Catering Portion Calculator
Calculates food quantities for an event by course and service style, then converts plate weights into the raw quantity you actually have to buy.
Catering Portion Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Cooking yields vary substantially with the cut, the temperature and how far the protein is cooked. A well-done roast loses considerably more than the 25% assumed for roasting.
- Service style factors are planning conventions drawn from catering practice rather than measured constants, and a particular crowd can defeat them in either direction.
- The calculator handles one course at a time. A full event needs it run per course, and the interactions between courses are not modelled.
- Trim yields depend heavily on the skill of whoever is butchering. The same joint in two kitchens can differ by ten percentage points.
In short: Plan 6–8 oz of protein, 4–5 oz of starch and 3–4 oz of vegetables per guest, and note that a buffet needs about 20% more per head than plated service because guests serve themselves. Critically, cooking loss and trim loss multiply: 6 oz on the plate can mean 9.4 oz purchased, a 57% uplift that catches out anyone who orders to plate weight.
Formula
[('standard portion', 'Cooked weight a guest receives: 6 to 8 oz protein, 4 to 5 oz starch, 3 to 4 oz vegetables, 2 to 3 oz salad.'), ('service style factor', 'Plated 1.00, family 1.15, buffet 1.20, stations 1.25, cocktail 0.75. Self-service needs more.'), ('cooking yield', 'Weight remaining after cooking. Roasting keeps about 75%, grilling 70%, braising 65%. Dry starches gain.'), ('trim yield', 'Weight remaining after butchering or peeling, as a percentage of the purchased weight.')]
Worked Example
- Fix the plate weight. Decide what each guest actually receives, in cooked ounces. This is the only figure the guest experiences.
- Apply the service style. Multiply by the style factor. A buffet needs about 20% more per head than plated service, which is the opposite of what most people assume.
- Divide by the cooking yield. To get the raw trimmed weight. Roasting costs about a quarter of the weight; braising about a third.
- Divide again by the trim yield. To get the purchase quantity. This second division is the step that gets skipped, and it is worth tens of pounds on a large event.
One hundred guests, buffet service, 6 oz of roast beef per plate. The buffet factor takes the portion to 7.2 oz, so 45 lb reaches the plates. But roasting keeps only 75% of the weight and the joint trims at 85%, and those combine to 63.8% rather than the 60% you would get by adding the losses. Working back, each plate needs 11.29 oz purchased, so the order is about 70.6 lb. Ordering to the plate weight would have left you 25 lb short — more than a third of the event.
Strengths & Limits Of This Model
Where this engine is strong
- Converts plate weights into purchase quantities, which is the number that actually appears on the invoice.
- Treats cooking and trim losses multiplicatively, avoiding the standard under-ordering error.
- Gets the direction of the buffet adjustment right, which most guidance does not.
Where it stops
- Requires a realistic trim yield, which most people have to measure once before they can trust it.
- Cannot account for the composition of the guest list, which moves consumption more than any factor here.
Practical Use Cases
Costing a wedding or private event
The purchase quantity, not the plate quantity, is what appears on the invoice and the budget.
Switching a menu from plated to buffet
The food quantity has to rise by about a fifth even though the labour falls, which is the trade-off buffet pricing has to reflect.
Offering a choice of mains
Preparing 60% of the headcount for each of two options rather than 50% is the standard insurance against an uneven split.
Working with a whole-animal or whole-fish supplier
Low trim yields make the purchase quantity far larger than the plate quantity, and the gap is where inexperienced caterers lose money.
Sanity-checking a caterer's quote
If a quote's food quantities look close to the plate weights, the caterer has either not allowed for yield or is planning to serve less than promised.
