Baker’s Math in Action

You’re about to make Vienna bread from The Bread Baker’s Apprentice, when you notice something strange: the pâte fermentée recipe on page 105 nets 16 to 17 ounces; but the Vienna bread recipe only calls for 13 ounces. So, what do you do? Make the full pâte fermentée recipe and throw out the excess? Cut the recipe in half and make do with 8 or so ounces of pâte fermentée?

Neither. You use baker’s math to scale the recipe to 13 ounces. You’ve no doubt noticed the Baker’s Percentage Formula sidebars in Peter Reinhart’s recipes. You may even have read his explanation of the use of baker’s math. But have you ever wondered how to actually go about using baker’s math to scale a recipe?

It’s easier than you think.

Let’s take the pâte fermentée recipe as an example. In baker’s percentages, the recipe is as follows:

  • Bread flour:  100% (remember that the flour will always equal 100%)
  • Salt:  1.9%
  • Instant yeast:  0.55%
  • Water:  65%
  • Total:  167.5% (I know, I know. A total exceeding 100% is maddening; but I didn’t invent baker’s math. I just use it.)

Let’s start with the flour. To figure out how much flour to use, first divide the flour percentage by the total percentage of the recipe:

  • 100/167.5=0.5970

Next, multiply the result by the total amount you want to make, in our case, 13 ounces:

  • 0.5970*13=7.761

The recipe calls for equal amounts of all-purpose and bread flours, so as a final step, divide this amount in half to get 3.88 ounces. (As a final, final step, I rounded this amount to 4 ounces each of all-purpose and bread flours.)

Repeat this process for the remaining ingredients:

  • Salt:  1.9/167.5=0.0113*13=~0.15 ounce
  • Water:  65/167.5=0.3881*13=~5 ounces

And the yeast? To my mind, 0.055 ounce is too small an amount to bother scaling down, so I just used a scant 1/2 teaspoon.

To recap, as long as you know the baker’s percentages, you can scale any recipe to size by dividing the percentage of each ingredient by the total percentage in the recipe, then multiplying by the total amount of dough you want to make.

So, there you have it. Baker’s math in action. Please, try to contain your enthusiasm.