Sourdough Baker’s Percentage Calculator

About this calculator

Calculate sourdough baker’s percentages, total hydration and prefermented flour. Scale dough and explore ingredient, levain and dough-temperature tools.

How to use the sourdough calculator

Start with flour or a target dough weight. Set the flour blend, final-mix water, levain, salt and optional inclusions. Edit either percentage or grams: the last field you edit drives that ingredient. Values entered in grams stay fixed while other inputs change. The summary pauses when a formulation is invalid, rather than showing an old recipe.

Use the final-mix list when weighing ingredients. Scale buttons multiply the current recipe, including gram-entered ingredients, while preserving ratios. Changing mode also preserves the formulation. Loaf planning switches to target-dough mode; its editable plan is separate from later scaling changes. Reset restores the worked recipe; optional planning tools keep their own settings.

What are baker’s percentages?

Total flour is all flour in the dough, including flour inside the levain, and is always 100%. An ingredient at p% weighs total flour × p / 100. Salt and inclusions use this denominator. Levain percentage has a different label: prefermented flour %, not whole starter mass %.

Simple hydration vs true hydration

Simple hydration = separately added water ÷ separately added flour × 100. Both exclude levain. True hydration = (separately added water + levain water) ÷ total flour × 100. The editable water percentage is separately added water ÷ total flour, so it is deliberately labeled “% of total flour”; it is not either hydration metric when levain is present.

For total flour F, prefermented fraction p and levain hydration fraction h: levain flour = Fp, levain water = Fph, final-mix flour = F(1 − p). True hydration as a fraction is final-water fraction + ph; simple hydration is final-water fraction ÷ (1 − p).

Prefermented flour and starter hydration

Prefermented flour is the levain’s flour divided by all flour. A levain weighing L at hydration h contains L ÷ (1 + h) flour and the remainder water. At 100% hydration, 200 g levain contains 100 g of each. In a recipe with 1,000 g total flour that is 10% prefermented flour, but 20% whole levain by flour weight. Stiff and liquid levains change the water contribution.

Scale sourdough by dough weight

Dough mass = final-mix flour + final-mix water + whole levain + salt + inclusions. Equivalently it is total flour + all water + salt + inclusions. Levain flour is counted once. For percentage-driven quantities, dough = F × (1 + final-water fraction + prefermented fraction × levain hydration fraction + salt fraction + inclusion fractions).

When some ingredients are fixed grams, their mass is separated as C and the remaining flour coefficient as K. Target mode solves F = (target − C) ÷ K directly. Fixed whole levain contributes only its water to C because its flour is already inside F. Impossible targets are rejected. There is no iterative approximation or baking-loss adjustment.

Using multiple flours and inclusions

The flour blend describes total flour composition. Select one flour to supply all levain flour, including seed flour; its share must cover that amount. The final-mix list subtracts levain flour from that selected component. Mixed-flour starters need an equivalent single-component assumption or a future more detailed allocation model; this version cannot independently allocate several levain flours.

Flour shares must total 100% (within 0.0000001 percentage points of floating-point tolerance). Shares are never silently normalized. Add-ins contribute mass but no modeled flour or water, even for moist ingredients. Salt is editable from zero to 10%; that is a calculation bound, not dietary or recipe guidance. No numeric “typical salt” claim is made.

Levain builder methodology

Hydration mode splits the desired levain into flour and water, then subtracts the seed’s actual flour and water to find fresh additions. Negative additions are impossible and rejected. Ratio mode uses seed : fresh flour : fresh water, with 1:1:1, 1:2:2 and 1:5:5 presets. It calculates the resulting hydration from the seed composition; a non-100% seed does not magically become 100% hydrated.

The optional recipe link keeps desired amount and hydration synchronized with scaling. Seed amount stays your chosen value. Ratio mode is independent and does not show contradictory target controls. The builder does not estimate levain maturity or allow for transfer losses.

Fermentation planner assumptions

This is a heuristic schedule, not an equation predicting fermentation. The editable initial bulk window of 4–8 hours, folds at 30–120 minutes and 30-minute bench rest are project planning assumptions requiring empirical calibration. Bulk starts at mixing; folds happen during it. Cold-proof hours are a user preference. Temperature and recipe inoculation are recorded as context and do not automatically alter the hours.

Starter activity, flour, hydration, salt, dough and ambient temperatures, handling, and desired fermentation all matter. Assess dough rise, aeration and strength before shaping, and proof before baking; the clock alone cannot establish readiness. The Perfect Loaf’s bulk fermentation guide (opens in a new tab) supports this observation-based approach, not this project’s numerical windows. Reference reviewed September 25, 2026.

Times are integer minute offsets from the entered local start. +1 day and later labels handle midnight without Date objects or timezone conversion. This planning clock does not account for daylight-saving clock changes.

Desired dough temperature

For dough with preferment, water temperature = 4 × target dough temperature − flour temperature − room temperature − preferment temperature − friction adjustment. The four-factor convention follows King Arthur Baking’s Dough Temperature reference (opens in a new tab), reviewed September 25, 2026. Friction is an empirical adjustment for the mixing process, entered here as a Celsius temperature difference; zero explicitly omits that adjustment.

This professional rule of thumb is not a mass-weighted thermal model or guarantee. Measure actual dough temperature and calibrate. Results outside the project’s 0–50°C practical check band receive a neutral notice and are not clamped. The tool is for prefermented dough, not the separate three-factor straight-dough convention.

