Calculate the water amount needed for making sourdough usually for bread - based on starter amount, flour amount and desired hydration percentage of sourdough.
Assuming that starter is made of 100% hydration (same amount of water and flour).
Total amount of starter in grams - usually a combination of water and flour
The total amount of flour you want to use in grams
Desired percentage of sourdough hydration
The amount of water in grams that needs to be added to achieve the desired percentage of hydration of the sourdough.