Sourdough Hydration Math: What 65%, 75%, and 85% Actually Do to Your Loaf

Two loaves can list identical flour and water and still behave like different recipes — because the number that governs everything is the ratio, not the amounts. Sourdough hydration is simply water divided by flour, expressed as a percentage. Get the ratio right and the dough tells you what it wants; guess it and you fight the bench all afternoon.

Start with the flour weight as your 100% baseline. For 500 g of bread flour, 65% hydration means 325 g of water, 75% means 375 g, and 85% means 425 g. If you are scaling a recipe up or down and want the amounts to line up cleanly, the cooking converter handles the gram-to-cup conversions for the add-ins.

How the ratio changes the bread

Hydration	Dough feel	Crumb	Best for
60–65%	Firm, barely tacky	Tight, even	Beginners, sandwich loaves, bagels
70–75%	Soft, slight stick	Open but manageable	Everyday boules, batards
80–85%	Wet, spreads on bench	Wide, glossy holes	Ciabatta-style, experienced bakers
90%+	Batter-like	Very open, fragile	Specialty high-extraction flours only

The jump from 75% to 85% is not a 10% difference in difficulty — it is the point where slap-and-fold stops working and you switch to coil folds. That threshold sits around 78% for most bread flours.

A worked batch

Target: two 900 g boules at 75% hydration with 20% levain.

• Bread flour: 1,000 g
• Water: 750 g
• Levain (100% hydration): 200 g
• Salt: 20 g (2%)
• Total dough: ~1,970 g → two 985 g pieces before shaping loss

Note that the levain contributes 100 g of its own water and 100 g of flour. Bakers who ignore that end up at an effective 77–78%, which is exactly why their “75%” dough feels wetter than the recipe promised. Always count levain water into the total. If you are tracking the nutrition side of a bake, the calorie calculator can break down a slice once you know the final baked weight.

Autolyse and why hydration changes it

At 65% hydration, a 30-minute autolyse is enough to hydrate the flour and start gluten development before the levain goes in. Above 80%, extend the rest to 45–60 minutes — the extra water needs time to fully absorb into the bran and endosperm. Skipping this step at high hydration produces a dough that feels wetter than it is, because unabsorbed water sits as a film on the surface.

How temperature shifts effective hydration

Flour absorbs less water when cold. A dough mixed at 18°C (64°F) behaves roughly like a dough one point lower in hydration than the same formula mixed at 25°C (77°F). In winter, add 2–3% water to compensate; in a warm kitchen, subtract the same. This single adjustment explains most “why did my loaf change?” complaints when the seasons turn.

FAQ

Does whole wheat need more water? Yes — add 5–10% hydration for every 25% whole grain in the flour blend.

Why is my 80% dough soupy? Usually an unaccounted-for levain or a flour with lower protein (under 11.5%).

Can I fix an over-hydrated dough? Add flour in 25 g increments and rest 20 minutes between additions — the bran hydrates slowly.

Hydration is the dial that controls your entire process: how you fold, how you shape, how the crumb opens. Pick the number deliberately, count the levain, and the same flour suddenly becomes predictable.