The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Bread math

bobchristenson's picture

Bread math

I'm planning on trying the Norwich sourdough today. The recipe makes a couple large loaves and I want to just make one (half recipe). I'm new to the baker's percentage and figuring in a 100% starter has me unsure of my math. Can I really just halve every weight measure? When I did this I still got the 65% hydration of the original recipe. For future reference, can you confirm this is the right approach?

Add together the flours
Add those to half the sourdough weight (since it's 50% flour)
That gives flour weight

Add water to half the starter weight (again, 50% of starter)
Divide water weight by flour weight to get hydration.

Then as long as the hydration is the same the quantity can be whatever you want. Correct?

Thanks for checking my math! (I failed college algebra 3 times, so I'm a little hesitant of my skillz :)

yy's picture

looks right to me. You're right, you can change all the weight measures in the formula by whatever you want, as long as you change them by the same amount all across the board. So if you want to double the recipe, just multiply everything by 2. If you want a 3/4 recipe, multiply everything by 0.75. If you use the same factor, your percentages won't change.

silkenpaw's picture

... but yes, you can just halve everything, just like yy said. Make sure you halve the starter as well as other amounts. Making sure that the hydration is the same in your halved recipe is a good way to double-check.

Good luck.

flournwater's picture

Your math formula is somewhat complicated.  Make it easier by totalling the weight of all the flour (poolish and dough) then simply combine all the water weight (poolish and dough) and you have the basis for your hydration calculations.



100 grams flour

100 grams water


500 grams flour

325 grams water

Total flour = 600 grams

Total water = 425 grams

Hydration = 71%  (425/600 = .71)

If you want the result to be 65% hydration, simply reduce the amount of water in the dough formula to 290 grams.



ssor's picture

So you then figure the total bread is the water and the flour. That comes to 165 percent of the five pounds. dividing five pounds by 165 equals .49 ounces (about) times 100%  gives you 49 ounces of flour. .49 times 65% gives you 32 ounces about. That will add up to 81 ounces of dough and then you have the weight of the salt. The extra ounce of dough will be lost on the sides of the bowl and on your hands.