Sourdough Hydration Explained (Without the Maths Anxiety)

Hydration is the number everyone quotes and few people explain. It sounds technical. It isn't — it's one division, and once you understand it you stop following recipes blindly and start adjusting them.

The one calculation

Hydration = water ÷ flour × 100.

500g flour, 350g water: 350 ÷ 500 = 0.70, so 70% hydration. That's it.

The percentage is relative to flour, not to the total, which is why hydration figures can exceed 100% in some batters without anything being wrong.

One thing that trips people up: your starter contains both flour and water. A starter fed 1:1:1 is half flour, half water, so 100g of starter adds 50g to each side of the sum. Most recipes have already accounted for this. If you're building your own, remember to.

What the number actually predicts

Hydration tells you two things: how the dough will feel in your hands, and what the crumb will look like.

60–65% — stiff. Handles like modelling clay. Holds shape effortlessly, easy to shape, tight even crumb. This is sandwich bread and bagel territory. Deeply unfashionable and genuinely useful.

65–70% — the sensible starting point. Slightly tacky but manageable. Holds shape well. Open enough crumb to look like proper sourdough. If you're new, start here and stay here for a month.

70–78% — the classic country loaf. Sticky, needs wet hands and a bench scraper, needs real shaping technique. Open irregular crumb, thin crisp crust. This is what most photographs are.

78–85% — difficult. Slack, spreads if you look away, needs a well-developed gluten structure and confident handling. Very open crumb, dramatic holes.

85%+ — ciabatta and focaccia. Barely a dough. Poured rather than shaped.

Higher is not better

The internet has a bias toward high hydration because open crumb photographs well. But an 80% loaf that spread into a pancake is worse bread than a 68% loaf that came out tall, and holes are not flavour.

Higher hydration also makes every other mistake worse. Underfermented dough at 65% is a bit dense; at 80% it's a puddle. Starting low isn't a compromise — it's how you learn to read dough without three variables shouting at once.

If your loaves are coming out dense, hydration is rarely the cause — see why is my sourdough dense for the more likely culprits.

Your flour changes the answer

The same percentage feels completely different depending on what you're using.

Wholemeal absorbs far more water — the bran soaks it up. A 75% wholemeal dough handles roughly like a 68% white dough. If you swap in wholemeal without raising the water, you'll get a stiff, tight loaf.

Rye absorbs even more and behaves differently again — sticky without being stretchy, because rye has little gluten.

Strong bread flour takes more water than plain flour. More protein, more absorption. A recipe written for strong flour will run wet if you use plain.

So a recipe's hydration number is only meaningful alongside its flour. This is why the same 75% recipe works for one person and floods for another.

How to actually raise your hydration

Not in one jump. Go up 2–3% at a time and bake at least twice at each level.

What makes wetter dough manageable is technique, not tolerance:

• Wet your hands instead of flouring the dough. Flour changes the recipe; water doesn't stick.
• Use a bench scraper for everything. It's the single tool that makes wet dough possible.
• Autolyse — mix flour and water, rest 30–60 minutes before adding starter and salt. The flour hydrates fully and the dough becomes noticeably easier to handle.
• More stretch-and-folds, spaced 30 minutes apart during the bulk, to build structure that holds the water.

Write the number down

Hydration is the easiest variable to track and the one most worth tracking, because its effects are visible in the finished loaf. Note the percentage, the flour, and the kitchen temperature — three numbers, and after six bakes you'll have your own reference table, which beats anyone else's recipe. That's what a baking notebook earns its place for.

Questions we get asked

What hydration should a beginner start at?

65–68% with strong white flour. It's manageable by hand, holds its shape, and still gives a properly open crumb. Stay there until shaping feels automatic.

Does higher hydration mean better bread?

No. It means a more open crumb and a thinner crust, and it amplifies every other error. A well-fermented 68% loaf beats a badly handled 80% one every time.

Do I count my starter in the hydration?

Yes — a 1:1:1 starter is half flour and half water, so 100g of it adds 50g to each side. Most published recipes have already done this for you.

Why does the same recipe feel wetter for me?

Flour. Wholemeal and rye absorb much more water than white, and strong bread flour absorbs more than plain. A hydration percentage only means something alongside the flour it was written for.