How do I calculate the serving size of a recipe?

Weigh the finished dish (weigh the empty pan first and subtract it), then divide by the number of servings: serving size = total finished weight ÷ servings. A 2,400 g lasagna cut into 8 pieces is 300 g (10.6 oz) per serving. Weigh after cooking, because cooking changes weight through water loss or absorption.

How do I calculate calories per serving?

Add up the calories of every ingredient to get the recipe total, then divide by the number of servings. The same applies to protein, carbohydrate and fat. A 3,200 kcal recipe divided into 8 servings is 400 kcal per serving, as long as each serving weighs the same.

How many servings does my recipe make?

Divide the finished weight by the serving size you want: servings = total weight ÷ serving size. 2,400 g of chili at 350 g per bowl makes 6.9, so about 7 servings.

How much food per person for a party?

For a dinner with average appetites this calculator uses 6 oz (170 g) of cooked main protein, 4 oz each of starch and vegetables, 3 oz of salad, 1.5 oz of bread and 4 oz of dessert per person, plus about 20 fl oz of non-alcoholic drinks. Lunch, appetizer, buffet and appetite settings scale these amounts.

How many appetizers and drinks per person for a cocktail party?

A common planning rule is about 6 bites per person in the first hour and 4 in each later hour, and 2 drinks per person in the first hour plus 1 per hour after that. A 3-hour party for 40 guests needs about 560 bites and 160 drinks.

How much raw meat should I buy?

Meat typically loses about a quarter of its weight in cooking, so this calculator lists the raw weight to buy as cooked weight ÷ 0.75. 6 oz cooked is about 8 oz raw per person. Bone-in cuts need more.

Are these quantities exact?

No. They are planning estimates based on common catering guidelines. Consumption varies with the crowd, time of day, event length and how many dishes are served. Add 5–10% as a buffer.

Serving Size Calculator

Recipe mode: serving size = finished recipe weight ÷ number of servings, plus calories and macros per serving. Party mode: per-person and total quantities of protein, sides, dessert and drinks for any guest count, in US or metric units.

Number of guests

Meal type

Appetite level

Units

Recipe serving size

Enter the finished amount and the number of servings.

Serving size

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Net recipe amount

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Nutrient	Recipe total	Per serving

Enter your event details and click Calculate

Shopping list

Category	Per person	Total for event

How much food per person: dinner quantities by guest count

Average appetite, plated or family-style dinner. Lunch is about 15–25% less; a buffet is about 20% more.

Food	Per person	10 guests	25 guests	50 guests	100 guests
Main protein (cooked)	6 oz (170 g)	3.8 lb	9.4 lb	18.8 lb	37.5 lb
Side starch	4 oz (113 g)	2.5 lb	6.3 lb	12.5 lb	25 lb
Vegetables	4 oz (113 g)	2.5 lb	6.3 lb	12.5 lb	25 lb
Salad / greens	3 oz (85 g)	1.9 lb	4.7 lb	9.4 lb	18.8 lb
Bread / rolls	1.5 oz (43 g)	0.9 lb	2.3 lb	4.7 lb	9.4 lb
Dessert	4 oz (113 g)	2.5 lb	6.3 lb	12.5 lb	25 lb
Non-alcoholic drinks	20 fl oz (591 mL)	1.6 gal	3.9 gal	7.8 gal	15.6 gal

How to calculate serving size

Serving size = (finished weight − pan weight) ÷ number of servings.
Number of servings = net finished weight ÷ desired serving size.
Per-serving nutrition = recipe total ÷ number of servings (calories, protein, carbs, fat).
Scale factor = target yield ÷ original yield; multiply every ingredient by it.

Worked example: a lasagna and its pan weigh 3,400 g; the empty pan weighs 1,000 g, so the lasagna is 2,400 g. Cut into 8 pieces, each serving is 2,400 ÷ 8 = 300 g (10.6 oz). If the ingredients total 3,200 kcal and 192 g of protein, each serving has 400 kcal and 24 g of protein. Weigh after cooking: pasta and rice gain water, while roasts and baked goods lose it.

Recipe serving sizes are your own portions. The serving size printed on a US Nutrition Facts label is different: it is set from FDA reference amounts customarily consumed (21 CFR 101.12) and is not a recommendation of how much to eat.

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Summary

How it works

Choose Recipe serving size or Party food quantities.
Recipe: weigh the finished dish (subtract the pan weight), enter the number of servings, and read the serving size in grams and ounces. Add total calories and macros to get them per serving.
To find how many servings a dish makes, switch to "Servings from a serving size" and enter the portion you want.
Party: enter guests, meal type and appetite (and event length for a cocktail party), choose US or metric units, then press Calculate.
Copy the shopping list, and add 5–10% for unexpected guests.

Use cases

Work out grams per serving for a casserole, soup or meal-prep batch so every container is equal.
Calculate calories per serving for a homemade recipe from the total of its ingredients.
Plan how much chicken, sides and drinks to buy for a 50-person dinner or a 100-guest cocktail reception.
Scale a recipe from 6 servings to 40 for a family reunion.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu