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How to calculate nicotine (nic) concentration for DIY with very basic math

Discussion in 'DIY E-Liquid' started by mrcoolbp, Sep 11, 2013.

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  1. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    This post is for people who are comfortable with very basic math and maybe word problems. No trig, calc, or algebra required. This is also for those who don't like using ejuice calculators or find limitations therein.

    When I first started DIY I asked a chemist friend for some magic formula to help me calculate concentrations. His response was: "oh that's easy, it's just additive," but it took me a few days to understand what he meant. In chemistry we need to add multiple solutions with different concentrations, formulas are helpful. The great thing about DIY is there is only one solution (nicotine base), we are just diluting that.

    So what the heck am I talking about? I wanted a formula that I could just plug numbers into. If you want that, great, just use a ejuice calculator. I have never used one. I figured this out using logic and a touch of math. If you understand a tiny bit about percentage/decimal/fraction math, you don't need a calculator. It's much easier and quicker for me to do with a regular calculator and paper. Maybe that's just me. If not, then read on.

    [HR][/HR]

    Some key points for this method are:
    • I mix my PG/VG at a ratio I like prior to mixing a juice. So all I have is Nic base, PG/VG base, and flavor.
    • I use mostly super-concentrated flavors and they require only a few percent in the mix which allows you to basically forget this part of the percentage
    • If you use a higher percentage of flavor, you can just incorporate the flavor into the PG/VG amount using very basic percentage math which I'll cover

    I'll use obvious examples so that it is easier to understand mentally, but you can easily do this for any batch after very little practice.

    Here's an example:

    You have 100 mg/ml nic base, and you want 25mg/ml juice, let's say 10ml of it. This is wicked easy: 2.5ml of 100mg juice and 7.5 ml of 0 mg PG/VG.

    2.5 ml of 100mg/ml (2.5 * 100) is 250mg of nicotine. 100 mg/ml is 100mg/1ml, so it looks like this in long form:

    2.5ml__100mg
    -------- * ------------- = 250 mg
    1_______1ml

    (Notice the "ml" is crossed out, this happens when we "cross multiply" using fractions.)

    Because the 250mg is spread out through the whole batch we divide 250 mg of nicotine by the total finished volume (250mg/10ml) and you get 25mg/ml.

    How do I know this? The key is understand your units. The unit mg/ml means "milligrams per milliliter" or "milligrams divided by milliliters". I know some of you are saying, "duh!" and some might be saying: "well that was an easy one...." Some of you might be confused.

    If the ratios are not immediately obvious, just guess, check your math, and guess again if you're wrong.

    [HR][/HR]

    Another example:

    We have 36mg/ml nic base, and we want 12mg/ml juice. I think I'll make 30 ml this time. I notice 36 is "3 times 12". So I know I'll need 1 part nic base and 2 parts PG/VG base. That gives us 10 ml of 36 mg/ml base and to add 20 ml of PG/VG base to dilute that to 12mg/ml.

    Math check:

    36mg/ml * 10 ml is 360mg total nicotine. 360mg total / 30ml total volume is 12 mg/ml concentration (360mg divided by 30 ml)

    This should be relatively simple to grasp if you are comfortable using a little bit of math.

    [HR][/HR]
    For higher flavoring percentage (over 5% maybe):

    Okay, so you use Flavor west and need 25% flavor. How do we account for that in the above example? Super easy. We were using 2 components before (nic and PG/VG). Now we need a 3rd. But we already know the correct percentages, we just need to replace some PG/VG base with some flavor. Once you find out how much nic base you need for your batch (10 ml nic base in a 30ml batch in this case) we know the 20ml remaining will consist of PG/VG and flavor. So if we need 25% of the total batch in flavor, multiply 25% by 30 ml. 25% is .25 in decimal form, so the math looks like this:

    .25 * 30ml = 7.5ml flavor

    Subtract that from our 20ml figure from before and you get 7.5ml flavor and 12.5ml PG/VG base. (math check: 7.5ml + 12.5ml = 20ml YAY!!)

