All crumbmath calculators follow the same conventions, so results from one tool can be carried into another.
Conventions
- Weights in grams. Volume measures are too inconsistent for flour and starter.
- Baker's percentages of total flour. Total flour means the flour you add plus the flour inside any starter or levain. Hydration, salt and starter percentages are all relative to it.
- Starter hydration is the water you feed it divided by the flour you feed it. A starter fed equal weights is 100%.
The core step: splitting a starter
Flour in starter = starter weight ÷ (1 + hydration)
Water in starter = starter weight − flour in starter
A 150 g starter at 50% hydration holds 100 g flour and 50 g water. Every calculator uses this step, which is why they agree with each other.
Formulas by calculator
- Hydration: (water + water in starter) ÷ (flour + flour in starter).
- Recipe builder: total flour = dough weight ÷ (1 + hydration + salt), then the starter's share is subtracted from the flour and water to add.
- Starter feeding: the ratio is split by parts, and the hydration after feeding counts the seed's own flour and water.
- Levain build: solves exactly for fresh flour, water and seed so the finished levain hits both its weight and its hydration, including the seed's water.
- Water temperature: the standard desired dough temperature method, target × number of factors minus the known temperatures and friction.
- Schedule planner: lays your own step durations end to end from a start or finish time. It does not predict fermentation.
How results are checked
Each formula lives in one shared code module. Automated tests run it against the worked examples published on the calculator pages, plus edge cases such as stiff starters and impossible inputs, every time the site is rebuilt. A change that breaks an example cannot be published.
Rounding
Weights of 20 g or more are shown to the nearest gram; smaller weights to a tenth of a gram, since salt and small seed amounts benefit from a precise scale.
Corrections
If a result looks wrong, email hello@crumbmath.com with your inputs. Confirmed errors are fixed and noted on this page.