Food nutrition analysis: calories, macros and serving weights

Analyze calories, protein, carbohydrate, fat and fiber from food weights. Learn per-100-g scaling, raw versus cooked differences and how to interpret missing nutrients.

How food nutrition is calculated

For each reported nutrient: amount in your portion = value per 100 g × edible grams ÷ 100. A meal total adds the calculated amounts for its ingredients. Shells, bones and other inedible parts should not be counted as edible weight.

What a nutrition analysis can and cannot tell you

This example reports calories and macronutrients from USDA SR28. Detailed food pages can also show source-reported vitamins, minerals and official portions when those records provide them. A nutrient table does not diagnose deficiency, determine absorption or replace a product label.

Missing is different from zero

A recorded zero can be added as zero. An unreported nutrient remains unknown; summing other ingredients cannot make the meal total complete. Keep g, mg and µg separate, and do not add incompatible vitamin expressions such as IU and RAE.

Cups and portions need food-specific weights

A cup of milk, cooked rice and oil do not have the same mass. Use the selected food’s reported gram weight or weigh your portion. Do not use water density as a universal conversion. Select the exact raw/cooked food and check the source description.

Sample meal nutrition: adjust ingredient weights

This illustrates meal arithmetic, not a weight-loss prescription or a complete daily diet. Defaults: 120 g roasted chicken breast, 150 g cooked rice, 150 g cooked broccoli and 5 g additional olive oil.

Food / source	Calories	Protein	Carbohydrate	Fat	Dietary fiber
Chicken, broilers or fryers, breast, meat only, cooked, roasted USDA SR28 (2015) · NDB 05064	198 kcal	37.22 g	0 g	4.28 g	0 g
Rice, white, long-grain, regular, enriched, cooked USDA SR28 (2015) · NDB 20045	195 kcal	4.04 g	42.26 g	0.42 g	0.6 g
Broccoli, cooked, boiled, drained, without salt USDA SR28 (2015) · NDB 11091	52.5 kcal	3.57 g	10.77 g	0.61 g	4.95 g
Oil, olive, salad or cooking USDA SR28 (2015) · NDB 04053	44.2 kcal	0 g	0 g	5 g	0 g

Adjusting grams updates individual nutrients and the total below. — means unknown.

Calories: 489.7 kcal · Protein: 44.83 g · Carbohydrate: 53.03 g · Fat: 10.32 g · Dietary fiber: 5.55 g

Per-100-g values come from the built-in USDA SR28 (2015) records, not laboratory testing or live branded labels. This table is not a complete micronutrient analysis and excludes additional sauces.

Open these portions in the original meal calculator

With JavaScript enabled, this link follows the portions above; continue editing and export CSV in the combination calculator.

Sources and further reading

USDA FoodData Central / SR Legacy · NHS Eatwell Guide

Boiled egg nutrition and portions · Milk nutrition and portions · All food guides