    [HR][/HR]

    In order to use this method you need to visualize the approximate amounts in your head a little (draw a diagram if it helps), and you need to feel a little comfortable using basic math. I encourage you to use units everywhere possible.

    I keep track of recipes in ml and percent where possible so I can just multiply later for different sized batches. This can be done on paper or in digital form.

    Does this make any sense to anyone? I'm happy to clarify.
     
  2. MsComptrtchr

    MsComptrtchr Ultra Member Verified Member ECF Veteran

    And you choose this method over an eliquid calculator because??

    E-Juice / E-Liquid Calculator (You have to go to the Ahlusion site and certify that you are 18 to view this link.)
     
  3. ukeman

    ukeman PV Masher Verified Member ECF Veteran

    Supporting member
    Aug 22, 2010
    Kauai, Hawaii
    Very nice, and doable, but its 7:42 pm after working today. I'm a glazed donut hole. and a DIY newb actually.

    Lol... sorry, and I am glad that like you I use concentrates; and mostly VG (at 6mg/ml). Most of my recipes are 3-4% total flavoring.

    I opt for the calculators... i like the one that can give you up to 10 different flavors (although i have only used up to 3 so far).

    And thank God I don't even have to save my recipes, since everything is kept basic: 3-4% flavor in a 6mg VG (with some PG ok)... how's that?
     
  4. LucentShadow

    LucentShadow Super Member ECF Veteran

    Dec 28, 2011
    Michigan, USA
    Nicely presented, mrcoolbp.

    I, too, prefer to just do the math myself. I find it convenient to just keep a pocket calculator in my mixing area for calculations that are not easy to do mentally.

    I've seen posts in the past from new mixers using e-liquid calculators incorrectly, and coming up with dangerous results. Hopefully this does not happen often, but knowing how to manually check their results is always a good idea.
     
  5. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    Because I prefer to understand things on every level possible. I might be a rare breed these days, most people don't care what happens under the hood. Also, it's easier for me to work with pen and paper while mixing (don't want e juice all over my ipad/computer). Plus it's only one or two basic math problems, the rest is figuring out where to put your numbers. That's the "word problem" part, I guess I've always been good at those. It looks like a lot of info because I wanted to spell it out as clearly as possible.

    When you do it this way, it's easier to perform off the cuff modifications as well because I know what's what. This understanding helps me convert between drops and percentages too. I've also seen people improperly use e juice calculators, that really worries me when working with poisonous chemicals. This is why understanding is important.

    Having a cheap pocket calculator at my DIY station makes this a snap (literally it takes me less then 30 seconds)

    I can see why this might be a little more difficult for a recipe with 10 flavors, separate PG and VG, nic base, additives etc. but I haven't had the need for that yet, and it could still be done. Who knows, If I ever have 15 components for a recipe, I might just bust out an e-juice calc...
     
  6. ukeman

    ukeman PV Masher Verified Member ECF Veteran

    Supporting member
    Aug 22, 2010
    Kauai, Hawaii
    hats off. that kind of knowledge and ability is admirable.
    it made me think of my daughter in high school, and my wish for her to be self reliant.
    not to mention the zombie apocalypse...jk. seriously though, them that know "how" to fish and all.
     
  7. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    Yeah, it's probably all for not. E-Juice calculators make all this obsolete, but that is how they made them in the first place. At least it's here for somebody to search and find if they want too.

    Thanks for the kind words guys. Vape on!
     
  8. ukeman

    ukeman PV Masher Verified Member ECF Veteran

    Supporting member
    Aug 22, 2010
    Kauai, Hawaii
    Its a great excercise for the mind... so many of us take it for granted, but believe me, at 63yrs, and a full life, the brain needs excercise!
    I'm living proof of how things can go south...

