Data and Methodology

Last updated: October 2026

Every number on Nutrinfo comes from a public, citable source. This page explains where the data comes from and how each figure on our food pages is calculated, so you can check our work.

Data source

Food composition data comes from USDA FoodData Central, published by the U.S. Department of Agriculture's Agricultural Research Service. We use the SR Legacy dataset (April 2018 release), the final version of the USDA National Nutrient Database for Standard Reference. It covers 7,793 foods with up to 150 nutrients each, measured by laboratory analysis or calculated by USDA from ingredients.

We do not edit USDA values. Every food page links to the original USDA record by its FDC ID so you can compare the numbers directly.

Per 100 g and serving sizes

USDA reports nutrients per 100 g of the edible portion, so that is our default. Serving sizes in the nutrition label (for example "1 cup, sliced" or "1 medium") come from the household measures USDA publishes for each food. When you pick a serving or type a weight, we scale every nutrient in proportion: amount per serving = amount per 100 g x grams / 100.

Percent Daily Value (% DV)

% DV compares a nutrient amount to the reference intake the U.S. Food and Drug Administration uses on nutrition facts labels for adults and children 4 years and older, based on a 2,000 calorie diet. We calculate it as amount / Daily Value x 100 and round to the nearest whole number. Your own needs may be higher or lower depending on age, sex, body size, pregnancy and activity.

Calorie breakdown

The protein, carbs and fat percentages use the standard Atwater factors: 4 kcal per gram of protein, 4 kcal per gram of carbohydrate and 9 kcal per gram of fat. Because USDA calorie values use food-specific factors and alcohol and fiber are counted differently, these percentages are a close guide rather than an exact split of the listed calories.

Calorie targets

The calorie calculator subtracts 250 or 500 kcal from your TDEE for weight loss and adds 300 kcal for lean gain. The embeddable widget can instead use percentages (10%, 15% and 20% below TDEE, and 10% above), which some coaches and dietitians prefer. Weight-loss targets never go below 1,200 kcal a day for women or 1,500 kcal for men.

Net carbs

Where we show net carbs, it is total carbohydrate minus dietary fiber. Sugar alcohols are not subtracted.

Category averages and comparisons

Foods are grouped using USDA's own food categories. A category average is the mean value across all foods in that category that report the nutrient. "Similar foods" and "alternatives" are picked from the same category: alternatives show foods with at least 20% more protein and no more than 10% extra calories, or at least 20% fewer calories, closest in calories to the food you are viewing.

"Foods high in" rankings

Rankings sort foods by the amount of a nutrient per 100 g. The "everyday foods" list leaves out spices and herbs, baby foods, beverages and dried, powdered or freeze-dried products, which can look extreme per 100 g but are rarely eaten in that amount.

AI features

The AI Meal Analyzer and Ask AI use a large language model to estimate the nutrition of a described or photographed meal and to answer general questions. These are estimates, not measurements, and they can be wrong. For precise values use the USDA numbers on our food pages.

Limitations

Corrections

If you spot an error, email [email protected] with the page link and what looks wrong. We check every report against the USDA source and fix confirmed errors.