Sourdough Hydration Calculator

What is a sourdough hydration calculator?

A sourdough hydration calculator works out the hydration of your dough as a baker’s percentage, or tells you exactly how much water to add to hit a target hydration. Hydration is simply the weight of water compared with the weight of flour: at 500 g flour and 375 g water, your dough is 75% hydration. The tool runs the same maths in both directions, so you can either check the hydration of a recipe you already have or build a new recipe around a hydration number you want.

Hydration is the single most useful figure in bread baking because it controls how the dough behaves and how the crumb turns out. Wetter dough (higher hydration) tends to give a more open, airy interior but is stickier and trickier to shape; drier dough (lower hydration) is firmer, easier to handle and produces a tighter crumb. Expressing water as a percentage of flour lets you compare recipes of any size and scale them cleanly from a single loaf to a full bake.

How does the sourdough hydration calculator work?

It uses one short relationship, applied in whichever direction you need:

hydration % = water ÷ flour × 100
water       = flour × target% ÷ 100

Terms and units. Flour and water are both measured by weight in grams — this is why bakers weigh ingredients on a scale rather than measuring by cup. Hydration is the result expressed as a percentage of the flour weight. A figure of 100% would mean equal weights of flour and water; 75% means the water is three-quarters of the flour weight.

The widget does the arithmetic both ways. In find hydration mode you enter flour and water, and it returns water ÷ flour × 100. In find water mode you enter flour and a target hydration, and it returns flour × target ÷ 100. Flour, water and the target must all be positive numbers; a zero or blank flour entry has no valid answer and prompts you to fix it.

A handy way to read it: hydration is the percentage of the flour’s weight that you are adding as water. So at 70% hydration, every 100 g of flour gets 70 g of water — and at 1000 g of flour that is 700 g of water.

Examples

Every example below matches the tool exactly: hydration % = water ÷ flour × 100, or water = flour × target ÷ 100.

Example 1 — find hydration (500 g flour, 375 g water)

• hydration = 375 ÷ 500 × 100 = 75%
• A balanced, popular sourdough hydration that is open but still manageable.

Example 2 — find water for a target (500 g flour, target 75%)

• water = 500 × 75 ÷ 100 = 375 g
• The reverse of Example 1: it gives back exactly the water that produces 75%.

Example 3 — find water at a lower target (1000 g flour, target 70%)

• water = 1000 × 70 ÷ 100 = 700 g
• A firmer dough that is easier to shape, good for batards and sandwich loaves.

Example 4 — find hydration of a wetter dough (1000 g flour, 800 g water)

• hydration = 800 ÷ 1000 × 100 = 80%
• A high-hydration dough for an open, airy crumb but stickier handling.

Notice that Examples 1 and 2 are mirror images of each other: finding hydration from 500 g and 375 g, then finding water from 500 g and 75%, both circle back to the same pair of numbers.

Common hydration reference

These are the hydration levels most sourdough bakers work in. “Water per 1000 g flour” is computed the same way the tool does (1000 × target ÷ 100) so you can sanity-check the widget at a glance.

Hydration	Dough feel	Water per 1000 g flour	Typical use
65%	Firm, easy to shape	650 g	Beginner loaves, bagels, tight crumb
70%	Slightly tacky	700 g	Everyday sourdough, sandwich loaves
75%	Soft, supple	750 g	All-round artisan loaf, open crumb
80%	Wet, sticky	800 g	Open, airy crumb, ciabatta-style
85%	Very wet, slack	850 g	Highly open crumb, advanced handling

Most home sourdough lives in the 70% to 78% band, which balances an open crumb against dough that is still possible to shape by hand. Treat these as starting points — flour type, protein content and ambient humidity all shift how a given hydration feels.

Common uses

• Checking a recipe: type the flour and water from a recipe to see its true hydration before you commit.
• Building from a target: decide you want 75%, enter your flour, and read off the exact water to weigh.
• Scaling a bake: keep the hydration fixed and change the flour to move from one loaf to several.
• Comparing recipes: convert two recipes to percentages to see which is wetter, regardless of batch size.
• Adjusting for flour: dial hydration down a few points for lower-protein flour, or up for thirsty whole-grain.
• Beginner safety net: start nearer 68% to 70% for dough that is forgiving to shape, then climb as you gain confidence.

Tips and common mistakes

• Weigh, don’t measure by volume. A cup of flour can vary widely in weight, which throws off hydration. A scale is what makes the percentage meaningful.
• Higher is not automatically better. High hydration gives open crumb but is harder to handle; match the number to your skill and your flour.
• Whole grains drink more water. Whole-wheat and rye absorb more, so the same percentage feels drier than with white flour — you may need to nudge hydration up.
• Remember the starter. This tool figures dough hydration from the flour and water you enter; if you want total hydration, add the flour and water inside your starter too.
• Add water gradually. Hold back a little of the calculated water and add it during mixing, especially at high hydration, so you do not overshoot into an unworkable batter.
• Percent, not weight, defines the dough. 375 g + 500 g and 750 g + 1000 g are both 75%; the feel is the same at different scales.

Limitations and notes

This calculator handles the hydration maths only — the ratio of water to flour by weight. It does not account for the flour and water locked inside your sourdough starter, salt, oil or other add-ins, so the figure it returns is the hydration of the flour and water you enter rather than a full formula total. For a true overall hydration you would fold the starter’s flour and water into the totals first. The right hydration also depends on your flour’s protein and the day’s humidity, so the reference band above is a launch point, not a rule.

Results follow directly from the numbers you type, and flour, water and the target must be positive numbers or the tool will ask you to correct the entry. Everything runs privately in your browser — no weights, recipes or percentages are sent to a server or stored anywhere.

For more kitchen maths, try the pizza dough calculator, the recipe scaler and the water-to-rice ratio calculator on the cooking category page.