Bread Dough Formula Math Dilemma (Some Help, I Hope)
From time to time I read posts with questions like this:
"I want to use 435 grams of starter at 70% hydration in a bread dough formula that calls for 500 grams of flour at 60% hydration. How do I figure out how much flour and water I need to add in order to meet that requirement?"
Here's a primer that should alleviate the headache you might normally experience trying to figure it out.
435 grams starter at 70% hydration means you'll divide 435 by 1.70 for a total of 256. That means 256 grams of your starter is flour. Now subtract the known flour weight from the total starter weight and you'll get 179 grams of water. So your 70% hydrated starter is the product of 256 grams of flour and 179 grams of water.
The bread formula you're working with calls for 500 grams of flour with a 60% hydration level. So all you have to do is make up the difference between the 256 grams of flour in your starter and the 500 total you need for the bread (500 minus 265 equals 244) and add that much new flour to the mix. 60% hydration for 500 grams of flour requires 300 grams of water. You already have 179 grams of water in your starter, so all you need to do is add another 121 grams of water and you've achieved your goal.
Total Starter Weight/Hydration Percentage (as a decimal) = weight of flour content
Total Starter Weight minus Flour content weight = weight of water in the starter
The principal applies, regardless of the hydration level of the starter. Of course, for an 80% hydrated starter, you'd need to change the hydration percentage figure from 1.70 to 1.80 to identify the comparative weight ration of flour to water in your starter.