-fives often eat almost nothing at all. Do not let a handful of toddlers inflate your order.

Drinks Are Where Budgets Quietly Disappear

Alcohol is the hardest line to predict and the easiest to overspend on. A reliable rule for a reception is two drinks per person in the first hour, then one per hour afterwards. A four-hour celebration therefore needs about five drinks per adult guest.

For wine at a meal, work on half a bottle per person, or one bottle between two. A 75cl bottle gives you six 125ml glasses, so a table of eight needs four bottles to see them comfortably through the main course. Sparkling wine pours six flutes per bottle at a modest 125ml. For soft drinks, allow three to four servings per person across an evening, and remember that non-drinkers drink more of them. Tea and coffee at the end of the night: one cup per guest, plus 20 per cent, and always brew in smaller batches so the last cups are not stewed.

Timing, Buffer and the 15 Per Cent Rule

Long gaps between courses make guests hungrier; arriving food late to a room that has been drinking for two hours is a recipe for empty trays. Keep canapés circulating within 20 minutes of arrival, and if the meal is delayed by more than 30 minutes, put out extra bread, olives or bowls of crisps. Late-night food is often over-ordered and under-eaten — if you have 100 day guests, plan for 60 to 70 portions of bacon rolls or chips, not 100.

Finally, apply your buffet buffer honestly:

• 10 per cent on seated, portion-controlled meals.
• 15 to 20 per cent on buffets and self-service.
• 25 per cent for barbecues, family gatherings with children, or any event with a long drinks reception beforehand.
• Add one or two extra vegetarian and vegan portions beyond the guests who request them, and cater for dietary requirements at roughly 12 per cent of the total to cover the people who mention it on the day.

Then feed your own team. A portion set aside for staff at the end of service is not waste — it is the difference between a cheerful team and one that runs out of energy by pudding. A little leftover food is a sign of good hospitality; too much is a sign of guesswork. Aim for slightly generous, never scrambling.