What is Baker's Percentage?

Most bakers learn ratios by weight, not by cups or grams alone. When you write a sourdough formula as baker's percentages, you're writing a formula that works at any scale. A 500g flour loaf and a 25kg production batch use the exact same ratio of water, salt, and starter—just different absolute weights. This matters because scaling by volume or by doubling cup measurements introduces errors that compound: a doubled batch doesn't bake the same as the original. Let's use a real example: a chocolate layer cake. You have a recipe that calls for 400g all-purpose flour, 300g sugar, 180g butter, 150g eggs, 100g cocoa powder, 8g baking soda, 4g salt, and 200g whole milk. Right now, you're baking this in batches of 2 cakes. Next month, a hotel wants 12 cakes for a corporate event. Do you multiply every ingredient by 6? You could—but baker's percentages let you verify the formula is sound before you scale it, and they make it impossible to accidentally leave out an ingredient when you're scaling up. Baker's percentage also exposes recipes that don't make sense. If your chocolate cake recipe uses 75% sugar by weight of flour, that's a rich, moist cake—and if a supplier changes cocoa powder brands, you can recalculate the exact impact on your ingredient cost per cake. A cocoa powder that's $8/kg instead of $6/kg adds exactly $0.48 to the ingredient cost of a 400g flour batch (because cocoa is 25% of flour weight in your formula). You know this before you quote the next order. Baker's percentage is standard in bread baking, where hydration ratio (water as a percentage of flour) determines everything from crumb structure to fermentation speed. A 65% hydration dough behaves differently than a 72% hydration dough—and that percentage stays constant whether you're mixing 1kg or 100kg of flour. The same logic applies to cake, pastry, and cookie formulas: the percentages tell you what kind of product you're making, and the absolute weights tell you how much to buy.