How to use the sourdough calculator
- Enter how many loaves you are baking and how much dough each should weigh.
- Pick a hydration. If you are new to sourdough, start at 68 to 72%.
- Set your starter percentage. 20% suits most recipes.
- Leave salt at 2% unless your recipe says otherwise.
- Weigh out the grams shown, and mix.
With the defaults, one 900 g loaf at 75% hydration needs 458 g flour, 331 g water, 102 g starter and 10 g salt. Change any input and the whole formula updates.
Choosing a hydration
Hydration is the weight of water compared with the weight of flour. It has more effect on how dough feels in your hands than anything else.
| Hydration | How it handles | Good for |
|---|---|---|
| 65 to 70% | Firm, easy to shape, holds its shape well | First loaves, sandwich bread, bagels |
| 70 to 75% | Soft and slightly sticky, still manageable | Everyday country loaves |
| 75 to 80% | Sticky and slack, needs good strength | A more open, airy crumb |
| 80% and up | Very wet, needs practice and strong flour | Ciabatta, focaccia, wide-open crumb |
Whole wheat and rye drink more water than white flour, so a dough with a lot of them can take a higher hydration and still feel the same. The hydration calculator checks the hydration of a recipe you already have.
How much starter to use
The starter percentage is the weight of starter compared with the total flour. It mostly controls speed. At 20%, a dough at about 75°F usually finishes bulk fermentation in an afternoon. Drop to 10% and bulk takes noticeably longer, which can be handy on a warm day or when you want the dough to wait for you. The bulk fermentation chart shows how much time changes.
Why the starter counts
A 100% hydration starter is half flour and half water. In a loaf with 100 g of starter, that is 50 g of flour and 50 g of water that a simple calculation would miss. Leaving it out makes the dough wetter than the number suggests: the default loaf above is 75% hydration overall, but only 72% if you count the added flour and water alone. This calculator includes it, so the hydration you choose is the hydration you get.
Keep a stiff or very runny starter? Change the starter hydration and the flour and water adjust to match.
How big should a loaf be?
A typical home loaf baked in a medium round or oval banneton weighs about 800 to 1,000 g as dough. Smaller bannetons and loaf tins usually suit 500 to 750 g. If your loaves spread or overflow, change the dough weight and the calculator scales everything else.
Salt
Most bread uses salt at about 2% of the flour, which is about 10 g in a single loaf. Salt seasons the bread, tightens the dough and slows fermentation slightly. Add it with a little held-back water so it dissolves evenly.
