Where our numbers come from
Every value on YummyMetrics traces back to public USDA data. Here's exactly which data we use, what we do to it, and where its limits are.
1. Data source
Our nutrient data comes from FoodData Central, the integrated food composition database of the U.S. Department of Agriculture's Agricultural Research Service. FoodData Central data is in the public domain. We use two of its datasets:
| Dataset | Release used | What it is |
|---|---|---|
| Foundation Foods | April 2026 | Current, regularly updated analytical data for minimally processed foods, with detailed information about samples and methods. |
| SR Legacy | April 2018 (final) | The former USDA National Nutrient Database for Standard Reference — broad coverage of thousands of foods. No longer updated, but still the most complete reference set. |
We don't use FoodData Central's Branded Foods data (manufacturer-submitted labels for packaged products). We may add common prepared dishes from the FNDDS dataset in future.
2. How we curate the data
FoodData Central contains many very similar entries. To make ingredients easy to find and compare, we:
- Prefer Foundation Foods. When the same food exists in both datasets, we use the newer Foundation Foods values and fill in nutrients it doesn't report from SR Legacy only where the foods clearly match.
- Merge near-duplicates. Entries that differ only in minor ways are combined under one clear ingredient, while keeping the forms people actually cook with — for example raw and boiled, or with and without skin.
- Use plain names. USDA descriptions like “Chickpeas (garbanzo beans, bengal gram), mature seeds, cooked, boiled, without salt” become “Chickpeas, boiled”. The original description and FoodData Central ID are kept on each ingredient page.
- Group by food type. Each food is assigned to one group: vegetables, fruits, grains, legumes, nuts and seeds, dairy, eggs, meat, poultry, fish and seafood, fats and oils, herbs and spices, sweeteners, pantry staples and condiments (baking ingredients, sauces, dressings, stocks and cooking liquids), and everyday foods — baked goods, snacks, desserts, beverages and soups.
- Add search synonyms. So “garbanzo”, “courgette” and “zucchini” all find the right food.
- Translate names and household measures. On the Spanish and French versions every food has its local name, and USDA measures such as “1 cup, chopped” are translated (“1 taza, picado”, “1 tasse, haché”), always with the weight in grams.
We never alter USDA nutrient values to “improve” them. Changes are limited to selection, naming, grouping, translation and unit conversion.
3. Nutrients we show
| Nutrient | Unit | Notes |
|---|---|---|
| Energy | kcal | As reported by USDA. Where only Atwater-factor energy values are given (common in Foundation Foods), we use the specific Atwater value, or the general one if that's all that's available. |
| Protein | g | |
| Carbohydrate | g | Total carbohydrate “by difference”, which includes fiber. For the few Foundation Foods that report only carbohydrate “by summation”, we use that value. |
| Fat | g | Total lipid (fat). |
| Fiber | g | Total dietary fiber. |
| Sugars | g | Total sugars. |
| Sodium | mg | |
| Vitamins and minerals | mg / µg | Shown on ingredient pages where USDA reports them. |
A blank or “—” means USDA doesn't report a value for that food. It does not mean zero.
4. Per 100 g, per portion and per 100 kcal
- Per 100 g is the USDA's own basis and our default. All values refer to the edible portion — no peel, pits, bones or shells.
- Per portion defaults to 100 g for every food. You can switch to a household measure from FoodData Central (such as “1 cup, chopped” or “1 medium”) where USDA provides one; the weight in grams is always shown alongside.
- Per 100 kcal scales every nutrient to the amount of food that provides 100 kcal. It's useful for comparing nutrient density — for example, how much protein you get for a given number of calories.
Macro bars show the share of energy from protein, carbohydrate and fat, using 4 kcal/g for protein and carbohydrate and 9 kcal/g for fat. Because USDA energy values use more precise factors, these shares are approximate.
5. Rounding and display
We store full-precision USDA values and round only for display: energy to whole kcal, macronutrients to one decimal place in grams, and minerals and vitamins to sensible precision for their size. Totals in our tools are calculated before rounding, so a total may differ slightly from the sum of rounded parts.
6. How our tools calculate
Our recipe calculator reads each line of your recipe, recognises a quantity, a unit and an ingredient, converts the amount to grams using USDA portion weights or standard unit conversions, and adds up the nutrients. It then divides by the number of servings. Each matched ingredient is shown so you can check and correct it. Results are estimates and do not account for nutrients lost or gained in cooking unless you choose a cooked form of the ingredient.
7. Limitations
- Values are averages for representative samples. Individual foods vary.
- SR Legacy has not been updated since 2018, so some values reflect older analyses or older food formulations.
- Data reflects foods as sampled in the United States. Varieties, fortification and processing differ by country.
- Not every nutrient is reported for every food.
For medical or dietary decisions, please read our Health Disclaimer and consult a qualified professional.
8. Attribution and citation
Nutrition data: USDA FoodData Central. The USDA does not endorse YummyMetrics or any product or service mentioned on it.
U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, 2026. fdc.nal.usda.gov.
If you cite YummyMetrics, please also cite the original USDA source above.
9. Report an error
If a value looks wrong, a food is in the wrong group, or something important is missing, please tell us with the ingredient name and page link. We check every report against the source data and fix confirmed errors promptly.