So does that mean it's 6 of 1 and half dozen of the other with metric units? And doesn't the weight per volume affect your #'s? because it seems like 1ml of pg is going to weigh less than 1ml of vg.
The people who use weight do the conversions which are quite easy, and the calculator makes it all really easy. Rather than explain it all again, I refer you to the website I posted earlier:
eJuice Me Up - Best eJuice Calculator
While I don't use weight 99% of the time, I do own a scale and have used it. Since most recipes I post and see are in PERCENTAGES, weight is not much more complicated than volume. As mentioned, it really does seem to come down to just how accurate one wants to be. Generally, weight will be more accurate, but when working with liquids, particularly heavy, viscous liquids, we don't get the all the material into the containers anyway, so I find volume easier, and also use syringes, and do not worry whatsoever about the miniscule amounts left in beakers, syringes, etc. Close works great for DIY, and I recommend it, though some prefer the weightier methods. To each their own.
I'm must more interested in getting done and saving time, and making it easy and quick, than practically anything else. Once you get a feel for mixing, you can be off quite a bit and still make delicious juices, as long as you generally keep mixing ratios in line by mixing consistently. All I'm going to say....recommend the website posted for further information. Happy Vaping!