Pre-Note: I recommend the use of protective equipment such as latex gloves when undertaking mixing of e-liquids. Furthermore, I recommend the use of a clean and dedicated mixing area to prevent cross contaminations, with adequate spill control and clean up equipment. This is my preference only. This thread is not a total DIY tutorial – you will need to have either a basic knowledge of how to mix bases and flavours, or alternately, be able to follow my other two tutorials found at the following links: Tutorial 1 http://vapercafeaustralia.com/threa...lculate-how-much-nicotine-i-need-to-use.1960/ Tutorial 2 http://vapercafeaustralia.com/threa...ntration-volumes-in-a-recipe.1996/#post-65283 How do I know how to get to my desired VG/PG ratio? I have mixed my flavour components and nicotine, and now I need to calculate my VG/PG additions to get to a 70/30 mix – what about a 50/50 mix, or a 25/75 mix? Well, much the same as working out flavour addition volumes, this again is a matter of calculating percentages. You will note that in the last tutorial, I made a note of what volume of total flavour I had put into my mix. Presumably, in my bottle I now have known volumes of the following: Nicotine base; and, PG based flavourings (for VG based flavourings the method will need to be tweaked a little bit, for alcohol based flavourings, I count them as PG in calculations, as they are usually oils dissolved in alcohol for the purposes of diluting in PG to make the concentrate and therefore alcohol is negligible for the purposes of simple calculations). But how do I know how much extra VG and PG to add to my bottle…. Well, here goes…. The holistic mix calculation will be as follows- Equation 1: Where: PG is Propylene Glycol VG is Vegetable Glycerine CONCENTRATES is your total volume in concentrates; and, NIC is your addition of nicotine base. Lets work on the basis of a 30mL bottle in the first instance, and aim for a 70VG / 30PG mix. And we know that for our total end mix volume, we need 3mL of total PG in the mix to make it 30%. And conversely, we need 21mL of VG to make it 70%. But we already have flavourings and nicotine in our bottle you say! Yes we do, and we know their volumes, and they are all parts of the PG portion of the mix. So, working on from the Raspberry Limeaide recipe in the last tutorial (click here for recipe), and the 24mg nicotine example in the first tutorial we have already got the following in our mixing bottle/beaker: 4.8mL of PG nicotine base. 2.1mL of PG based flavouring concentrates. These together: And we know we have 6.9mL of PG already in the bottle once the flavour concentrates and nicotine have been added. Now, we know that to get to 30% PG in our end mix, we need 9mL, and that we already have 6.9mL in the bottle, so: We need to add another 2.1mL of pure PG to the mix. The last step in this example is easy, as it is simply the addition of a full 21mL of pure VG to the bottle. Presto!!!! A perfect 70VG/30VG mix. Slotted into the equation 1 (above) this is: Broken down: Now, let’s try a different example. We’ll aim for a 50mL bottle, of 50VG/50PG ratio, with 3mg nicotine strength (from 36mg base), and using the Ichigo Keki recipe (click here for recipe)- First, let’s find 50% of our 50mL end volume: Which, in this case, will be the same for both VG and PG, so we know that the total we are aiming for is 25mL of VG, and 25mL of PG in our 50mL mix. Working from tutorials 1 and 2: I have 36mg nicotine base, and want an end product containing 3mg nicotine, therefore using Tutorial number 1 need 4.2mL of PG based nicotine solution. From the recipe, and using Tutorial number 2, I know I need 8.75mL of total PG based flavour concentrates for the recipe. These together: And knowing that we need 25mL of PG for a 50/50 mix: We need to add a further 12.05mL of pure PG to the bottle. Again, the last step is easy as it is simply an addition of 25mL of pure VG to the bottle. All of the above slotted into equation 1 this is: Broken down: Happy Mixing!!!!