Sourdough Hydration Calculator — Rex's Toolbox

Rex says

Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.

Try a scenario

Click to load — tweak from there.

Inputs

Total flour(g)

Target hydration(%)

Starter(%)

Salt(%)

Result

Flour to add (g)

900

Water to add (g)

650

Starter (g)

200

Salt (g)

20.0

Total dough weight (g)

1770

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How to use this

1Enter total flour (g).
2Enter target hydration (%).
3Enter starter (%).
4Enter salt (%).
5Read your flour to add (g) on the right — it updates as you type.
6Hit Share to keep the scenario or send it to someone.

About this calculator

Enter total flour, target hydration, starter percentage, and salt percentage to get every weight in grams — including the flour and water hiding inside your starter.

FormulaBaker's % = ingredient ÷ total flour. Starter at 100% hydration is half flour, half water.

Worked example

Using the values the calculator loads with:

Inputs

Total flour: 1000 g
Target hydration: 75 %
Starter: 20 %
Salt: 2 %

Results

Flour to add (g): 900
Water to add (g): 650
Starter (g): 200
Salt (g): 20
Total dough weight (g): 1,770

What each field means

Inputs

Total flour (g): The total flour used in the calculation, measured in g. Starts at 1000 g so you have a working example on load.
Target hydration (%): The target hydration used in the calculation, measured in %. Starts at 75 % so you have a working example on load. Accepted range: 50–100 %.
Starter (%): The starter used in the calculation, measured in %. Starts at 20 % so you have a working example on load. Accepted range: 0–50 %.
Salt (%): The salt used in the calculation, measured in %. Starts at 2 % so you have a working example on load. Accepted range: 0–4 %.

Results

Flour to add (g): Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Water to add (g): Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Starter (g): Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Salt (g): Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Total dough weight (g): Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

Does this assume 100% hydration starter?

Yes — equal flour and water by weight, which is the most common maintenance schedule.

What hydration should a beginner use?

68–72% is far easier to shape than 80%+. Raise it once the dough stops sticking to everything you own.

Accuracy and limitations

Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Results are rounded for readability; add a buffer before ordering, booking, or committing.
Double-check anything with a real cost attached against a local quote.

Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA

RevenueLab. (2026). Sourdough Hydration Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/sourdough-hydration

HTML

<p>Source: <a href="https://www.revenuelab.fyi/toolbox/sourdough-hydration" target="_blank" rel="noopener">Sourdough Hydration Calculator — RevenueLab</a> (2026).</p>

Markdown

Source: [Sourdough Hydration Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/sourdough-hydration) (2026).