How much water does pasta absorb when it is cooked?
You need 1.1x as much water as pasta for al dente! I measured this myself, cooking penne rigate (in water, not sauce) - 200g of pasta weighed 420g after being cooked and thoroughly drained.

The estimate below from the nutrition facts is 1.4x, which probably corresponds to typical American overcooked pasta - a surprisingly large difference from mine. I'm guessing you'll be somewhere between, maybe 1.25x.



You can also ballpark it from nutrition facts. Cooked spaghetti has 31g carbs per 100g pasta, and dry spaghetti has 75g carbs per 100g pasta. So 100g dry pasta turns into 100g*75/31 = 242g of cooked pasta, meaning the added water was ~1.4x the weight of the pasta. So for a pound of pasta, that's 1.4 pounds or about 2&nbsp;2/3 cups of water. Given people's tastes, this might be a little past al dente, so I would personally start with maybe 1.25 cups of water then add a little more if necessary. (I'll also try cooking pasta normally and weighing it if I get a chance.)

Note: if you have a significantly different variety of pasta, it will obviously behave differently. This is for pasta that's 13% protein and 75% carbohydrates. For the standard 2oz/56g (dry) serving on the package, it'll say 7g protein and 41-42g carbohydrates. I checked Barilla, De Cecco, Ronzonni, Garofalo, Safeway store brand, Trader Joe's store brand, and those nutrition facts, and they all matched. If you're branching out to other styles like whole grains or egg noodles, things will obviously change, but things are very uniform in the US.