Sourdough Bread Calculator

What do I need to know about Baker's Percentages?

All ingredients are expressed as a percentage of total flour weight. Water at 75% = 75g per 100g flour. Starter at 20% = 20g per 100g flour. This makes scaling any recipe straightforward while keeping relationships between ingredients constant.

What's the key thing to understand about Starter Hydration Adjustment?

Your starter contributes both flour and water to the dough. A 100% hydration starter (equal flour and water by weight) means the starter is 50% flour, 50% water. This calculator adjusts for starter hydration, so the final dough hits your target hydration precisely.

What's the key thing to understand about Hydration Guide?

65–70%: easier to handle, tighter crumb — good for beginners. 75–80%: open crumb, slightly sticky. 80–85%: very open crumb, requires good technique (bench scraping, stretch and fold). Above 85%: extremely challenging, for experienced bakers only.

What's the key thing to understand about Food Safety Fundamentals?

Food safety rules apply regardless of cooking method or time. The danger zone for bacterial growth is 4-60 degrees C — food should not remain in this range for more than 2 hours. Core temperature targets: poultry 75 degrees C throughout (no pink allowed), pork 75 degrees C, beef/lamb can be pink when above 63 degrees C (due to surface-only bacteria on whole cuts). Never use the same equipment for raw and cooked food without washing. Leftovers should be cooled rapidly (within 2 hours), refrigerated promptly, and used within 3-4 days, or frozen for longer storage. When reheating, food should reach 75 degrees C throughout, and should only be reheated once.

What should I know about Inoculation Rate (Starter %)?

The starter_pct input in this calculator — sometimes called the inoculation rate — controls how much active starter you're adding relative to the total flour in the final dough, and it has a big effect on both fermentation speed and final flavor. A higher inoculation rate (commonly 15–20% or more) introduces a larger population of yeast and bacteria, so the dough rises faster and is well suited to same-day baking, but can sometimes produce a more sour, less structured crumb if the dough overferments before shaping. A lower inoculation rate (as little as 1–5%) means a much slower rise, which is exactly what's wanted for an overnight cold retard in the fridge, and often develops a more complex, balanced flavor over the longer fermentation window. There's no single "correct" percentage — it's a scheduling and flavor choice as much as a technical one — but it's worth knowing that doubling the starter_pct won't simply double the dough's rise speed in a linear way, since fermentation rate also depends heavily on dough temperature and the starter's own vigor at the time it's used.

What should I know about Why Starter Hydration Matters for This Calculator?

Because a sourdough starter is itself a mixture of flour and water, it carries its own hydration into the final dough, and this calculator needs to account for that to report an accurate true hydration. If your starter is kept at 100% hydration (equal parts flour and water by weight, the most common default), half of every gram of starter you add is flour and half is water. A starter maintained stiffer, say at 50% hydration, contributes proportionally more flour than water for the same total weight. This is exactly why the calculator asks for starter_hydration separately from the overall target hydration input, and why the actual_hydration output can differ meaningfully from the hydration percentage you originally typed in — the flour_g and water_g outputs are deliberately calculated as the flour and water needed in addition to what the starter itself is already contributing, so that the finished dough lands on your real target hydration once everything is combined, not just the non-starter portion.

What do I need to know about Scaling a Sourdough Recipe Up or Down?

Scaling a sourdough recipe to a different final dough weight or different tin size is done by keeping every ingredient's baker's percentage constant relative to the flour, then recalculating each ingredient's weight from the new target flour weight. First work out the total of all baker's percentages (flour at 100%, plus water, salt, and starter percentages added together) to get the dough's total percentage; divide the desired final dough weight by this total to find the weight represented by each 1%; then multiply that figure by each ingredient's own percentage to get its scaled weight. For example, scaling up to fill two loaf tins instead of one roughly doubles the target dough weight, so every ingredient simply doubles too, since percentages don't change with scale. The one adjustment that doesn't scale linearly is fermentation time: a larger batch of dough retains heat differently and ferments at a very slightly different rate than a smaller one of the same hydration and temperature, though in practice this difference is small enough that most home bakers can use the same timing guide regardless of batch size, checking the dough's appearance and the float/poke test rather than relying purely on the clock when scaling significantly.

What's the Difference Between Baker's Percentage and Total Dough Weight?

Baker's percentage expresses every ingredient as a percentage of the total flour weight (flour is always 100%), which makes a recipe instantly scalable to any batch size — a formula of 100% flour, 70% water, 20% starter, 2% salt describes the same bread whether you're making one small loaf or ten. Total dough weight, by contrast, is simply the sum of every ingredient's actual weight, which is what you need to know to decide how many loaves a given amount of dough will make, or to scale a recipe to fit a specific tin or banneton. The two systems work together: baker's percentage defines the recipe's proportions, and total dough weight (divided by the sum of all the percentages, i.e. total% ÷ 100, to find the flour weight, then multiplying each ingredient's percentage by that flour weight) converts those proportions into the actual grams needed for a specific batch size.

Worked Example: Full Baker's Percentage Breakdown for Two 900g Loaves

Target: two loaves at 900g finished dough weight each = 1,800g total dough. Using a formula of flour 100%, water 70%, starter 20% (at 100% hydration), salt 2% — total percentage = 100+70+20+2 = 192%. Flour weight = total dough weight ÷ (total% ÷ 100) = 1,800 ÷ 1.92 ≈ 937.5g. From there: water = 937.5 × 0.70 ≈ 656g, starter = 937.5 × 0.20 ≈ 187.5g, salt = 937.5 × 0.02 ≈ 18.75g. Checking the total: 937.5 + 656 + 187.5 + 18.75 ≈ 1,799.75g, matching the 1,800g target (small rounding). Note the starter itself is roughly half flour and half water (at 100% hydration), so the true total flour in the dough is slightly higher than 937.5g once the starter's flour content is folded in — professional formulas sometimes separate this out explicitly as 'true hydration' for precision, though for home baking the simplified version above is normally close enough.

Why Is Raw Flour and Raw Dough a Food Safety Concern?

Flour is a raw agricultural product that has not been heat-treated, and it can occasionally carry harmful bacteria such as E. coli or Salmonella picked up during growing or milling — this is why food safety authorities including the FDA and CDC specifically warn against eating raw dough or batter, and against letting children play with raw dough as if it were a safe toy. This applies to sourdough starter and dough just as much as any other flour-based dough: the fermentation process and the acidity a sourdough starter develops are not reliably sufficient to eliminate these pathogens, and only full baking to a safe internal temperature makes the bread safe to eat. Fully baked sourdough bread, reaching a high internal crust and crumb temperature well above any pathogen's survival range during a normal bake, carries none of this risk — the caution applies specifically to tasting raw dough, batter, or unbaked starter discard, not to finished baked bread.