Thanks for this question. I have never tried quinoa. I shall now try it.
I found this information on the internet. I hope you find it helpful.
Half a cup of dry quinoa will give you about 2 cups of cooked quinoa, and since it's (kind of) a whole grain, it's fairly filling even though it's the size of couscous when it's done.
Therefore a quarter of a cup will make 1 cup when cooked.
If you cook a quarter cup of quinoa in half a cup of water, you'll end up with three-quarters of a cup.