Sourdough Hydration Calculator

At 70% hydration with 500g

flour

, you need 350g total water—but 50g is already in your
starter
. This calculator does the math so you get exact amounts every time.

Uses baker's percentages. Accounts for your starter's flour and water contribution automatically.

Calculator

Total Flour (g)

Hydration (%)

Salt (%)

Starter (% of flour)

Starter Hydration (%)

Dough Weight

860g

Effective Hydration

70.0%

Total Water

350g

Salt

10.0g

What to Measure Out

Ingredient	Amount	Notes
Flour (to bowl)	450g	Excludes flour in starter
Water (to bowl)	300g	Excludes water in starter
Starter	100g	Contains 50g flour + 50g water
Salt	10.0g	2% of total flour

Understanding Baker's Percentages

Hydration % = (Total Water ÷ Total Flour) × 100

Baker's percentage is the universal language of bread baking. Every ingredient is expressed as a percentage of the total flour weight. Flour is always 100%. So "70% hydration" means 70g of water for every 100g of flour. This system lets you scale any recipe instantly—just change the flour weight and all other amounts adjust proportionally.

Baked Goods

The key insight with sourdough is that your starter contains both flour and water. A 100% hydration starter (the most common) is equal parts flour and water by weight. So 100g of starter adds 50g flour and 50g water to your dough. If you don't account for this, your actual hydration will be different from your target.

Hydration Guide by Bread Style

Style	Hydration	Flour	Water	Result
Ciabatta	75%	500g	375g	Open, airy crumb
Sourdough Boule	70%	500g	350g	Medium holes, chewy
Bagels	55%	500g	275g	Dense, chewy
Focaccia	80%	500g	400g	Very open, moist
Sandwich Loaf	65%	500g	325g	Soft, tight crumb

Worked Example

Making a sourdough boule at 72% hydration with 500g flour and 20% starter (100% hydration):

Total flour: 500g (including starter flour)
Total water needed: 500 × 0.72 = 360g
Starter: 500 × 0.20 = 100g (contains 50g flour + 50g water)
Flour to bowl: 500 − 50 = 450g
Water to bowl: 360 − 50 = 310g
Salt: 500 × 0.02 = 10g

Total dough weight: 450 + 310 + 100 + 10 = 870g. This makes one large boule or two smaller loaves. The starter contributes significant flour and water—without accounting for it, your dough would be over-hydrated.

Food & Drink

Tips for Dialing In Your Hydration

Start lower, work up. Begin at 65% hydration until you're comfortable with shaping, then increase by 2-3% per bake.
Autolyse improves handling. Mix flour and water first (no salt or starter), rest 30-60 minutes. The dough becomes smoother and more extensible.
Humidity affects results. In humid climates, your flour may already contain more moisture. You might need slightly less water than calculated.
Weigh everything. Volume measurements (cups) are wildly inaccurate for baking. A kitchen scale is essential for consistent results.
Track your bakes. Keep a baking journal noting hydration, timing, temperature, and results. This is how you improve.

Frequently Asked Questions

What is baker's percentage / hydration?

Baker's percentage expresses each ingredient as a percentage of the total flour weight. Hydration is specifically the water-to-flour ratio. At 70% hydration, you use 70g of water for every 100g of flour. This system makes it easy to scale recipes to any batch size.

Cooking & Recipes

What hydration should I use for sourdough?

Most sourdough recipes range from 65-80% hydration. Beginners should start at 65-70%—the dough is easier to handle. As you gain experience, move to 72-78% for more open crumb. Above 80% produces very wet, slack doughs that require advanced shaping skills.

Does my starter count toward hydration?

Yes! A typical sourdough starter is 100% hydration (equal parts flour and water by weight). So a 100g starter adds 50g flour and 50g water to your dough. Our calculator accounts for the starter's contribution to total flour and water.

Why is higher hydration harder to work with?

Higher hydration dough is stickier and more extensible, making it difficult to shape. It requires different techniques—stretch and fold instead of kneading, gentle shaping, and sometimes a banneton for support during proofing. The payoff is a more open, airy crumb with larger holes.

How does flour type affect hydration?

Different

flours

absorb water differently. Whole wheat absorbs 5-10% more water than white

flour

Bread

flour (higher protein) absorbs slightly more than all-purpose. Rye absorbs significantly more. You may need to adjust hydration based on your flour choice.