Calculating a Dose

Short Story:  Always find the mg/g or mg/ml to accurately compare cannabis meds.  But know it is an estimate in the end.  Whether or not you have test results, always start with a very small amount.


Long Story:  Percentages, ratios, mg's, oz's, grams, what does it all mean?  Test results of cannabinoids from labs are generally given in a percentage.  This percentage is the amount of a given cannabinoid per gram or milliliter of the product .  Already confused.  I know.  So let's stop using percent and move to mg/g.


Convert the percent to mg/g simply by removing the percent sign and multiplying this number by 10.


Examples:  17% = 170 mg/g,    5.5% = 55 mg/g,  .7% =  7mg/g


If it is flower you have 170mg of THC in one gram of flower.  If it is a bottle you have 170 mg per gram of oil.  A gram equals a ml.  Easy?


If your product is in a bottle and is already in mg/g - great!


If your product is in a bottle and is in mg per bottle take the mg and divide by the number of ml.  Usually this number is on the bottle.  The most common are 15ml and 30ml.  If it is reported in oz multiply the ounces by 30.


Examples:  30 mg in a 1 oz bottle  = 30 mg / 30 ml = 1mg/ml,  40 mg in a 15 ml bottle = 40 mg / 15 ml = 2.6 mg/ml.


Those of you in any country besides the US will find this much easier.


Now, if you are buying flower to make your own medicine, there is a formula you can use to determine the estimated amount in your concentrated extract.  We will simply use a dilution equation.

  • C1=concentration of original solution in mg/g or percent (might as well start off with mg/g.  So move your decimal if you are working with a percent)

  • V1=volume of original solution

  • C2=concentration of new solution

  • V2=volume of new solution

  • (C1)(V1)=(C2)(V2)

Plug in your known variables to get the unknown.  Your known concentration is either on your label or on the lab paperwork.  Most of the time you will be finding C2 or the concentration of your new solution.    Here are some useful conversions.

  • mg/g= C1%  x 10

  • 1 gram=1 ml

  • 1 ml=20 drops

  • 15 ml=240 drops

Once you know the mg per ml you can go further down to the drop.  If you know how many mg are in your entire bottle simply divide TOTAL MG/TOTAL ML= MG/1ML.  To break this down further into drops divide by 20.  There are approximately 20 drops per mL.  This is especially useful for small children.  My daughter takes 4 drops of her medicine which is approximately 4 mg of CBD and about 1 mg of THC.  When I make a new batch and get that tested, knowing a ballpark of her current dose is important so I can figure out more or less how it will compare.


Longer story: I am trying to get a conversion widget--let me know if you can help!