Portion Size Calculator
Understanding standard portion sizes is fundamental to meal planning, cooking for groups, and following dietary guidelines. The USDA MyPlate system, based on the Dietary Guidelines for Americans, defines standard serving sizes for five food groups: protein foods, grains, vegetables, fruits, and dairy. For protein foods, one serving is 1 ounce-equivalent (approximately 28 grams of cooked lean meat, poultry, or seafood). For cooked grains, one serving is 1/2 cup. For vegetables, one serving is 1 cup raw or 1/2 cup cooked. For fruit, one serving is 1 cup. For dairy, one serving is 1 cup of milk, yoghurt, or fortified soy beverage. This calculator takes your food type, the number of servings per person, and the number of people you are feeding. It outputs the total quantity needed in grams, ounces, and cups, making it easy to scale for any group size from a single person to a large gathering.
USDA MyPlate serving size reference
| Food group | One serving | Weight (g) | Visual guide |
|---|---|---|---|
| Protein (meat/poultry/fish) | 1 oz cooked | 28 g | Size of a large egg |
| Protein (egg) | 1 large egg | 50 g | 1 egg |
| Grains (cooked) | 1/2 cup | 92 g | Half a baseball |
| Grains (bread) | 1 slice (1 oz) | 28 g | 1 standard slice |
| Vegetables (raw) | 1 cup | 85 to 150 g | Size of a baseball |
| Vegetables (cooked) | 1/2 cup | 85 to 100 g | Half a baseball |
| Fruit | 1 cup | 150 g | Size of a baseball |
| Dairy (milk / yoghurt) | 1 cup (8 fl oz) | 245 g | Standard measuring cup |
| Dairy (cheese) | 1.5 oz (hard cheese) | 42 g | 4 stacked dice |
Portion sizes: frequently asked questions
What is a USDA MyPlate serving size?
The USDA MyPlate guidelines define standard serving sizes for each food group. A protein serving is 1 ounce-equivalent (approximately 28 grams): 1 oz cooked lean meat, poultry, or seafood; 1 egg; 1/4 cup cooked beans or peas; 1 tablespoon peanut butter; 1/2 ounce nuts or seeds. A grain serving is 1 ounce-equivalent. A vegetable serving is 1 cup raw or 1/2 cup cooked. A dairy serving is 1 cup. These are official definitions from the USDA Dietary Guidelines.
How many servings of protein do adults need per day?
The USDA Dietary Guidelines for Americans 2020-2025 recommend protein intake based on age and sex. Adults generally need 5 to 7 ounce-equivalents of protein foods per day. A sedentary adult woman typically needs 5 oz-eq; a moderately active adult man needs 6.5 oz-eq. Athletes and very active individuals may need more. The USDA MyPlate website has personalised recommendations based on age, sex, and activity level.
What counts as a cup of vegetables?
According to the USDA, 1 cup of vegetables equals: 1 cup of raw leafy vegetables (approximately 85 grams); 1 cup of other raw or cooked vegetables; 1/2 cup of cooked leafy vegetables; or 1 cup of vegetable juice. One cup is the standard MyPlate vegetable serving unit. Adults need 2 to 3 cups of vegetables per day depending on calorie needs.
How large is a standard protein portion?
A common visual guide for a 3-ounce (85-gram) cooked protein serving is the size of a standard deck of playing cards, or the palm of an average adult hand. Restaurant portions are frequently much larger: a typical restaurant steak is 6 to 12 ounces, which represents 2 to 4 MyPlate protein servings. The USDA guidelines are for planning daily intake, not restaurant meals.
What is the difference between a portion and a serving?
A serving is a standardised unit defined by the USDA or other food authorities. A portion is the amount of food you actually eat at one sitting, which may be larger or smaller than a serving. Many packaged foods contain multiple servings per container. The USDA MyPlate guidelines use serving sizes to help people plan a balanced diet across all food groups.
References
- USDA MyPlate: What is MyPlate?
- Dietary Guidelines for Americans 2020-2025: dietaryguidelines.gov.
- USDA Agricultural Research Service: FoodData Central.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Serving sizes are USDA MyPlate standard definitions. Individual dietary needs vary. See our methodology.