Devising a THC formula to calculate detection time

Discussion in 'Urine Testing' started by V-te, May 29, 2010.

  1. V-te

    V-te Active Member

    I want to know if it'll be possible to take into account all of the important variables, and mathematically piece them together to make a formula that can give you a precise answer.
    First thing would be to get together all the important variables.

    Personal Variables:
    Body fat %
    Weight (How would weight affect it? I guess it really depends on how many pounds of fat you have, since THC is fat soluble)
    Age (Connected to metabolism; younger faster, older slower. Metabolism will be in the equation)
    Height? ( Again, do not think it's important but will put it anyways)
    Diet- Apparently not important due to metabolism burning what you eat and what you have. So we can say that if you eat less, you'll use more of your own body fat and clean sooner?
    Frequency of smoking

    Weed Variables:
    How much consumed
    Method of consumption (As some THC is lost depending on the method)
    ~% of THC
    Half-life of THC - 20 hrs-10 days. (Would it be reasonable to assume that stronger strains have a faster half life?)

    Consumption variable constants:
    Bong- 0.6-0.7 depending on cleanliness and ignition source
    Pipe- 0.4-0.5 depending on cleanliness of pipe
    Joint- 0.1 - 0.2 depending on size,and quality of the hit
    Blunt- Same as joint?
    Bubbler- Same as bong?
    Edible- 1.0

    The method of consumption is important because it will let us know how much of the THC from the plant is actually getting to us, thus giving us a more accurate measure. These numbers are the percentages of THC extracted from the plant. If they are inaccurate, please let me know.

    Now, the hard part would be to figure out how it all mathematically fits together to come out with a working formula, This is where I need tips and knowledge I might not personally have. From a first look, it seems that all of the math needed will be simple multiplication/division and plugging in.
    Now that we seem to have most of the variables, I guess we can start finding a correlation of the variables.
    First, I'll state what is known (feel free to suggest more):

    * THC is dissolved in fat. (THC/g fat)
    * Half of the THC is lost in minimum 20 hrs and maximum 10 days, so we're going to get a minimum answer and a maximum answer (Inequality)
    * Frequency of smoking can be calculated as addition of grams smoked. (1 gram today, half yesterday= 1.5 grams) Taking into account the slight loss of THC in the amount of time not smoked.
    * ????

    Here, let's start a rought draft of the formula.
    First, let's find out how much THC you consumed:

    THC consumed = Gc * %THC * Mc

    Gc= grams consumed
    %THC= Percentage of THC in the plant (Depending on the strain;You can usually google this if you know the strain)
    Mc = Method of consumption variables (Listed above)

    From there, we know how much THC can be absorbed into our body fat. Going to work on this.


    I want to make this a collaborative project so if you can figure it out, or contribute, that would be great. Any first contributors? or constructive criticism? Please let me know if I'm missing any variables. Thanks, this is a work in progress.
  2. k_semler

    k_semler Sr. Member

    Hieght/weight ratio, (rough figure of BMI would be important, so that consolidates 3 variables, (height, weight, body fat).

    The half life of THC is anywhere between 20 hours and 10 days, (depending upon potency, and how much consumed).

    The fattier products that you ingest, the more the molecules of THC have to stick to. If you eat a tub of lard for dinner, verses vegatarian, the person eating the tub of lard will retain THC at a longer rate then a peron on a vegetable, high protien, water diet, with only the minimum fat nessecary to keep a person healthy.

    Metabolism. The faster one burns off energy, the faster the person will excreet THC from the blood stream faster
  3. V-te

    V-te Active Member

    How could we represent metabolism in a number? I take it that any number that we get is going to be divided by this number.

    To find the number of THC in the strain, we can estimate based on information found on the strain.
    Say we have high quality stress, that can be 5% THC. If I smoke about half a gram, then we can find out how much THC is in our system by multiplying 5% (0.05) with half a gram (0.5), giving us a final answer of 0.025. This number would then further be multiplied with the amount of THC actually taken depending on the method of consumption. We're going to need average constants for Bongs,Joints,Vapes,Bubblers,Pipes. Eating it is almost 100% of it, so if it is consumed, that number will just be 1.

