This isn't correct my friend, you don't know the differences in the density of the different powders. one gram of one thing can weigh considerably different and take up a much different volume than one gram of another thing.
here is a link for you to do it RIGHT.
http://www.elitefitness.com/forum/showpost.php?p=6188236&postcount=17
cut and paste for you:
yes, if i undestand your question right....if you scales are only accurate to .01g as most cheaper ones are you would be best to fill up 50 capsules with filler powder, then dump it all out on the scales cap by cap....this is the weight of the filler powder that will fill up all the capsules.....divide that by 50 or however many are in the control group....that will be the weight each capsule contains of filler powder
now you would need to do the same with the powder you want to cap....find out how much one capsule will hold of it doing the same thing. here is where scales to the .001g or mg work best, you don't have to use so many in your control group.
now you have to figure out a ratio of difference for the amount of volume the filler powder contains per weight versus the powder you are capping....for example anavar weighs much more per cap than say winny will.
say your filler powder is .250g per capsule, and your powder is .350g per capsule, and you have 50 capsules and you are making 50mg/capsule
now 50X.250 is 12.50 grams total powder, but you are going to add .050 of another substance....
.050X50 = 2.5g
you would normally think 12.5-2.5 to get how much filler, but the volume of filler is .250g/capsule and the volume of powder is .350g/capsule, so the powder in question is denser than the filler so that has to be taken into account
i do it like this
.250/.350 is .71 so the filler powder is only 71% of the same comparable volume of the powder you are making. or a 29% difference, or 1-.71 or 29, use this number in the following
so now do 12.5g - [2.5 + (2.5 X (1-.71))] = 12.5-3.225 = 9.275g filler powder
now add 2.5g powder to that 9.275 and mix like hell, this will then fill all the capsules evenly