    There's something very logical about your steps and this process like business math or "algebra for life" heheh... maybe i'll take my own advice.
    I have to admit, after a few years of vaping, i've gotten spoiled and my compulsivity has not diminished. That "instant gratification" vice is running rampant.

    thanks for the formula.
     
  9. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    It's my pleasure, sorry it wasn't more concisely written...
     
  10. InTheClouds

    InTheClouds Super Member Verified Member ECF Veteran

    Jun 18, 2013
    Murphy, NC, USA
    Whew... I feel better now! I thought I was a dying breed. I too prefer to do the math myself just to keep my brain active. Once in a while if I doubt myself I will double check my math with the e-juice calculator, but so far I have managed to do it right. I mix up a 236ml bottle of 6% then just add my flavors for myself in 30ml bottles, but my sister uses 18% and likes stronger flavors so I do the math when I make hers.
     
  11. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    18% would be 180mg/ml which would likely win you a trip to the hospital. I'm guessing you meant 18mg/ml. Careful with the units people.
     
  12. rebgold

    rebgold Super Member Verified Member ECF Veteran

    Jan 27, 2013
    Wichita, KS
    I'm working on figuring out a similar formula myself. I have 50/50 pg/vg 48 mg nic. I have a bottle of pg. I want to make 120 ml bottle of unflavored base to have handy so I can just throw flavorings into little 15 ml bottles when I want to make something new.
    I prefer 70 to 80% PG so I didn't order any straight VG figuring the mix of the nic base would cover the VG.
    If it was a 50/50 mix I'd get 12 mg, and my brain only does kitchen math, so I'm thinking 2/3 nic base 1/3 PG would get me about 18 mg? That way I could measure in ounces or even cups with my kitchen beaker.
    The only factor I'm iffy about is whether or not I want to use any distilled water and how much I would use if I did.
     
  13. zoiDman

    zoiDman My -0^10 = Nothing at All* ECF Veteran

    Supporting member
    Apr 16, 2010
    So-Cal
    I to am someone who Likes to see what's Under the Hood. And like Turning the Wrench with a Little Algebra.

    I can't link to this thread because it is Closed. But you might Like reading it.

    http://www.e-cigarette-forum.com/forum/general-e-liquid-discussion/257260-adding-50mg-ml-nicotine-juices-already-containing-nic.html
     
  14. Road_House

    Road_House Senior Member ECF Veteran

    May 12, 2013
    SE PA
    You will need your finished nic base to be 38% of total volume to get to 18 mg/ml. Since you are starting with a 50/50 mix, only 19% of that will be pg. Add say 10% flavor and your total pg will only be 29%, well short of your 70-80% goal so you will need to add another 40-50% plain pg to your recipes.

    The easiest way to figure how much nic to add without a calculator is divide your target strength by your nic base strength. In your case, 18 divided by 48 = .375, so roughly 38% of your total volume would be the amount of 48 mg/ml nic base to add. Throwing pg/vg ratios into the equation adds another dimension to your final recipe but does not affect the above calculation as far as how much nic to add.

    It can be somewhat like algebra in that you start with certain known values IE 38% nic, 10% flavor, 15 ml total and then calculate the missing values from there. It can seem daunting at first, but breaking the recipe down to it's individual components all expressed as a percentage of total volume helps and after a while it will be second nature to do the math.

    Example

    15 ml total

    15 x .38 = 5.7 ml of 48 mg/ml nic 50/50 = 2.85 ml pg and 2.85 ml vg (your vg cannot be higher than 19% total without adding additional plain vg. I stay away from 50/50 nic bases as they can sometimes limit your options on your final ratio)

    15 x .10 = 1.5 ml flavor = 1.5 ml pg (assuming pg based flavor)

    15 x .52 = 7.8 ml pg To get this number: VG is at 19% which means PG needs to be 81%. Total pg from the 2 steps above so far is 29% (19% from the nic and 10% from flavor) 81%-29% = 52% or .52

    With such a high pg ratio I wouldn't add more than 3% water, taking that 3% away from the pg or your juice could be too thin and cause leaking or flooding issues. A bit of water does help counter the drying effects and harshness of pg and can help smooth things out.

