December 20, 2012 - 2:37am

## starter hydration maths question.

i have worked through all the maths lessons and i still seem to have a problem

where the maths of starters / sponges / poolish / biga are concerned.

here is what i mean.

i take 10g of starter @60%

so how much is flour and how much is water?

i add 20g water and 20g flour.

total weight is now 50g.

what it the hydration now?

i add a further 6g of water and 24g of flour.

total weight is now 80g.

what it the hydration now?

what i need to see is how much water and flour is totaled up for each calculation.

First I would question whether it's really necessary to build your starter in this way. Seems bizarre / random to me with no real reasoning unless you can explain otherwise.

In the case of just flour and water where hydration is known, calculate like this... For example a dough @ 60% hydration you have a total of 160% (added 100% represents flour). 160% in decimal = 1.6. So 10g dived by 1.6 = 6.25. So of the 10g 6.25 is flour and the remaining 3.75 is water.

i was given the build plan and i have been using it for a while successfully.

i just wanted to check the maths.

from what you said i have come up with this.

do you think the maths now works out right and the hydration levels are correct?

yes this is correct.

the hydration % of your dough at any time is:

( TW / TF ) * 100

where TW is the total amount of water in your dough, and TF is the total amount of flour in your dough.

thanks.

i plan to give your Sourdough recipe for beginners a try.

John

Happy to help. Let me know how it turns out!