Calcro
Food & Baking

Sourdough Hydration Calculator

Calculate the exact flour, water, starter, and salt amounts for any sourdough recipe — with real baker's math that accounts for the flour and water inside your starter.

Quick Presets

Inputs

g
%
Medium-High — Slightly sticky — nice open crumb
%
%
%
Most starters are 100% (equal parts flour and water)

Your Recipe

Flour
471g
Water
314g
Starter
105g
Salt
10.5g
Total: ~900gHydration: 70%

Understanding Sourdough Hydration

Hydration is the backbone of sourdough baking. It refers to the ratio of water to flour in your dough, expressed as a baker's percentage. A dough at 70% hydration means you're using 70 grams of water for every 100 grams of flour. This single number influences nearly everything about your bread — from how the dough feels in your hands to the final texture of the crumb.

Most published recipes sit between 65% and 78% hydration. Lower hydration doughs (below 65%) produce dense, chewy bread with a tight crumb — think bagels or pretzels. Higher hydration doughs (above 75%) create the dramatic open crumb structure you see in artisan loaves and ciabatta, but they demand more skill to handle.

How Baker's Percentages Work

Professional bakers don't think in cups or tablespoons. They use baker's percentages — a system where every ingredient is expressed as a percentage of total flour weight. Flour is always 100%. If your recipe calls for 500g of flour and 350g of water, the hydration is 70% (350 ÷ 500 × 100).

This system makes scaling recipes effortless. Want to make two loaves instead of one? Double the flour, and every other ingredient scales proportionally. Our calculator handles this math automatically — just enter your target dough weight and the percentages you want.

Why Starter Hydration Matters

Here's where many online calculators fall short: they treat starter as a single ingredient, but your sourdough starter is itself a mixture of flour and water. A standard 100% hydration starter is exactly half flour and half water by weight. A stiff starter at 50% hydration is two-thirds flour and one-third water.

This matters because the flour and water in your starter count toward your dough's final hydration. If you ignore this, your actual dough hydration could be off by several percentage points — enough to change how your bread turns out. Our calculator properly separates the flour and water contributions from your starter so the math is precise.

Getting Started

If you're baking your first loaf, use the "Basic Sourdough" preset above. It sets you up at 70% hydration with 20% starter and 2% salt — a proven formula that's forgiving for beginners while still producing excellent bread. As you gain confidence, experiment by bumping the hydration up or down by 2–3% at a time to find the texture you love.

Frequently Asked Questions

Sourdough hydration is the ratio of water to flour in your dough, expressed as a percentage. A 70% hydration dough contains 70g of water for every 100g of flour. This ratio is the single most important factor in determining your bread's texture, crumb structure, and how easy the dough is to handle. Higher hydration produces more open, airy crumb but requires more skill to shape.

If you're new to sourdough, start with 65–70% hydration. At this range the dough is manageable — firm enough to shape without sticking to everything, but wet enough to develop a nice crumb. Once you're comfortable with shaping and feel confident with your bulk fermentation timing, gradually increase hydration by 2–3% at a time.

Divide the total weight of water in your recipe by the total weight of flour, then multiply by 100. The key detail most calculators miss: your starter contains both flour and water. A 100% hydration starter is 50% flour and 50% water by weight. Our calculator accounts for the flour and water inside your starter so your final hydration percentage is truly accurate.

Yes — and this is where many bakers miscalculate. Your starter contributes both flour and water to the final dough. A 100% hydration starter adds equal parts of each, but a stiff starter (50% hydration) adds mostly flour with very little water. Our calculator factors this in automatically so you get the true final hydration of your dough.

The difference is dramatic. At 65% hydration, your dough is firm, easy to shape, and produces a tighter crumb — great for sandwich loaves. At 80%, the dough is wet, sticky, and challenging to handle, but produces an open, irregular crumb with large holes — think ciabatta or high-hydration artisan boules. The sweet spot for most home bakers is 68–73%.

Most recipes call for 15–25% starter relative to total flour weight. Using less starter (10–15%) means a longer, slower fermentation that develops more complex flavor. Using more starter (25–30%) speeds things up but can make your bread taste more sour. The standard 20% is a reliable middle ground for a same-day bake.

Absolutely — that's exactly what this calculator is built for. Enter your desired total dough weight, set your target hydration percentage, and the calculator will give you the exact gram amounts for each ingredient. You can experiment freely: try your favourite recipe at 68% and 75% to see the difference in texture and crumb.