How to Calculate Sourdough Hydration by Hand

Hydration percentage is one of those numbers that sounds more complicated than it is. Once you understand what it means and how to calculate it, you’ll use it constantly: to compare recipes, to adjust dough feel, to troubleshoot a batch that came out too tight or too slack, and to communicate clearly with other bakers about what you’re making.

Here’s exactly how the math works, how to use it in practice, and what different hydration levels actually mean for your dough.

What Hydration Percentage Means

Sourdough hydration is the ratio of water weight to flour weight in a recipe, expressed as a percentage. That’s it. The formula is:

Hydration (%) = (water weight / flour weight) x 100

If a recipe uses 500g of flour and 375g of water, the hydration is 375 divided by 500, multiplied by 100. That gives you 75%. This is called a 75% hydration dough.

The percentage tells you how wet or dry your dough is relative to the flour. Higher percentages mean more water relative to flour, which produces a wetter, more open, more extensible dough. Lower percentages produce a stiffer, more structured dough that’s easier to shape by hand.

A Simple Worked Example

Here’s a basic sourdough recipe:

Bread flour: 450g
Whole wheat flour: 50g
Water: 375g
Starter: 100g
Salt: 10g

Total flour is 500g (450g + 50g). Water is 375g.

Hydration = 375 / 500 x 100 = 75%

That’s all there is to the basic calculation. You’re dividing water by flour and converting to a percentage.

When Your Recipe Has Multiple Flours

If your recipe blends different flour types, add them all together before calculating. The hydration percentage is always water against total flour, not against any single flour component.

So if you’re baking with 350g bread flour, 100g whole wheat, and 50g rye, your total flour is 500g. Use that 500g as the denominator in your hydration calculation regardless of the flour breakdown.

This matters because some bakers get confused when scaling or adapting recipes that use flour blends. The blend affects flavor, fermentation speed, and gluten development, but the hydration calculation stays the same: total water divided by total flour.

Accounting for Water in Your Starter

Here’s where the math gets slightly more involved, and where many home bakers stop short.

Your sourdough starter contains both flour and water. If you’re maintaining a 100% hydration starter (equal weights of flour and water), then 100g of starter contains roughly 50g of flour and 50g of water. Those contributions are part of your dough, but they often aren’t counted in a recipe’s listed hydration percentage.

The simplified hydration calculation above ignores the starter’s contents entirely. For most home bakers, this is accurate enough and the difference is small. A recipe calling for 100g of starter out of a 1000g flour batch is contributing about 5% additional water, which shifts the true hydration by a few percentage points at most.

If you want true hydration, the calculation looks like this:

True hydration = (recipe water + water in starter) / (recipe flour + flour in starter) x 100

For a 100% hydration starter, split the starter weight evenly: half is flour, half is water.

Using the earlier example with 100g of starter:

Recipe flour: 500g + 50g (from starter) = 550g total
Recipe water: 375g + 50g (from starter) = 425g total
True hydration: 425 / 550 x 100 = 77.3%

The difference between 75% and 77.3% is real but modest. Whether it matters depends on how precisely you want to hit a target hydration. For everyday baking, the simplified version is fine. For dialing in a specific formula or comparing recipes precisely, true hydration gives you a more accurate picture.

What Different Hydration Levels Feel Like

Numbers are useful, but hydration levels also have a physical character that experienced bakers recognize immediately. Here’s a rough guide to what you’ll encounter:

60 to 65%: Stiff dough, easy to handle, holds its shape well. Common in bagels and some hearth loaves. Forgiving and beginner-friendly but produces a tighter, denser crumb.

68 to 72%: Firm but pliable. This is a comfortable starting range for beginners who want an open crumb without fighting a wet dough. Holds shape through shaping and scoring without much trouble.

73 to 78%: The sweet spot for most country-style sourdough loaves. Dough is tacky and requires confident handling, but produces excellent oven spring and an open crumb. This is where most well-known sourdough recipes land.

80 to 85%: Noticeably wet and extensible. Requires technique: bench scrapers, wet hands, deliberate shaping. Produces very open crumb when fermented and handled correctly. Less forgiving of mistakes.

Above 85%: Challenging territory. Some bakers work in this range intentionally for ultra-open crumb structures, but it demands experience and often specialized techniques like coil folds and careful vessel support during final proof.

If you’re adjusting your own formula or experimenting with different targets, the CrumbDesk Hydration Calculator lets you enter your flour weight and target percentage and instantly see exactly how much water you need.

Adjusting Hydration in an Existing Recipe

Once you can calculate hydration, you can adjust it deliberately. This is useful when a recipe you’re working from produces dough that’s harder to handle than you’d like, or when you want to push toward a more open crumb.

To lower hydration: Reduce the water weight. If you’re at 78% and want to drop to 74%, calculate 74% of your flour weight and use that as your new water quantity. With 500g flour, 74% hydration means 370g of water instead of 390g.

