# Changing premix ratios



## RichJB (18/12/16)

Hi all

Following a question from @kev mac which I answered regarding premixes, some folks have expressed interest in how to tackle this common problem of how to change your premixes. You bought 50VG/50PG premix from a vendor but now you want to mix at 70VG/30PG or whatever, how on earth do you know how much to add? It's actually a very easy thing to calculate. All you need is a calculator. And by that I mean your Windows or desk calculator, not even a juice calculator.

Any time you want to change the ratio of a premix, you must of necessity increase one ingredient (VG or PG) while reducing the other. The key to calculating how to change your premix is to *only focus on the ingredient you want to reduce. *If you want to change a 70VG/30PG premix to a 50VG/50PG premix, you are reducing the ratio of VG in the premix. So VG is the only thing you would focus on. If you want to change a 50VG/50PG premix to 60VG/40PG, you would focus on PG as that is the ingredient you want to reduce. So here is the step by step methodology.

1) Identify which ingredient you want to reduce - PG or VG

2) Identify how much of that ingredient is in 100ml of your existing premix. This number is X. So if you are working with a 60VG/40PG premix and PG is what you want to reduce, then X=40.

3) Identify how much of that same ingredient you want in 100ml of your desired premix. This number is Y. If you are reducing PG and you want to make an 80VG/20PG premix, then Y=20.

4) Divide Y by X.

5) Multiply the answer by 100.

6) That is the percentage of your existing premix that you must use in your new premix. The remaining percentage of the new premix will be the ingredient that you wish to increase.

Practical example: I have a 62VG/38PG premix. I want to change that into an 83VG/17PG premix. So step by step:

1) What ingredient do we want to reduce? Our new premix is higher in VG so we want to reduce PG. So all our calculations are concerned only with PG.

2) How much PG is in 100ml of our existing 62VG/38PG premix? Easy: 38ml. So X=38.

3) How much PG do we want in 100ml of our new 83VG/17PG premix? Equally easy: 17ml. So Y=17.

4) Divide Y (17) by X (38) which = 0.447

5) Multiply by 100 which = 44.7. This is the percentage of our existing premix that we put into our new premix. We then top up with the ingredient we want to increase, which is VG.

6) To make our new premix, we add 44.7% existing 62VG/38PG premix to 55.3% VG. That will give us our new 83VG/17PG premix.

To test the calculation:

Our existing premix contains 38ml of PG per 100ml
But we are only using it at 44.7% concentration.
44.7% of 38ml = 16.986ml
That is as near to 17ml as makes no difference. 

Hope this makes sense.

Reactions: Winner 5 | Useful 1


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## RichJB (18/12/16)

If you don't want to do the arithmetic and just want some shortcut answers to how to change your premix, here are some common examples:

To turn 50/50 into 70VG/30PG: 60% base + 40% VG.
So if you want to make, say, 230ml of it, then 60% of 230 = 138ml base plus 40% of 230 = 92ml VG

To turn 50/50 into 60VG/40PG: 80% base + 20% VG

To turn 50/50 into 80VG/20PG: 40% base + 60% VG

To turn 70VG/30PG base into 50/50: 71% base + 29% PG (not exact but near as darnit)

To turn 70VG/30PG base into 60VG/40PG: 86% base + 14% PG (not exact but near as darnit)

To turn 70VG/30PG base into 80VG/20PG: 67% base + 33% VG (not exact but near as darnit)

Reactions: Winner 3 | Useful 1


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## kev mac (20/12/16)

RichJB said:


> Hi all
> 
> Following a question from @kev mac which I answered regarding premixes, some folks have expressed interest in how to tackle this common problem of how to change your premixes. You bought 50VG/50PG premix from a vendor but now you want to mix at 70VG/30PG or whatever, how on earth do you know how much to add? It's actually a very easy thing to calculate. All you need is a calculator. And by that I mean your Windows or desk calculator, not even a juice calculator.
> 
> ...


Unlike me I bet you paid attention in math class, thanks @RichJB ,

Reactions: Like 1


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## Silver (20/12/16)

Thanks for making this thread @RichJB 
Very useful

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## Tockit (20/12/16)

Jeeeez, i cant math this early in the morning  LOL

Reactions: Funny 1


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## KZOR (20/12/16)

RichJB said:


> So here is the step by step methodology.



To avoid steps 1 to 50 and a revision course on Maths 101 make 5ml batches. If ratios are wrong ..... bin .... repeat .... smile. 

Thanks for the great post @RichJB. Very helpful and informative.

Reactions: Funny 2


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## shaunnadan (20/12/16)



Reactions: Like 1 | Funny 1


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