Baker's percentages, hydration ratios, and recipe scaling — get exact flour, water, starter, and salt for any batch size.
Baker's percentage is a ratio system where every ingredient in a bread recipe is expressed as a percentage of the total flour weight. Flour is always 100% by definition. If a recipe calls for 500 grams of flour and 375 grams of water, the hydration is 75% (375 ÷ 500 × 100). If it calls for 10 grams of salt, the salt is 2%. This might seem like an unnecessary abstraction when you could just follow a recipe, but baker's percentage transforms bread baking from a rigid procedure into a language you can fluently read, scale, and compare.
The practical benefit becomes obvious the moment you want to double a recipe, bake a single test loaf from a recipe designed for a commercial mixer, or compare two recipes to understand why one produces a more open crumb than the other. Because every percentage is anchored to flour, you can scale any recipe up or down by simply changing the flour weight and multiplying everything else by the same factor. A recipe written in baker's percentages works equally well for a 300-gram test loaf or a 5-kilogram batch. This is how professional bakers at every scale — from artisan bakeries to industrial operations — think and communicate about bread.
For sourdough specifically, baker's percentage also lets you understand and deliberately control the relationship between your starter, hydration, and salt in a way that intuitive recipes obscure. When a recipe says "1 cup of starter," you have no idea what that means for fermentation speed or flavor unless you know how much flour is in the cup. When a recipe says "20% starter," you know immediately that fermentation will proceed at a standard pace, that the starter contributes a meaningful amount of pre-fermented flour to the dough, and that you can back-calculate how long bulk fermentation will take based on your kitchen temperature.
Hydration is the single most influential variable in sourdough baking after starter health. At 65–70%, a sourdough dough is stiff enough to hold its shape with minimal effort. It tolerates beginner shaping technique, proofs predictably, and bakes into a dense, chewy crumb that most people recognize as a classic country loaf. This range is ideal for first-time sourdough bakers or anyone making sandwich bread that needs to slice cleanly. At 72–78%, which is the most common range in recipes published by experienced home bakers, you get a dough that is tacky but manageable, requires stretch-and-fold technique during bulk fermentation, and produces the trademark uneven, open crumb with irregular holes that defines artisan sourdough. From 78–85%, the dough becomes genuinely wet and slack. Shaping requires a confident hand, a well-floured surface, and a good banneton to hold the structure during proofing. The reward is a very open crumb with large, irregular holes. Above 85%, you are in the territory of ciabatta-style loaves — the dough may be baked in a pan or shaped with a bench scraper rather than hands, and the results can be spectacular, but the margin for error collapses significantly.
Starter percentage controls fermentation speed and acidity. A small amount of starter — 5 to 10% of flour — means very few wild yeast cells and bacteria relative to the total dough mass. Fermentation proceeds slowly, giving those organisms time to produce more acetic acid, which produces the sharp, vinegary sourness associated with San Francisco-style sourdough. Using 15 to 20% starter is the standard approach for everyday baking: it ferments fast enough to bake on the same day, produces a balanced tang, and is forgiving of minor temperature swings. At 25 to 30%, bulk fermentation moves quickly — useful in cold kitchens or when you are short on time — but the short fermentation window means less flavor development and a less sour loaf. Salt does more than add flavor: it tightens gluten structure, slows fermentation slightly by inhibiting yeast activity, and extends the window of time during which the dough behaves predictably. The standard 2% salt is calibrated to balance flavor and fermentation timing. Dropping below 1.8% weakens gluten and accelerates fermentation; rising above 2.2% adds a saltier flavor and slows the rise noticeably.
Autolyse is a technique where you mix flour and water together and let them rest — without starter or salt — for 30 minutes to 2 hours before completing the dough. During this rest, the flour fully hydrates and gluten networks begin forming on their own, driven by enzymes naturally present in the flour. The result is a dough that is smoother, more extensible, and easier to develop without heavy mechanical mixing. Autolyse is especially useful at higher hydrations (above 75%) where the dough can be difficult to develop by hand, and with whole grain flours that need extra time to fully absorb water. To use autolyse, simply combine your recipe's flour and water, mix until no dry flour remains, cover, and rest. Then add your starter and salt and continue with the recipe. Salt is always added after autolyse, never during — it would interfere with the enzymatic activity that makes the technique work.
