Baker's Percentage Calculator for Sourdough

How it works

Baker's percentages express every ingredient as a share of the total flour weight. Flour is always 100%. With that, a recipe becomes a short list of ratios that scales to any batch size.

The calculator takes total flour F (or works it out from the dough weight), then:

1. Total water = F × hydration.
2. Salt = F × salt %.
3. Starter = F × starter %.
4. The starter's flour = starter ÷ (1 + starter hydration); its water is the rest.
5. Flour to add = F − starter's flour. Water to add = total water − starter's water.

Working from dough weight, it first finds F = dough weight ÷ (1 + hydration + salt %). The starter does not appear in that sum because its flour and water are already counted in the totals.

Worked example

500 g total flour, 75% hydration, 2% salt, 20% starter at 100% hydration:

The dough weighs 885 g before baking.

Why count the starter?

King Arthur Baking's hydration guide makes the point directly: the flour and water in a sourdough preferment count toward the dough's total hydration, because everything in the loaf you put in the oven is part of the loaf. If you ignore the starter, a dough you think is 75% can really be several points higher or lower, depending on how stiff your starter is.

Choosing your percentages

• Hydration: firmer doughs sit around 60–65%; above about 80% doughs are slack and sticky and need more careful handling. Whole-grain flours absorb more water, so the same hydration feels firmer with whole wheat. See our hydration guide.
• Salt: professional references give 1.8–2% of flour weight. More tastes salty and slows fermentation; less gives flat-tasting bread and slack dough. See salt in bread dough.
• Starter: the percentage varies a lot by recipe and schedule. More starter generally means faster fermentation; less gives a longer, slower rise.

Tips for accurate results

• Weigh everything in grams. A cup of flour can weigh quite different amounts depending on how it's scooped.
• Use a starter that is at or near its peak, and know its hydration (a 1:1:1 feed by weight is 100%).
• Hold back a little of the water when trying a new flour, then add it if the dough feels stiff.
• Write down the percentages, not just the grams. Next time you can scale to any size in seconds.

Related tools

Check an existing recipe's true hydration with the hydration calculator, feed your starter to the right amount with the starter feeding calculator, and set your water temperature with the dough temperature calculator.

Common questions

How much water for 500 g flour at 75% hydration?

375 g of water in total. If 100 g of 100% hydration starter is in the dough, 50 g of that water comes from the starter, so you add 325 g.

Is starter percentage based on total flour or the flour I add?

Conventions differ between recipes. This calculator uses total flour, including the flour inside the starter, for every percentage. Check which convention a recipe uses before converting it.

How do I make two 900 g loaves?

Switch to 'Total dough weight', enter 2 loaves at 900 g, and the calculator works backward: at 75% hydration and 2% salt, that is about 1,017 g total flour.

Why does my dough weigh less after baking?

Water evaporates in the oven, so a baked loaf weighs less than its dough. The dough weight here is before baking.