Methodology

The calculator ratios, schedule timings, starter multipliers, and troubleshooting thresholds on this site are cross-referenced against King Arthur Baking, The Perfect Loaf, ThermoWorks, Bob's Red Mill, and 10+ published baking sources. Where our values differ from the literature we document why; where a number is a site-specific rule-of-thumb we label it as such. Last reviewed April 2026.

How we built these tools

Every calculator range, schedule window, and troubleshooting threshold on this site maps to a specific line in our open data files — and every one of those lines was audited against published sources before this page was written. The goal is not to invent new formulas, but to apply well-established baking math and fermentation science to a tool that's faster than flipping through a book.

Baker's percentage math

Every recipe the calculator produces uses standard baker's percentages, where flour is 100% and every other ingredient is expressed as a percentage of flour weight. This is the notation used by Hamelman's Bread, Forkish's Flour Water Salt Yeast, and every professional bakery. Our default fixed values — 20% starter, 2% salt — sit squarely in the middle of published ranges (King Arthur publishes 1.8–2.2% salt; 15–25% starter is typical for a levain build).

When you enter flour, hydration, and starter hydration, we compute total water and salt so that the final dough hydration — including the water already in your starter — matches what you asked for. The math is in shared/composables/useBakerMath.ts.

• King Arthur Baking — Baker's Percentage reference
• The Perfect Loaf — Baker's Math and Percentages

Hydration bands (65%, 70%, 75%, 80%, 85%)

Our beginner-to-expert labelling (65% low, 70% medium, 75% high, 80–85% very high) follows the consensus view on home-baker progression. King Arthur's sourdough starter guide recommends beginners stay at 65–70% until they're comfortable with shaping; The Perfect Loaf's Flour for Sourdough guide treats 80%+ as territory requiring 12%+ protein flour — both specs we enforce in our calculator notes.

• The Perfect Loaf — Dough Hydration guide
• King Arthur Baking — Beginner's Guide to Sourdough

Schedule timing (warm, moderate, cold)

The three-band temperature model — warm (75–80°F), moderate (68–72°F), cold (60–65°F) — is a site convention derived from The Perfect Loaf's continuous temperature-to-time chart, simplified for planning use. Our bulk fermentation windows match published values when the label refers to dough temperature (ambient plus mixing friction, usually +3–5°F), which is the professional convention.

Starter feeding ratios — 1:1:1 through 1:10:10, with peak times of 4–6 hours through 12–16 hours at 68°F — come directly from Summit Sourdough's published ratio table and match King Arthur's 2025 feeding-ratio trial and Brod & Taylor's guidance.

• The Perfect Loaf — The Importance of Dough Temperature
• Summit Sourdough — Starter Feeding Ratios
• Brod & Taylor — Feeding Ratios

Starter temperature multipliers

Our eight-point multiplier curve (1.6× at 60°F down to 0.45× at 85°F, with 68°F as the 1.0 baseline) fits a Q₁₀ ≈ 2.55 Arrhenius model — squarely within the Q₁₀ = 2–3 consensus for lactic-acid-bacteria and yeast fermentation at these temperatures. The warm end (72–85°F) tracks pure Q₁₀ = 2.5 within 2%. The cool end (60–65°F) runs 8–10% slower than pure Arrhenius, which accounts for the cold-induced lag in LAB activity that the Q₁₀ model alone doesn't capture.

• ThermoWorks — Sourdough Times and Temperatures
• Bloom Cooking — Fermentation Temperature & Timing Guide
• The Fresh Loaf — Debra Wink on Lactic-Acid Fermentation

Flour specifications

Protein percentages for bread flour (11.5–13.5%) and all-purpose (10–12%) match King Arthur's published specs — we explicitly cite their 12.7% bread-flour and 11.7% all-purpose numbers on our flour pages. Whole-wheat, spelt, and semolina protein ranges are verified against Bob's Red Mill. Dark-rye protein was originally listed as 14–16% on this site; we corrected it to 12–14% after cross-referencing Stanley Ginsberg's Rye Baker classification. Oat flour protein was similarly corrected from 12–14% to 15–17% based on whole-grain oat analyses. Semolina's blend cap was raised from 50% to 100% to reflect that Pane di Altamura is traditionally made from 100% durum semolina.

Nutrition figures (calories, fiber, iron) per 100g come from USDA FoodData Central entries, with each flour's FDC ID linked on its page.

• King Arthur — Protein Percentage in Flour
• The Rye Baker (Stanley Ginsberg) — Rye Flour Classification
• USDA FoodData Central

Troubleshooting thresholds

The internal-doneness range of 205–210°F is directly sourced from King Arthur Baking and ThermoWorks — both publish it as the standard for lean doughs. Scoring depth (1/4 to 1/2 inch) matches King Arthur's guidance. Dutch-oven preheat was originally listed as 45–60 minutes on this site; we widened it to 30–60 minutes after confirming King Arthur treats 30 minutes as their minimum. Scoring angle was originally 15–30° from horizontal; we corrected it to 30–45° from the dough surface after cross-referencing The Perfect Loaf's ear-formation guide.

• King Arthur — How to Tell When Bread is Done
• ThermoWorks — Bread Temperature Guide
• The Perfect Loaf — How to Score Sourdough Bread

Site conventions and empirical rules of thumb

Some values on this site are rules of thumb — consistent with the direction of the baking literature but without a single authoritative numeric citation. We label them honestly here so you know where the confident citations end and practical simplification begins.

• Flour fermentation-speed multipliers (whole wheat 0.75×, rye 0.6×, spelt 0.8× relative to white). Direction is supported by enzyme-activity literature — whole-grain and rye flours ferment faster due to mineral and pentosan content — but the exact multipliers are site-calibrated, not lifted from a published paper.
• Altitude hydration adjustment (+2–5%), high-hydration protein floor (12%), whole-grain beginner cap (30%), and over-fermentation timeout (>24 hours): these are consensus home-baker heuristics rather than specific citations. They agree with advice from King Arthur, The Perfect Loaf, and Breadtopia but are not tied to a single published value.
• Warm/moderate/cold schedule bands are a site convention. The Perfect Loaf publishes a continuous temperature-to-time chart; we discretise it into three bands for planning purposes. Where the bands shade into each other, the continuous model is more accurate.

What you can't get from books

Some of the best sourdough references — Hamelman's Bread, Forkish's Flour Water Salt Yeast, Robertson's Tartine Bread, and the Modernist Bread volumes — are not available online in full. Where our numbers match values from these books, we cite them via widely-quoted excerpts on reputable blogs (King Arthur, The Perfect Loaf, Breadtopia) rather than inventing page numbers. If you own the primary sources, we encourage you to verify directly.

How to report a discrepancy

If a number on this site disagrees with a source you trust, we want to hear about it. Email us at [email protected] with the page URL, the site value, your source, and its citation. We update this methodology quarterly and credit corrections.

This methodology page was last reviewed and cross-referenced on 15 April 2026. The full reconciliation worksheet — including every numeric claim, its source file, the cited authority, and the verdict — lives in planning/methodology-audit.md in the site's repository.