To raise hydration: Add water gradually, not all at once. Increase by 2 to 3 percentage points at a time and observe how the dough handles before pushing further. Jumping from 72% to 82% in one bake is a recipe for a frustrating handling experience.

To hold everything else constant while adjusting hydration: Only change the water weight. Keep your flour, starter, and salt exactly the same. This isolates the hydration variable so you can clearly see and feel the difference.

If your batch size changes at the same time you’re adjusting hydration, the CrumbDesk Recipe Scaler can handle both adjustments at once, scaling your quantities to a new flour weight while maintaining your target hydration percentage throughout.

Whole Grain Flours and Hydration

Whole wheat, rye, and other whole grain flours absorb more water than white bread flour. A dough made with a significant percentage of whole grain flour will often feel stiffer than the hydration number suggests, because the bran and germ are soaking up water that would otherwise contribute to dough extensibility.

If you’re substituting whole grain flour into a recipe that was developed with white flour, you may want to increase hydration slightly to compensate. A common starting point is adding 5 percentage points of hydration for every 20% of whole grain flour you introduce. So a recipe that was 75% hydration with 100% white flour might become 80% hydration when you swap in 20% whole wheat.

This is a rough guide, not a fixed rule. Different whole grain flours absorb differently, and fresh-milled flours behave differently from commercially milled whole wheat. The only reliable calibration is observation: mix the dough, feel it, and adjust next time.

This also connects to your fermentation planning. Whole grain flours ferment faster due to higher enzyme activity and more available nutrients for your starter. If you’re increasing whole grain content, keep a close eye on your bulk fermentation window. The CrumbDesk Bulk Fermentation Calculator accounts for the variables that affect timing, which is especially useful when you’re working with a formula you’re still dialing in.

A Note on Starter Hydration

Your starter has its own hydration, separate from your dough’s hydration. A starter fed with equal weights of flour and water is a 100% hydration starter. A stiffer starter fed with more flour than water is below 100%.

Most home bakers maintain 100% hydration starters because the math is simple and the behavior is predictable. If you ever switch to a stiffer or more liquid starter, remember to account for the different water contribution when calculating your dough’s true hydration.

The CrumbDesk Starter Feeding Calculator can help you keep track of your starter’s hydration and feeding quantities, which makes the true hydration calculation for your dough much easier to run.

Hydration is one of those numbers that quickly becomes second nature. After a few bakes where you’ve consciously tracked it, you’ll start to feel the percentage before you even do the math. You’ll mix a dough, note how it moves in the bowl, and have a good intuition for whether you’re in the 72% range or the 78% range before you check your notes.

If you want to skip the arithmetic and just get the numbers right, the CrumbDesk Hydration Calculator will calculate your hydration percentage from your ingredients, or work backward from a target percentage to tell you exactly how much water to use.

FAQ

What is a good hydration for beginner sourdough bakers? Most beginners do well starting between 70 and 74%. The dough is workable, holds its shape, and still produces a reasonably open crumb with proper fermentation. Once you’re comfortable handling dough at that range, you can experiment with pushing higher.

Does hydration percentage affect flavor? Indirectly, yes. Higher hydration doughs ferment slightly faster and can develop flavor differently than stiffer ones. The more significant flavor factors are fermentation time and temperature, starter health, and flour type. But hydration does influence crumb structure, which affects how flavor is perceived in the final loaf.

Why does my dough feel wetter than the hydration percentage suggests? A few things can cause this. Whole grain flours that haven’t fully hydrated yet will release their absorbed water as mixing and resting continue, making the dough feel progressively slacker. High ambient temperatures soften gluten and make dough feel looser. And some flour brands absorb water differently than others. If your dough consistently feels wetter than expected, try a lower hydration by 2 to 3 percentage points and see if it improves.

Is it better to have higher or lower hydration? Neither is universally better. Higher hydration doughs can produce more open crumb structures and better oven spring when handled well. Lower hydration doughs are easier to shape, more forgiving, and still produce excellent bread. The best hydration is whatever produces the result you want at a skill level you can execute consistently.

How do I calculate hydration if I don’t have a scale? You really need a scale for this. Volume measurements are too inconsistent for hydration calculations to be meaningful. A cup of flour can vary by 20 to 30 grams depending on how it was scooped, which would throw your calculation significantly. A basic kitchen scale is one of the most useful tools you can own for bread baking.

Does autolyse change the effective hydration of my dough? No. Autolyse (resting flour and water together before adding starter and salt) doesn’t change the total water or flour in the recipe, so the hydration percentage stays the same. What it does change is how thoroughly the flour has absorbed the water before mixing, which can make the dough feel more cohesive and easier to work with even at higher hydration levels.

Can I use the hydration percentage to compare recipes from different sources? Yes, and this is one of its most useful applications. Two recipes may list very different gram weights but have the same hydration percentage, which means the dough will behave the same way. Conversely, two recipes at different hydration percentages will produce noticeably different doughs regardless of how similar the ingredient list looks. Hydration is one of the first numbers to compare when you’re evaluating whether a new recipe will suit your skill level or baking goals.