ToolNestFree Sourdough Hydration Calculator
Last updated: October 20, 2026
Quick answer: Hydration is the soul of sourdough — it decides whether your crumb is open and airy or tight and dense. But most calculators get the math wrong by ignoring the flour and water already hiding in your starter. This free sourdough hydration calculator is starter-aware: tell it your flour, starter weight, and starter hydration, and it computes exactly how much water to add for your target hydration — plus a full baker's-percentage table and total dough weight. Everything runs in your browser; no signup, no ads.
🔒 100% Private: Data never leaves your device.
Tip: hold back 20–30 g of water and add it during mixing if the dough feels right — flour absorbs differently by brand and season.
✓ Free forever · ✓ No signup · ✓ Tool inputs stay in your browser — never sent to our servers.
How to Use the Sourdough Hydration Calculator
- Pick a mode: 'Target hydration → water' tells you how much water to add; 'Water → actual hydration' tells you the hydration of the water you're about to use.
- Enter your flour weight, starter weight, and your starter's hydration (100% means equal parts flour and water).
- Enter your target hydration — or your planned water amount — and your salt percentage (2% is standard).
- Click Calculate: you get the exact water to add, the true total hydration, a baker's-percentage table, and total dough weight.
- Adjust and recalculate freely — the math updates instantly, so dial in your formula before you mix.
Why Use Our Sourdough Hydration Calculator?
- Starter-aware math — the flour and water inside your starter are counted, so the hydration number is the true total, not a rough guess.
- Two directions — solve for the water you need, or check the hydration of the water you planned.
- Baker's percentages — every ingredient expressed as a percentage of total flour, the professional baker's standard.
- Salt + dough weight — salt at your chosen percentage and the final dough weight, ready for dividing into loaves.
- 100% private — runs entirely in your browser; your recipes never leave your device.
Common Use Cases
- Dial in a new recipe: Start at 72–75% hydration, bake, then nudge up or down — the calculator keeps the math exact as you iterate.
- Scale a recipe up or down: Keep baker's percentages fixed and the tool rescales flour, water, starter, and salt proportionally.
- Convert a recipe to baker's %: Paste a friend's cup-and-spoon formula into grams, and the calculator reveals the true hydration hiding inside.
- Troubleshoot a gummy crumb: Check whether your actual hydration (including the starter's water) was higher than you thought — the usual culprit.
- Teach a baking class: Show students live how changing starter hydration from 100% to 80% shifts the water needed — arithmetic they can see.
- Adapting a book recipe to your flour: A formula written for strong Canadian flour at 76% hydration may need 72% with your local all-purpose — dial the target down, hold back water, and iterate once instead of baking three sticky loaves.
- Comparing two recipes before baking: Two authors' '72% hydration' loaves can differ wildly once the starter's water is counted. Run both through the calculator to see which one is really wetter before committing six hours of your Saturday.
- Cutting starter for a longer cold retard: Want an 18-hour fridge ferment instead of 12? Drop starter from 20% to 10–12% and the calculator keeps hydration — and salt — exactly where they were.
Sourdough Hydration Calculator vs Alternatives
- Recipe blogs with fixed formulas: Great for a first bake, but a fixed '350 g water' can't adapt to your flour. Ours recalculates for any flour, starter, or hydration.
- Bread-baking apps: Handy for timers and journals. For the arithmetic itself — especially the starter correction — a calculator that shows every number is faster than an app's journal screen.
- Spreadsheet calculators: Accurate if you build the starter correction yourself — most don't. This does the correction automatically in one click.
- Asking in r/Breadit: The community is wonderful for technique, but for arithmetic a calculator is faster — and never argues about 73% vs 75%.
- Printed hydration charts: Charts in baking books give water for round flour weights — handy at 500 g, useless at 735 g or with a stiff 80%-hydration starter. Ours computes your exact numbers for any inputs.
- Asking an AI chatbot: Chatbots can walk through the formula, but arithmetic isn't their strong suit — one slipped digit and your '75%' is really 79%. A purpose-built calculator applies the same formula correctly every time.
If you bake the same formula every week, memorize it and skip the calculator. For everything else — new flours, recipe conversions, class demos, scaling — starter-aware math in one click beats mental arithmetic and beats the calculators that pretend your starter is pure flour.