    Hope this helps. I probably way overdid it and confused you :blink:
     
  15. mrcoolbp

    mrcoolbp Senior Member ECF Veteran

    Cool math zoiDman! I feel like we are close to presenting this in a more readable fashion. Yours is more like a formula, which is good if people can't wrap their brain around it. Mine has less steps, but requires the ability to guess the approximate ratios, and then guess again if wrong (back to more steps).

    It would be nice if we could come up with a slightly more elegant presentation, it might "click" more for people.
     
    • Like Like x 1
  16. zoiDman

    zoiDman My -0^10 = Nothing at All* ECF Veteran

    Supporting member
    Apr 16, 2010
    So-Cal
    That you mrcoolbp. Math is Kinda what I do.

    I'm Not Very Specific Solution Oriented. They are of course desirable for Individual Situations.

    My thing is more finding Open Form Formulas which can be used to Solve Any Situation. That and Seeing/Understand/Presenting the Larger Concepts.

    Like the Relationship of Fractions - Proportions - Ratios - Percentages. Which are all the Same Thing. Just in a Different Form using Different Nomenclature.
     
  17. rebgold

    rebgold Super Member Verified Member ECF Veteran

    Jan 27, 2013
    Wichita, KS
    The easiest way to figure how much nic to add without a calculator is divide your target strength by your nic base strength. In your case, 18 divided by 48 = .375, so roughly 38% of your total volume would be the amount of 48 mg/ml nic base to add. Throwing pg/vg ratios into the equation adds another dimension to your final recipe but does not affect the above calculation as far as how much nic to add.

    Here's what I want to turn this into. 38% is a little over a third, so I could use a third of a cup of 48 mg nic base, a very full, little bit more than a third of a cup really, then a little less than 2/3 of a cup of pg, and a tablespoon of distilled water.
    Or, so I don't sound totally nuts, 1/3 of a cup is about 100 ml, 2/3 of a cup is about about 200 ml, and a tablespoon is about 20 ml.
    The flavoring added is a pretty small amount in each 15 ml bottle, so I'm not concerned with dropping the nic a tiny bit when I add it.
    Does that work? Especially if I don't really care about the exact nic mg as long as it's between 19 and 17?
     
  18. Road_House

    Road_House Senior Member ECF Veteran

    May 12, 2013
    SE PA
    Somewhat unorthodox but should work if you're not hung up on an exact nic strength. Each 5% of flavor added will reduce your nic by
    .9% That's the drawback to a premixed base. Your nic level will drop to 15.3% if you have 15% flavor.

    You are close on the tablespoon to ml conversion. I found this calculation: 1 Tablespoon [US] = 14.7867648 Milliliters. So in 300 ml total, 1 tablespoon would be close to 5% which is not bad in a 70% vg mix. I would add the water after the nic base then top off with the vg up to the full 1 cup mark.

    If you don't have them, consider some 1,3, and 10 ml syringes to measure your base and flavors. Seemingly small changes in flavor percentages can be the difference between meh, yuck and WOW. The difference between 2% and 3% flavor seems trivial when in reality it is a 50% increase which can have a major influence on your juice. The preciseness of syringes also allow an exact repeat performance once you hit the flavor jackpot. :toast:
     
  19. rebgold

    rebgold Super Member Verified Member ECF Veteran

    Jan 27, 2013
    Wichita, KS
    I do have some syringes, but to be embarrassingly honest, I mix by smell.
    I have a rough idea of what I'm trying to get, by smelling all my flavorings and coming up with an idea. I know which I want to be the predominant flavor, then which undertones I want. I start by adding drops, more of the first, less of the second, less of the third, shake and smell. Sometimes I taste it. If it's not what I imagined, I add more drops. It works surprisingly well.
    Go figure I'm not terribly concerned with exact nic levels, lol.
     
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