Bread Hydration + Windowpane Predictor — Baker's Percentage Calculator with Flour-Protein Ceiling

Why baker's percentages beat recipe arithmetic

Quick answer: baker's percentages express every ingredient as a percentage of total flour weight (always 100%). Salt 2% means 2g salt per 100g flour. This makes scaling, substitution, and comparison across recipes trivial — and exposes recipes that secretly violate the chemistry-determined ratios that actually work.

A recipe that says "3 cups flour, 1.5 cups water, 1.5 tsp salt" is opaque. The same recipe in baker's percentages — "100% flour, 64% water, 1.7% salt" — instantly tells you it is a standard lean dough at typical hydration with under-salted ratios that will taste flat. Once your eye trains to baker's %, you spot drift the moment you open a recipe.

The flour-protein-extensibility ceiling

Quick answer: gluten is a protein network that holds water through hydrogen bonding and physical entanglement. The maximum sustained hydration before the network collapses scales roughly with protein content — empirically ~4.5% × protein% + 25%. Bread flour 13% protein → ~83% ceiling. Cake flour 8% → ~61% ceiling. Pushing past the ceiling produces sticky paste, not extensible dough.

The ceiling is empirical, not absolute — experienced bakers using slap-and-fold technique can push 5-10% beyond. But for the home baker following a recipe, the ceiling is the difference between bread that holds structure during proof and a wet mass that spreads flat in the oven.

Windowpane test prediction — flour-protein × hydration × method

Quick answer: the windowpane test stretches a piece of dough thin enough to see light through without tearing. Time-to-windowpane scales approximately as: base 10 min × protein-factor × hydration-factor × method-factor. Bread flour at 65% hydration with hand kneading reaches windowpane in 8-15 min. Cake flour at the same hydration may never reach windowpane (insufficient protein). Stand mixer cuts time roughly in half. Slap-and-fold for high-hydration cuts time by ~30%.

Common scaling mistakes baker's percentages prevent

• Salt drift — recipes vary salt 0.8% to 2.5% with no explanation. Below 1.5% bread tastes flat; above 2.5% yeast slows and bake time extends. The wizard flags both.
• Yeast over-correction — doubling a recipe and doubling yeast over-proofs the larger batch (more dough mass = more retained heat = faster fermentation). Use 75-85% of scaled yeast at 2-3x.
• Whole-wheat hydration miss — whole-wheat absorbs ~5% more water than white through bran. A recipe converted from white to whole-wheat without adjusting hydration produces dry, crumbly bread.
• "Add more flour if too sticky" — the most common ruin. High hydration is supposed to be sticky during initial mix. Adding flour reduces gluten-water ratio and creates dense, dry crumb. The wizard's hydration-feedback distinguishes "high but workable" from "actually overhydrated."

Variables this model does not capture

The protein-ceiling formula is empirical, derived from McGee's discussion of gluten extensibility and Modernist Cuisine's hydration-vs-extensibility curves. Real-world variables — flour age, ambient humidity, water mineral content, exact protein composition — shift the ceiling 5-10% in either direction. Use the prediction as a starting point. The wizard's job is to flag when you are about to violate the protein-determined physics, not to substitute for the dough's actual feel in your hands.

For very long ferment recipes (sourdough 24-48hr), enzymatic activity (proteolysis) actually weakens the gluten over time, lowering the effective ceiling. The wizard does not model long-ferment proteolysis — adjust manually for very long ferments by reducing hydration 3-5%.

Sources and further reading

This wizard's predictions draw from the canonical bread-chemistry literature: Harold McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed. (Scribner, 2004), Ch. 10 on dough chemistry and gluten development. Modernist Cuisine, Nathan Myhrvold et al. (2011), Vol. 3 on bread-volume hydration-vs-extensibility curves and crumb-structure analysis. Peter Reinhart, The Bread Baker's Apprentice (Ten Speed Press, 2001), for baker's percentage normalization and dough-formula notation. For sourdough specifically, Chad Robertson, Tartine Bread (Chronicle Books, 2010), on long-ferment hydration management and slap-and-fold technique.