Sourdough hydration explained simply — what the percentage means, how to calculate it, and how to use it to predict the texture, crumb, and difficulty of any sourdough recipe before you mix.
Sourdough recipes talk about hydration like it's a special language. 72% hydration. 80%. Going for 85% on this one. Here's what nobody tells you upfront: it's just a way of describing how wet your dough is. Once you understand the maths — which takes about three minutes — you can predict exactly how a recipe is going to behave before you mix a thing.
Hydration is the weight of the water in your dough as a percentage of the weight of the flour. It's calculated using baker's percentages, where flour is always treated as 100%.
The formula:
Hydration % = (water weight ÷ flour weight) × 100
So if a recipe calls for 500g flour and 350g water:
(350 ÷ 500) × 100 = 70% hydration
That recipe is 70% hydration. It tells you nothing about the size of the loaf or whether it'll be tasty — it tells you how slack and wet the dough will be in your hands.
| Hydration | Feels like | Best for |
|---|---|---|
| 60–65% | Stiff, easy to handle, almost like pasta dough | Bagels, pretzels, baguettes |
| 65–70% | Firm but supple, holds shape easily | Sandwich loaves, plain country bread, beginners |
| 70–75% | Soft and slightly tacky, a bit of stretch | Most classic sourdough country loaves |
| 75–80% | Wet and slack, can pour off the counter | Open-crumb sourdough, focaccia, ciabatta |
| 80–90% | Almost batter-like, hard to shape | Experienced bakers chasing huge holes |
| 90%+ | Pours like thick yoghurt | Pan loaves and ciabatta only — not free-form |
Higher hydration means more steam inside the dough during baking, which means a more open crumb (bigger, more irregular holes), a thinner crust, a softer interior, and a longer shelf life. Sounds great — except higher hydration is also harder to handle, takes more practice to shape, and is far less forgiving of timing errors.
For a beginner, anything above 75% is usually a struggle. For an experienced home baker, 78–82% is a sweet spot. For exhibition-grade open-crumb sourdough, 85%+ — and a lot of failed loaves on the way.
This is where it gets fiddly. A 100% hydration starter is half flour, half water. So if your recipe uses 100g of starter, that's 50g flour and 50g water that need to be added to the totals.
Worked example. The recipe says:
True hydration calculation:
The recipe might be marketed as 70% hydration (water-to-flour without the starter), but the actual hydration of the dough is closer to 73%. For most beginners it doesn't matter. For high-hydration experiments it does — every percentage point counts when you're at the edge of what dough can hold.
Say you have a 75% recipe and you want to try it at 70% because you're a beginner. Keep the flour the same and recalculate water:
New water = flour weight × (new hydration ÷ 100)
For 500g flour at 70%:
500 × 0.70 = 350g water
So you drop from 375g (75%) to 350g (70%). Don't change anything else — same starter, same salt.
Three factors push your ideal hydration up or down:
Strong bread flour can hold more water than plain. Wholemeal absorbs much more — wholemeal at 70% feels like white at 65%. If you switch to a higher-protein flour mid-recipe, you'll need to add more water to keep the dough feeling the same.
Humid summer kitchens make dough feel wetter than they really are. Dry winter kitchens (especially with central heating) can dry dough out fast. UK kitchens hover around 50–60% humidity year-round — easy to bake in, no extreme adjustments needed.
This is the big one. A skilled baker can wrestle 85% dough into a high-rise loaf because they've trained their hands to know the texture. A beginner trying the same dough drops it on the way to the banneton.
If you're new to sourdough, climb this ladder one rung at a time. Bake at least three loaves at each level before moving up.
Forget percentages for a second. Hydration is really about the feel of the dough, and you'll get there faster by training your hands than by memorising numbers.
Starter at 100% hydration. Numbers are total water needed for 500g flour, including the water in the starter.
| Target hydration | Water (no starter) | Water (100g starter) | Water (200g starter) |
|---|---|---|---|
| 65% | 325g | 307g | 290g |
| 70% | 350g | 335g | 320g |
| 75% | 375g | 363g | 350g |
| 80% | 400g | 390g | 380g |
| 85% | 425g | 418g | 410g |
People forget that the starter contains flour as well as water. They calculate hydration as water ÷ flour-in-the-recipe, ignore the starter, and end up with wetter dough than they thought. A recipe with 200g of starter actually has 100g of flour and 100g of water hidden inside it — that has to count.
The fix is to use the formula at the start of this guide: total water (including starter water) divided by total flour (including starter flour). Once you build the habit, you'll glance at a recipe and know within a second how it'll handle.
65–70%. Easy to handle, easy to shape, gives a solid loaf with a moderately open crumb. Our classic white country loaf is at 70%.
No. Higher hydration gives a more open crumb and softer interior, but it's harder to handle and easier to ruin. A perfectly executed 70% loaf beats a sloppy 80% one every time.
Higher hydration ferments faster because the yeast has more access to water and nutrients. An 80% dough might bulk in 4 hours where a 65% dough needs 5–6 at the same temperature.
Yes — this is called "bassinage" and it's a real bakery technique. Wet your hand, dribble in water during stretch-and-folds, and pinch it through. Add 15–25g at a time, never more.
Around 85%, with strong bread flour and a skilled hand. Above that you need a tin or a couche to support the loaf in the final proof.
Hydration changes more than the look of the loaf — it changes the schedule. Here's a quick overview of how the same recipe behaves at different water levels.
| Hydration | Bulk time at 24°C | Stretch-and-folds needed | Cold retard tolerance |
|---|---|---|---|
| 65% | 5–6 hours | 3–4 sets | Up to 36 hours |
| 70% | 4.5–5.5 hours | 4 sets | Up to 24 hours |
| 75% | 4–5 hours | 4–5 sets | 16–20 hours |
| 80% | 3.5–4.5 hours | 5–6 sets, gentle | 12–16 hours |
| 85%+ | 3–4 hours | 6+ sets, very gentle | Maximum 12 hours |
Higher hydration ferments faster but tolerates less retard, because the dough's structure is held together by gluten alone — and gluten weakens slowly in the fridge. A 65% loaf can sit in the fridge for 36 hours and still bake well; an 85% loaf left that long collapses.
Flour absorbs water differently. The percentage on the bag is your starting point, not the finished hydration of your dough. Here's how the same 75% recipe behaves with different flours, and how to adjust:
If you blend flours, calculate per ingredient and add up. A 70/30 blend of white/wholemeal at 75% needs roughly 2% more water than pure white at 75%.
Most home bakers don't want to do calculations every time. Here's a shortcut: memorise three numbers for the flour you use most, and you're set.
From those, your water is always: (flour × hydration) - (starter weight ÷ 2). So for 500g flour at 72% with 100g starter: (500 × 0.72) - 50 = 360 - 50 = 310g water. The whole recipe locks into place.
The longer you bake, the less you'll think in percentages and the more you'll think in feel. After fifty loaves, you'll know exactly what 70% looks like in your bowl — and you'll add water by eye, not by scale, because every batch of flour absorbs slightly differently. That's how professional bakers work. Hydration percentages are training wheels; they're how you learn the language. Once you speak it fluently, the numbers become a check rather than a recipe.
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