Why not just learn how to cap? I would really like to see you weigh out 20mg of powder every time you need a dose. That would be a joke.
First you figure out how much powder one empty cap holds. Size 3 caps hold approximately 200mg of powder. If you are making 100 20mg Anavar for example you would need 2 grams of Anavar powder, and 18 grams of "filler". You mix the 2g of Var powder with the filler in a bag, and then pour the mixture onto your capping plate filled with empty capsules. Scrape the powder into the empty capsules, pack the powder down into them, and scrape again until you have all the powder packed into the capsules. Drop the plate, and put the tops on them.
The math all depends on the size of your empties. I like size 3 caps because they leave you much less room for error.