Question: how many ounces are in a cup of sourdough starter?
Answer: To reduce the amount of stiff sourdough starter from 30 percent to 20 percent: Reduce the starter to a rounded 1/3 cup (3.5 ounces/100 grams). To the rest of the dough, add 1 full tablespoon (about 1 ounce/16.6 grams) water and 3 1/2 tablespoons (1 full ounce/33.3 grams) flour.