Why does the starter's hydration matter?

Because the starter is partly flour and partly water. A 100% hydration starter is half flour, half water by weight. A stiff starter at 60% hydration is mostly flour. Ignoring this throws your calculated hydration off by several points.

What's a 'standard' starter hydration?

Most home bakers keep a 1:1:1 (starter:flour:water by weight) starter, which is 100% hydration. Some bakers use stiff starters (60–80% hydration) for a sweeter, more complex flavor.

How accurate is this calculator?

The math is exact — the only source of error is your scale. Weigh in grams, not cups. A typical kitchen scale at ±1g accuracy is more than enough.

What hydration should a beginner aim for?

65–70% is the sweet spot. High enough to develop an open crumb; low enough that the dough is forgiving to handle and shape.

Does this work for non-sourdough bread?

Yes — for any recipe with a preferment (poolish, biga, levain). Just enter the preferment's hydration in place of the starter's.

Free baking tool

Sourdough Hydration Calculator

Most recipes ignore the flour and water locked inside your starter, so the hydration you think you're baking at isn't the hydration you actually are. This calculator fixes that.

Added flour (g)Flour you'll add to the dough — not counting starter.Added water (g)Water you'll add to the dough — not counting starter.Starter (g)Total weight of starter you'll add to the dough.Starter hydration (%)A standard 1:1:1 starter is 100%. A stiff starter is 60–80%.Salt (g)Used to compute baker's percentage for salt.

True hydration

72.7%

Total flour

550 g

Total water

400 g

Total dough

960 g

Salt %

1.82%

Inoculation

20.0%

Reading: Classic country sourdough. Soft and slightly tacky; balanced crumb.

How hydration is actually calculated

Hydration is the ratio of total water to total flour in the dough, expressed as a percentage. The catch is that your starter is part of the dough. If you keep a 100% hydration starter (equal weights of flour and water), then 100g of starter contributes 50g of flour and 50g of water to your final dough.

The formula:

hydration % =
  (added_water + starter_water) /
  (added_flour + starter_flour)
  × 100

Hydration ranges and what they feel like

60–65% — Firm, easy to handle. Tight crumb. Great for beginners and sandwich loaves.
68–72% — Classic country sourdough. Soft, slightly tacky. Open but predictable crumb.
73–78% — Sticky, demands wet hands and confidence. Beautifully open crumb when handled well.
79–85%+ — Slack, almost pourable. Ciabatta territory. Expect a learning curve.

FAQ

Why does the starter's hydration matter?: Because the starter is partly flour and partly water. A 100% hydration starter is half flour, half water by weight. A stiff starter at 60% hydration is mostly flour. Ignoring this throws your calculated hydration off by several points.
What's a 'standard' starter hydration?: Most home bakers keep a 1:1:1 (starter:flour:water by weight) starter, which is 100% hydration. Some bakers use stiff starters (60–80% hydration) for a sweeter, more complex flavor.
How accurate is this calculator?: The math is exact — the only source of error is your scale. Weigh in grams, not cups. A typical kitchen scale at ±1g accuracy is more than enough.
What hydration should a beginner aim for?: 65–70% is the sweet spot. High enough to develop an open crumb; low enough that the dough is forgiving to handle and shape.
Does this work for non-sourdough bread?: Yes — for any recipe with a preferment (poolish, biga, levain). Just enter the preferment's hydration in place of the starter's.

Want timing that adapts to your kitchen too?

SourdoughAI does for fermentation what this calculator does for hydration — it takes the variables most recipes ignore and gives you a number you can actually use.

See SourdoughAI