Baker’s Percentages

Mar 2020, updated May 2020

Serious bakers use weights in their recipes, because scooping technique and humidity introduce a lot of variance in volume-based measurements. To make it easy to scale recipes up and down, bakers often express weights as percentages of the flour weight. This is completely different from normal math, where we’d use percentages of the total weight.

There are two approaches to percentage-based sourdough baking: one breaks the starter into flour and water weights, and the other treats it as a separate ingredient (ignoring the flour content). As an example, consider a mix of 100g flour, 100g water, 10g salt, and 10g starter (itself an even mix of flour and water, aka 100% hydration). Using the first approach, we’d calculate percentages like this:

Ingredient Weight Baker’s Percentage Normal Percentage
Flour 100g dry + 5g in starter 100 47.7
Water 100g + 5g in starter 100 47.7
Salt 10g 9.5 4.6

Using the second approach, we’d have this:

Ingredient Weight Baker’s Percentage Normal Percentage
Flour 100g 100 45
Water 100g 100 45
Salt 10g 10 5
Starter 10g 10 5

The Tartine bread book uses the second approach. Chad Robertson says that it’s more common in commercial bakeries: because the same starter is used in all the recipes, it’s easier to treat it as an ingredient rather than a mix of flour and water. I do the same.