Frequently Asked Questions
What is sourdough hydration?
Hydration is water weight divided by flour weight, times 100 — baker's percentage with flour always at 100%. A 500 g flour / 375 g water dough is 75% hydration. Crucially, the water inside your starter counts: a 100 g starter at 100% hydration already holds 50 g of flour and 50 g of water, and honest hydration math includes both.
What hydration should I aim for as a beginner?
Start around 70–72%. Lower-hydration dough is easier to shape and score, and forgiving flour still gives a lovely crumb. As your handling improves, push toward 75–80% for a more open crumb — the calculator shows exactly how much extra water each point costs.
Does starter hydration change the math?
Yes, and it's the part most calculators skip. A 100 g starter at 100% hydration contributes 50 g flour + 50 g water; at 80% hydration it contributes ~56 g flour + ~44 g water. That 6 g difference in flour shifts your true hydration by over a point — this calculator applies the correction automatically.
Why is my dough stickier than the recipe's hydration suggests?
Three usual suspects: (1) your starter held more water than you counted, (2) your flour absorbs less than the recipe author's, or (3) warm kitchens speed fermentation and slacken dough. Use 'Water → actual hydration' mode to see the true number, then hold back 20–30 g of water next bake and add it only if the dough asks for it.
What is baker's percentage?
A system where every ingredient is expressed as a percentage of the total flour weight (flour = 100%). Salt at 2%, water at 75%, starter at 20% — it makes recipes trivially scalable and comparable. The table on this page gives you the full breakdown for your formula.
How much salt goes in sourdough?
The standard is 2% of total flour weight — 10 g for 500 g of flour. Below ~1.8% bread tastes flat; above ~2.2% it can inhibit fermentation. This calculator applies your chosen percentage to the total flour including the starter's share, which is the correct base.
How should I adjust hydration for whole wheat or rye flour?
Different flours drink water differently. Whole wheat typically needs 2–5 points MORE hydration than white flour — bran absorbs slowly, so the dough feels dry at first and then loosens (don't judge it during the first 10 minutes). Rye goes the other way: it absorbs fast but can't build gluten, so rye-heavy recipes run 5–8 points LOWER than a comparable white loaf. Enter the flour you're actually using, hold back 20–30 g of water, and let the dough — not the number — have the final word.
Does an autolyse change the hydration calculation?
No — an autolyse (resting flour and water before adding starter and salt) uses the same total water, so the hydration math doesn't change. What changes is handling: fully hydrated flour at 78% feels dramatically more manageable after a 30–60 minute autolyse than right after mixing. If high hydration scares you, keep the water and add the rest.
My recipe is in cups, not grams — can I still use this calculator?
Convert to grams first, because cups are the real problem: one 'cup' of flour can weigh anywhere from 120 g to 150 g depending on how you scoop, which swings hydration by 10+ points. Weigh the flour once on a kitchen scale (they cost under $15) and enter grams. Grams in, honest hydration out — cup measurements can't give you that.
What do different hydration levels actually look like?
Roughly: 60–65% is stiff and bagel-like — very easy to shape; 68–72% is the beginner sweet spot — soft but manageable; 73–78% is the classic artisan range with an open, airy crumb; 80%+ is ciabatta territory — slack, sticky, and hard to shape, best handled with wet hands and coil folds. The 'Water → actual hydration' mode tells you exactly which band your recipe sits in.
Does hydration affect how fast my dough ferments?
Yes — wetter dough ferments faster. Enzymes and yeast move more freely at high hydration, so an 80% dough can finish bulk fermentation 20–30% sooner than a 68% dough with the same starter amount and temperature. If you raise hydration, watch the dough (volume growth, jiggle, bubbles on top) rather than the clock.
How do I handle high-hydration dough without it sticking to everything?
Wet your hands before every touch — water beats flour on the hands for sticky dough. Use coil folds instead of stretch-and-folds for structure, keep bench flour minimal (it just gets absorbed and toughens the crust), and shape decisively: a confident, quick pre-shape beats a long, flour-dusted wrestling match. And as noted above, a 30–60 minute autolyse tames stickiness before it starts.