Portion Size Calculator
Scale standard USDA/AHA food portions to any number of servings in grams and ounces.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this portion size calculator
- Pick a food item from the grouped dropdown (Grains, Pasta & rice, Protein, Vegetables, Fruit, Dairy, or Snacks).
- Enter the number of adult servings you need.
- Press Calculate to see the total weight in grams and ounces plus a one-serving reference.
- Use Copy to paste the result into your shopping list or Reset to start a new calculation.
About this portion size calculator
Portion sizes drift over decades — restaurant pasta plates are 2-3× a standard USDA portion — which makes scaling a recipe or grocery list surprisingly easy to get wrong. The portion size calculator uses the USDA MyPlate and American Heart Association serving definitions as the source of truth, so a "serving" of dry pasta is 75 g (yielding ~1 cup cooked), a serving of chicken breast is 170 g raw (~4.5 oz cooked), and a serving of leafy greens is 50 g. You pick a food and a serving count and the tool scales the per-serving weight.
Worked example: cooking dinner for four with dry pasta as the base. One USDA serving is 75 g. 75 × 4 = 300 g of dry pasta, which is roughly 10.6 oz. That yields about 4 cups cooked pasta — enough for four hearty plates. Switch to chicken breast for the same four people and the tool reports 170 g × 4 = 680 g raw (24 oz), which is the right amount to buy for four ~6 oz cooked portions. These are nutritional reference portions, not hunger targets — use them as a starting point, not a strict diet rule.
FAQ
- Whose definition of a "serving" does the calculator use?
- USDA MyPlate (2020-2025 Dietary Guidelines for Americans) for grains, proteins, fruit, vegetables, and dairy; American Heart Association serving sizes for snacks. Each entry shows its per-serving gram value alongside the result.
- Are the weights raw or cooked?
- For grains and proteins, weights are raw/dry unless the label explicitly says cooked — so 75 g of dry pasta yields about 1 cup of cooked pasta per serving. The note column on each item clarifies which.
- Why grams instead of cups?
- Grams are unambiguous; cups vary with chop, pack, and brand. The tool also reports ounces for shoppers who prefer imperial weights.
- Can I scale a recipe for kids?
- These are adult portions. A typical child serving is about half to two-thirds of an adult portion, depending on age — multiply your kid count by 0.5–0.7 first.
- Is this a diet calculator?
- No. It tells you how much food to buy or cook for a given number of standard portions. It does not compute calories or macros — pair it with a calorie tracker if you need those.
- Are the gram values cited?
- Yes — every portion is sourced from USDA MyPlate or AHA published serving guidelines. The bundled data lives in lib/data/portionSizes.ts in the repo.