Methodology & Editorial Standards
Standard plated weights per guest are cooked ounces following common catering practice: protein 6 to 8, starch 4 to 5, vegetables 3 to 4, salad 2 to 3, bread 1.5 to 2 and dessert 3 to 4. Service style multipliers are plated 1.00, family style 1.15, buffet 1.20, stations 1.25 and cocktail reception 0.75, reflecting the greater and less consistent portions guests take when serving themselves. Cooking yields are roasting 75%, grilling 70%, braising 65%, poaching 85% and vegetables 90%, with dry starches gaining weight at 2.5 times. Trim yield is user-supplied and defaults to 85%. The purchase quantity is derived as plated weight divided by cooking yield and then by trim yield, so the two yields compound multiplicatively rather than additively. Holding temperatures follow standard food safety guidance of above 63°C for hot and below 5°C for cold, with a cumulative four hour limit between them.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Catering Portion Calculator — 9 Expert FAQs
9 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
How much food per person for catering
For a full dinner, plan 6 to 8 ounces of cooked protein, 4 to 5 ounces of starch, 3 to 4 ounces of vegetables and 2 to 3 ounces of salad per guest. On a buffet, protein typically drops to 5 or 6 ounces because guests are also loading several sides, but the total quantity of food per head rises. These are cooked, plated weights — the quantity you must purchase is considerably higher.
Do buffets need more or less food than plated service
More, by roughly 20% per head. This surprises almost everyone. Guests serving themselves take larger and far less consistent portions than a kitchen plating to a standard, and the first guests through the line are more generous than the last, which forces you to over-provision to avoid the last tables finding empty pans. Plated service is the most efficient format there is.
Why is the amount I need to buy so much more than the plate weight
Because two separate losses stack. Trimming removes bone, fat, peel and outer leaves before cooking, and cooking removes moisture and rendered fat afterwards. A 6 ounce roast beef portion at 75% cooking yield and 85% trim yield needs about 9.4 ounces purchased — a 57% uplift. Across 100 guests that is the difference between ordering 37 lb and ordering 59 lb.
Do cooking loss and trim loss add together
No, they multiply, and this is the single most expensive arithmetic error in catering. A 25% cooking loss and a 15% trim loss do not give a 40% total loss. The yields multiply: 0.75 times 0.85 is 0.6375, so 63.75% of the purchased weight reaches the plate and the real loss is 36.25%. Adding the losses understates what you need to buy, and the error grows as the losses get larger.
How much extra should I prepare beyond the guest count
Ten percent is standard insurance for a private event with a confirmed guest list. Twenty percent is prudent when the headcount is uncertain, when the crowd skews young, or when the event runs long. Weigh the two failures honestly: running out is a reputational failure guests remember for years, while surplus is a margin problem you can mitigate by choosing dishes that hold or repurpose well.
How do I plan when guests choose between two main courses
Prepare 60% of the headcount for each option rather than 50%, giving 120% of the guest count in total. Choice never splits evenly, and the shortfall always lands on whichever option turns out to be popular. For three choices, plan about 45% each. Pre-ordered choices collected in advance are the only way to avoid this overhead, and even then allow a small margin for people who change their minds at the table.
What is a safe holding temperature for catered food
Hot food above 63°C (145°F) and cold food below 5°C (41°F). Time between those limits is cumulative across the whole life of the dish and is capped at four hours in total, not four hours per service. Replenish buffets with fresh pans rather than topping up a pan that has been on the line, because topping up mixes food of different ages and resets nothing.
How much food for a cocktail reception
Canapes are not a meal, so the factor is about 0.75 of a plated portion, but the count matters more than the weight: allow 4 to 6 pieces per guest for a reception before dinner, 8 to 10 for a two-hour standing event, and 12 to 14 if the reception replaces a meal altogether. Spread those across at least five or six different items so no single canape has to carry the event.
How do I scale a recipe for 100 people
Scale the ingredients proportionally, but not the seasoning, the cooking time or the equipment assumptions. Salt and acid should be scaled and then tasted rather than trusted, thickeners often need slightly less than proportional, and the cooking vessel changes evaporation and browning substantially. Batch large quantities rather than making one enormous version of a domestic recipe.