Project notes
Sources & methodology
How USDA records become portion comparisons, including preparation states, units and limitations.
What the numbers come from
Every catalogue item is matched to one explicit USDA FoodData Central record in SR Legacy, the historical Standard Reference dataset whose final release was April 2018. The catalogue is a selected set of everyday plant foods, not a complete list of edible plants or a live feed of the newest data.
The underlying source includes values from analysis, calculation and published literature. We have not independently tested these foods. The source age remains visible even when the site’s code or presentation changes.
How portions are calculated
Amount in portion = source amount per 100 g × edible portion in grams ÷ 100. This is a linear scaling calculation. Energy is displayed to the nearest whole kcal, and other nutrients to up to two decimal places. Calculations use unrounded imported amounts. The CSV retains up to four decimal places to make the arithmetic inspectable.
Custom weights range from 1 to 2,000 g. These limits help catch input errors; they are not recommended portion limits. The source numbers are estimates, so extra displayed decimals do not imply that your food has been measured that precisely.
Units and missing values
Protein and fibre are grams (g). Vitamin C, iron, magnesium, potassium, calcium and zinc are milligrams (mg). Vitamin A is micrograms of retinol activity equivalents (µg RAE); vitamin K and total folate are micrograms (µg). Total folate is not the same field as dietary folate equivalents (DFE).
Missing source amounts appear as “Not reported” and are excluded from numeric sorting. Reported zeroes remain zeroes. We do not fill gaps with guessed values or use one variety as an unlabelled replacement for another.
Preparation matters
Read the preparation beside each food and the full USDA description in its expanded row. Fruit and most vegetables here are raw. Pulses are cooked without added salt; nuts and seeds use the specific form in their source record. Edamame is prepared from frozen, tofu is firm and calcium sulfate-set, and the potato entries are cooked.
Weigh the edible portion that matches the record. Do not compare a dry ingredient weight with a cooked record or assume a generic record describes a fortified or salted branded product. Variety, growing conditions, storage and preparation can all affect the food you actually eat.
The league-table score
The league table restores a dedicated ranking using a transparent custom index. It averages capped contributions from ten nutrients per 100 g and scales the highest eligible food in this catalogue to 100. The formula, reference numbers and missing-value rules are shown on that page. Foods missing any required measurement are listed without a score. The index is not clinically validated or a universal rating of healthfulness.
The original site included an antioxidant index that is not used in this version. The comparison tool continues to show separate nutrient amounts so you can inspect the trade-offs and adjust portions.
The tool does not model absorption, individual needs, allergies, food safety, affordability or a whole diet. More of a nutrient or more energy is not automatically better for a person. The comparison tool does not display daily-value percentages. The league uses published reference values only as fixed scales for its custom formula, not as personalised requirements.
Data and editorial maintenance
The data import on 20 October 2026 uses exact FDC IDs and a checked-in selection file. A reproducible importer records the source ZIP’s SHA-256 fingerprint. Future additions should include a matching description, preparation, units and source link before publication. Corrections and substantive changes belong in the public update log; a new date should not be added merely to make a page appear fresh.
Report a data or calculation issue. Include the food, preparation, nutrient and the source you used so the mismatch can be reproduced.