About CrustMath

CrustMath is a small, independent set of free tools for home bakers who want to work in grams: dough calculators built on baker’s percentages, and conversions between grams and cups. There are no accounts, and the calculators run entirely in your browser.

Where the ingredient weights come from

Unless a page says otherwise, grams-per-cup figures come from the USDA FoodData Central database (SR Legacy release, April 2018), which lists measured portion weights for common foods. Each ingredient page links to the exact USDA entry it uses. When USDA measures an ingredient a particular way — cake flour “dipped”, brown sugar “packed”, powdered sugar “unsifted” — we say so on the page.

A few figures are not from USDA and are labelled as such: the weight of a scooped cup of flour (140–150 g, a common kitchen observation), comparisons with King Arthur Baking’s published chart, and yeast conversions and spoon weights (a US packet is ¼ oz / 7 g ≈ 2¼ tsp per Red Star, so about 3.1 g per teaspoon; the yeast converter lists every source), and pizza thickness factors, which are typical values compiled from commonly published dough weights for each style.

A “cup” means a level US cup of about 237 ml (236.6 ml). Metric cups used in Australia, New Zealand and Canada are 250 ml (the UK has no official cup measure; British recipes that give cups usually mean 250 ml), so where we give metric-cup amounts we scale by 250 / 236.6.

Cup measurements are inherently approximate. How you fill the cup can change the weight of flour by 15–20%, which is why we recommend a kitchen scale for anything where precision matters.

Data citation: U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, 2019. fdc.nal.usda.gov. CrustMath is not affiliated with or endorsed by the USDA or King Arthur Baking.

How the dough calculators work

The pizza and sourdough calculators use baker’s percentages: flour is 100%, and every other ingredient is a percentage of the flour weight. The sourdough calculator also accounts for the flour and water contained in the starter, so the hydration you enter is the hydration of the final dough. Yeast quantities are starting points that depend on temperature and time — adjust to your kitchen.

Corrections and contact

If a number looks wrong, email southbench.labs+crustmath@gmail.com and we’ll check it against the source and fix it.

Data last reviewed: October 2026.