About
Sourdough math, made calm
A small, free calculator for home bakers who want exact weights without a spreadsheet.
Most sourdough calculators forget one thing: your starter is made of flour and water too. Add 200 g of starter to a recipe and you’ve quietly added about 100 g of flour and 100 ml of water, which changes your real hydration.
SourdoughRatio counts that for you. Tell it how much dough you want, your hydration, starter and salt percentages, and it returns exactly what to weigh out, in grams, kilograms, ounces or pounds.
Starter-aware
Flour and water inside the starter are subtracted from what you add, so hydration is true to the bowl.
Private by design
Everything runs in your browser. No accounts, no uploads.
Simple first
Start in Simple mode with four inputs. Switch to Advanced for flour blends, scaling and a levain builder.
Want to see the math?
The exact formulas, a worked example and typical percentages are all on the home page. Spotted something wrong, or have an idea? We’d love to hear it.
More tools
More sourdough calculators
Sourdough Calculator
Flour, water, starter and salt for any dough weight.
Sourdough Hydration Calculator
Find the hydration of a dough you have already mixed.
Baker’s Percentage Calculator
Turn any ingredient list into baker’s percentages.
Starter Ratio Calculator
The feeding ratio and amounts for your starter.