Worked sourdough example

The initial recipe has 1,000 g total flour: 800 g bread flour and 200 g whole wheat. With 10% prefermented flour assigned to bread flour and levain at 100% hydration, the levain is 200 g: 100 g flour + 100 g water. Weigh 700 g bread flour and 200 g whole wheat into the final mix, plus 650 g water, 200 g whole levain and 20 g salt.

Total dough is 1,770 g, or two 885 g portions. True hydration is 750 ÷ 1,000 = 75%; simple hydration is 650 ÷ 900 ≈ 72.22%; salt is 2%. No inclusions are present. At a target of 1,800 g with the same ratios, total flour becomes approximately 1,016.95 g. Tests cover this example and the physical ingredient sum.

Assumptions and limits

Use grams and Celsius. Total flour is 1–100,000 g and dough 1–200,000 g. Final water is 0–300% of flour, prefermented flour 0–95%, levain hydration 1–500%, salt 0–10%, and total inclusions 0–200%. Up to ten flour rows and ten inclusion rows are supported, with names of 1–60 characters. Use 1–100 whole loaves and 1–20,000 g per planned loaf, within the total dough limit.

Builder seed is 0.1–100,000 g, total levain up to 200,000 g, and seed hydration 1–500%. Planner temperatures are 5–40°C, bulk windows 2–24 hours and cold-proof preference 0–48 hours. DDT temperatures are 0–50°C with friction 0–20°C difference. These are input limits, not safety or optimal baking recommendations.

Native floating-point arithmetic is used; summary displays round to two decimals. Ingredient absorption, add-in moisture, fermentation mass changes and baking loss are not modeled. Biological timing and DDT are estimates. JavaScript is required for interaction. Recipes remain only in this tab’s memory: no saving, URL state, cookies, analytics or recipe transmission. Refresh resets the tool.

Sourdough calculator FAQ

What is baker’s percentage, and why is flour always 100%?

Baker’s percentage compares an ingredient’s weight with total flour, including levain flour. Flour is the reference, so all flour together is 100%; the whole recipe does not need to add up to 100%. With 1,000 g total flour, 2% salt means 20 g salt. Each flour in a blend is a share of that same total.

Why do the water percentage, simple hydration and true hydration differ?

The editable water percentage is final-mix water divided by total flour. Simple hydration divides that water by final-mix flour only. True hydration includes both the water and flour in the levain. In the worked recipe, 650 g added water, 900 g added flour and 200 g levain at 100% hydration give a 65% water entry, about 72.22% simple hydration and 75% true hydration. Use Apply true hydration to set the overall hydration; changing its target field alone does not apply it.

Does 10% prefermented flour mean 10% starter by weight?

No. Prefermented flour is levain flour divided by total flour. With 1,000 g total flour and 10% prefermented flour, the levain contains 100 g flour. At 100% levain hydration it also contains 100 g water, making 200 g whole levain. The Levain grams field means this whole mass, while its percentage field means prefermented flour.

What changes when I change the levain hydration?

At a fixed total flour and prefermented-flour percentage, levain flour stays fixed while its water and whole mass change. If you entered whole levain grams instead, that mass stays fixed and its flour/water split changes: flour = levain mass ÷ (1 + hydration ÷ 100). Final-mix water is not automatically adjusted to hold true hydration constant. In target-dough mode, total flour is recalculated to meet the target.

Does the final-mix list double-count levain flour?

No. The flour blend includes all flour, but the final-mix list subtracts levain flour from the selected flour source. Add the listed final-mix flours and the whole levain; do not add the levain’s flour separately. That one selected flour must cover all levain flour, including seed flour. A starter containing several flours cannot be allocated across separate flour rows in this version.

How does target dough weight handle ingredients entered in grams?

It solves for total flour after accounting for fixed gram amounts and percentage-based ingredients. Gram-entered ingredients stay fixed during ordinary editing; percentage-entered amounts follow the solved flour weight. Only the water part of fixed whole levain is added separately, because its flour is already included in total flour. Impossible formulations show errors instead of a recipe. The target is dough before baking, with no baking-loss allowance.

Do fruit, seeds or other inclusions change the hydration?

Inclusions add to total dough weight, but the calculator does not count them as flour or estimate their water contribution. Their percentages use total flour as the denominator. Moist fruit or other add-ins can affect the actual dough, so the displayed hydration does not account for that moisture.

How do I scale the recipe for several loaves?

Enter the number of loaves and dough weight per loaf in the loaf plan. A valid plan switches to target-dough mode and resizes the current formulation while preserving its ratios. The 0.5×, 1×, 1.5× and 2× buttons also scale the current recipe, including ingredients previously entered in grams. Later scaling does not rewrite the separate loaf-plan fields; use the current summary for the resulting portions.

Does the levain builder change my recipe?

No. It calculates seed, fresh flour and fresh water separately from the recipe. In hydration mode, the optional recipe link takes the recipe’s levain amount and hydration as targets while leaving seed amount under your control. The builder subtracts the seed’s flour and water before calculating additions. Feed-ratio mode is independent; equal fresh flour and water do not guarantee 100% final hydration if the seed has a different hydration.

Does the fermentation planner predict when my dough is ready?

No. It turns your chosen time windows into a planning schedule. The initial 4–8 hour bulk window is an editable project assumption, not a validated fermentation prediction. Temperature and prefermented flour are recorded as context; they do not automatically change the hours. Use dough rise, aeration and strength to judge progress rather than treating the clock as a guarantee.

Sources and reviewed context

References reviewed September 25, 2026. The Perfect Loaf: bulk fermentation guide (opens in a new tab) supports observation-based readiness, not the project’s numerical windows. King Arthur Baking: Dough Temperature (opens in a new tab) supports the four-factor prefermented-dough convention explained above.