I notice when I double a recipe, the dough doesn't add up exactly twice as much. Is there a way to figure out how to do it without losing the total volume?
I'm not quite sure what you're meaning here. Are you measuring by volume (cups) or by weight? if you're doubling something by doubling the weight of each ingredient it should exactly double in weight. When doubling measurement by volume you're also doubling every tiny little inconsistency in measurement. Over, say, the course of 8 cups of flour for a double recipe the slight differences in how compacted the flour in each 1-cup measurement would then add up.
Yes, I measure the flour in cups instead of weight. I normally use a no-brainer recipe that calls for 5 cups of flour and 2 cups of starter to make 2 medium loaves. But as I doubled it: 10 cups of flour and 4 cups of starter, it turned out to less than 4 equal loaves. That's very true that a small inconsistency in each cup will make a significant difference in 10 cups. Maybe I should use weight next time when I double the same recipe. Thanks!