Sourdough Math Made Simple
Purpose-built calculators for every step of the sourdough process. No signup, no email, no waiting — just open and use.
Calculators
Hydration Calculator
Work out your dough’s true hydration in seconds, including starter contribution.
Open calculator →Starter Feeding Calculator
Exact flour and water amounts for any feeding ratio, with estimated peak time.
Open calculator →Baker’s Percentage Converter
Convert any recipe to baker’s percentages or scale from percentages to weights.
Coming soonTimeline Generator
Plan your bake schedule around your life. Feed, bulk, shape, bake — timed to your clock.
Coming soonRecipe Scaler
Scale any recipe up or down by loaf count or total dough weight.
Coming soonWhy The Granarchist
Most sourdough calculators online are afterthoughts — a single text field bolted onto a recipe blog, rounding to whole numbers, ignoring the flour and water hiding inside your starter. That is not good enough when you are trying to hit a specific hydration or time a bake around your work schedule. We built these tools because we needed them ourselves, and because the math matters more than most bakers realize.
Baker’s percentage is the universal language of bread. It lets you compare any two recipes at a glance, scale a formula to any batch size without recalculating from scratch, and understand exactly what changing one variable — more water, less starter, a longer bulk — will do to your loaf. Once you think in percentages, recipes stop being prescriptions and start being starting points you can adapt to your flour, your climate, and your schedule.
Every calculator here accounts for the details that simpler tools skip. The hydration calculator includes your starter’s flour and water contribution. The feeding calculator estimates peak time based on your kitchen temperature, not just a generic “4–8 hours.” As we add more tools — a timeline generator, a recipe scaler, a baker’s percentage converter — each one will be built with the same philosophy: do the math right, show the answer fast, and stay out of the way.
We assume you care about doing this well. You are not here for a shortcut; you are here because you want to understand what is happening in your dough and make better decisions. These tools are for you.
Frequently Asked Questions
Why use baker's percentage instead of just following a recipe?
Baker's percentage makes every recipe portable. Because each ingredient is expressed as a percentage of the total flour weight, you can scale to any batch size instantly and compare recipes at a glance. A recipe that calls for 70% water tells you exactly how the dough will feel regardless of whether you are making one loaf or ten.
Do I really need a kitchen scale for sourdough?
Yes. Volume measurements (cups, tablespoons) vary by 20–30% depending on how you scoop. That margin of error is larger than the difference between a stiff dough and a slack one. A basic digital scale accurate to 1g costs under $15 and removes the single biggest source of inconsistency in home baking.
Can I convert volume-based recipes to weights?
You can, but it requires knowing the density of each ingredient. A cup of bread flour weighs roughly 120–130g; a cup of whole wheat is closer to 140g. Water is the easy one at ~237g per cup. Our calculators work in weights from the start, which avoids the conversion problem entirely.
Does this site collect my data?
No. All calculations run entirely in your browser. Nothing is sent to a server. Your inputs are saved in the URL hash so you can bookmark or share results, but that data never leaves your device unless you choose to copy the link.
Why is this free?
The site is supported by ads. We would rather give every baker access to accurate tools than charge for basic math. If the ads bother you, we understand — the calculators still work fine with an ad blocker.