Bulk fermentation is the first rise, starting the moment you finish mixing your dough and ending when you shape it. During bulk fermentation, wild yeast produces carbon dioxide that inflates the dough, and lactic acid bacteria produce acids that develop flavor and strengthen gluten. At 70°F (21°C) with 20% starter, a standard bulk fermentation takes roughly 4 to 6 hours. At 75°F it compresses to 3 to 4 hours; at 65°F it can stretch to 8 or more hours. The most reliable signal that bulk fermentation is complete is not the clock but the dough itself: it should increase in volume by 50 to 75%, feel airy rather than dense when you press it, and have a slightly domed top when you look at it through the side of a clear container. A dough that has over-fermented — gone past the peak — becomes slack, sticky, and nearly impossible to shape. An under-fermented dough will be dense and lack the spring in the oven that produces a good crust. The Fermentation Calculator can help you track timing for other fermented foods alongside your bread schedule.
After bulk fermentation comes shaping and then proofing, also called the final proof or second rise. Proofing is the shorter, final fermentation period after the dough has been shaped and placed in a banneton, loaf pan, or couche. Proofing allows the shaped dough to relax, recover some of the gas lost during shaping, and develop additional flavor before baking. A room-temperature proof typically takes 1 to 3 hours. Cold proofing — placing the shaped dough in the refrigerator overnight for 8 to 16 hours — is favored by many home bakers because it slows fermentation to a crawl, makes scoring much easier on cold dough, and deepens the sour flavor by encouraging acetic acid production at cool temperatures. Cold-proofed loaves also tend to have better oven spring because the yeast activity resumes aggressively when the cold dough hits a hot oven.
A sourdough starter is a live culture of wild yeast and lactic acid bacteria maintained in a mixture of flour and water. Keeping it healthy requires regular feeding — discarding a portion of the old starter and adding fresh flour and water — which prevents the accumulation of too much acid and keeps the microbial population fed and active. For everyday baking, a 1:1:1 ratio works well: 1 part starter to 1 part flour to 1 part water by weight. A starter that has been fed and is ready to use — at peak activity — will have doubled in volume since its last feeding, smell pleasantly yeasty and mildly sour, and pass the float test: a small spoonful dropped into water will float briefly because of the gas trapped inside. If you do not bake every day, you can store your starter in the refrigerator and feed it once a week. Pull it out 4 to 8 hours before baking, feed it, and let it rise to peak at room temperature before using it in your dough.
Scoring — making deliberate cuts in the surface of the proofed dough just before baking — is not merely decorative. It controls where the dough expands during baking, preventing random blowouts along the sides and directing expansion upward for maximum oven spring. Use a sharp lame (a razor blade on a handle designed for bread scoring), a sharp knife, or a razor blade held at a 30- to 45-degree angle. A single long slash down the center of an oval loaf is the classic starting point. More elaborate patterns — ears, wheat stalks, crosshatches — require a fast, confident stroke and a properly cold, taut dough surface. Score too shallow and the cuts seal before the loaf can expand. Score too deep and the dough collapses slightly before it has a chance to spring. Aim for cuts about half an inch deep. Cold dough from an overnight refrigerator proof scores more cleanly than room-temperature dough.
The Dutch oven is the home baker's best substitute for a professional deck oven with steam injection. Sourdough needs steam during the first 20 minutes of baking: steam keeps the crust soft and extensible long enough for the loaf to fully expand before the crust sets. A Dutch oven traps the steam produced by the dough itself, creating exactly that humid environment. Preheat your Dutch oven empty inside your oven at 500°F (260°C) for at least 30 to 45 minutes. Gently lower the scored, cold-proofed dough into the scorching pot, cover it, and bake for 20 minutes with the lid on. Then remove the lid and reduce the temperature to 450°F (232°C) and bake for another 20 to 25 minutes until the crust is deep mahogany brown and the internal temperature reaches at least 205°F (96°C). A pale sourdough crust is an under-baked one — the Maillard reaction and caramelization that give sourdough its deep flavor happen at high temperatures, and most home bakers stop too early.
Dense sourdough has a small number of likely causes, and most of them come down to fermentation. The most common is an inactive or under-fed starter: if your starter does not reliably double in volume after a feeding at room temperature, it is not strong enough to leaven a loaf. Feed it twice a day for several days, use warmer water (80°F / 27°C), and bake with it only at peak activity. Under-fermented bulk fermentation is the second most common culprit — if your dough has not risen by at least 50% and does not feel airy and slightly jiggly, it needs more time. Poor gluten development produces a structure that cannot hold the gas the yeast produces — this is solved by consistent stretch-and-fold sessions during bulk fermentation and proper shaping tension. Finally, under-baking traps moisture in the crumb and creates a gummy, dense interior even when the outside looks done. Always verify the internal temperature with a thermometer. For troubleshooting your kitchen environment and process, also see our Fermentation Salt Calculator for related live-culture food projects, and our Food Storage Calculator if you plan to build a longer-term pantry baking supply.