About Fibermaxxing Calculator

Who makes it

Fibermaxxing Calculator is built and maintained by Alex Lim, an independent developer who builds small, useful web tools. Alex is not a doctor or dietitian, so every number on this site comes from published government data and peer-reviewed research, with sources listed below and on each page.

Found a wrong number, or want a food added? Email [email protected].

Why this exists

Fiber is the nutrient most people fall shortest on, yet counting it is awkward: nutrition apps bury it under calories and macros. This site does one thing well. It tells you how much fiber you ate today and how to get to your target.

How we calculate fiber

• Each food’s fiber per 100 g is the USDA “Fiber, total dietary” value from the National Nutrient Database for Standard Reference (SR28, now published as SR Legacy in FoodData Central).
• Fiber per serving is fiber per 100 g × serving weight ÷ 100, rounded to 0.1 g. Serving weights use USDA household measures (cups, tablespoons, medium fruit) where available.
• Cooked values are used for beans, grains and most vegetables because that is how they are eaten. Dry values are used for oats, flours and cereals.
• Every food page lists the exact USDA food description and NDB number so you can check it yourself.

The database has 256 foods: 32 beans & legumes, 20 seeds & nuts, 61 fruit, 73 vegetables, 49 grains & cereals, 21 snacks & meals.

Real foods vary by variety, ripeness, brand and cooking. Treat numbers as good estimates, and check the label for packaged foods.

Daily targets

US targets are the Adequate Intakes from the National Academies (14 g per 1,000 kcal), used in the Dietary Guidelines for Americans. The UK target is 30 g for adults, from SACN and the NHS. The “Fibermaxxing” setting adds 10 g to your US target, which stays within the range studied in the 2019 Lancet review. See daily fiber needs.

Sources

• U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: SR Legacy (National Nutrient Database for Standard Reference, Release 28).
• National Academies. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005).
• USDA and HHS. Dietary Guidelines for Americans, 2020–2025.
• SACN. Carbohydrates and Health (2015).
• NHS. How to get more fibre into your diet.
• Reynolds A, et al. Carbohydrate quality and human health. The Lancet, 2019.
• Quagliani D, Felt-Gunderson P. Closing America’s Fiber Intake Gap. Am J Lifestyle Med, 2017.

Updates

Last reviewed October 19, 2026. Version 2 added 256 foods, unit switching, shareable results, the 4-week plan, and food-by-food pages.