    Also does anyone know much much THC actually metabolizes into Metabolites? If not, we're gonna have to make an estimate.
  4. Buzzby

    Buzzby Buddhist Curmudgeon

    Can you cite a source for that? From everything I've read, half-life is highly variable only because of the people's differing metabolism rates.
  5. Secs

    Secs New Member

    Some things are just too complicated to assess a simple mathematical formula. The variables for any one person can change from day to day depending on activity level, diet, fluid intake, time of day, etc...

    In addition to what you have mentioned above, there is the THC content of the weed used. Some strains are more potent than others and this can change from purchase to purchase. Height and weight do matter. It isn't how much fat you eat, but how much fat you carry on your body that matters. Age also is important because typically a younger person has a higher rate of metabolism than an older, more sedentary person. All of this can change daily on any one person.
    2 people like this.
  6. V-te

    V-te Active Member

    I believe that half-life is just the chemical in itself and it can vary depending on the potency of the strain. The metabolism will affect the rate of excretion, but not really the half-life itself.
    I think it is mostly true, as I've been reading of people passing a test after smoking the night before, and others not passing after a prolonged period of time. So it seems like an educated estimate. Here is the source he got it from

    Yeah, I understand that it is technically impossible to calculate this mathematically but what I'm trying to get at here is to take all that we can calculate, and try to get close. Similar to the Drake Equation, but more accurate considering we have more information available. Thanks for your other information about weight and age. We can connect age to metabolism as one now. =)
  7. k_semler

    k_semler Sr. Member


    HowStuffWorks "Other Effects of Marijuana"
  8. califdude

    califdude New Member

  9. k_semler

    k_semler Sr. Member

    I disagree. Not on empirical evidence, but on subjective experience. In the consolidated figures I provided above, elimination of variables that I could consolidate into one formula were merged. With the formula discounted to simple mathematics, that is the only way it can be practiced.
  10. V-te

    V-te Active Member

    Actually, I read the article, It's pretty informative and not really biased. The one about cocaine and heroin are more biased, and I wouldn't be using it if it seem biased.
  11. duckmn56

    duckmn56 New Member

    I really appreciate this type of work. A very good thing to do, which may be difficult would be to collect all of the data from users of this site for the information they can provide. Of course a cautious in site would be needed to determine when the person was clean. Basically if we could gather empirical evidence and somehow compile it to use as a comparison to the equation to help support its accuracy.

    I you need any help PM me I would be happy to help since this seems like a project that may take some work.
  12. Secs

    Secs New Member

    I'm not saying that you can't assess a number to a given metabolic rate or age, or quantity of pot used, etc and come up with a formula... the problem is assessing an accurate number to any one person accurately. Since people change activity levels, quantity of pot used, dietary intake, etc... daily; assessing an accurate number at any point in time would be tricky and inaccurate at best.
  13. duckmn56

    duckmn56 New Member

    Yes I agree a degree of inaccuracy will always occur because people are biological and because of that the complex systems will cause variety in addition to the other possible variables. However given a set of inputs that are known. An estimation can be made. Of course the accuracy of this estimation can be questioned and then you can use empirical data to compare how accurate your equation is at those specified variables.

    Another way to do it is to collect data of all the variables and make an equation from that data.

    For both of these the accuracy of the equation, and data will be dependent on the accuracy of the known or assumed values for the variables.

    A specific day/hour/etc... for any variety of situation may not be able to be solved for exactly at this point, but from what there is now it can be alot better. Also, if work is done on this future work can be done using the experience/data/etc..or use this as a comparison.

    I hope it works out and isnt given up before a decent equation/estimation is made.
  14. V-te

    V-te Active Member

    Great Idea. That would be a nice way to test the formula's accuracy. Another thing that came to my mind is that the answer would only be if your lifestyle remains the same. So if you workout, the number can be lower than the answer, but still close.

    I suppose we can start by finding out how much THC you consumed. Edited the first post, it's there, give me opinions, it's just a rough draft.
  15. gremlinkurst

    gremlinkurst New Member

    Of course one must keep in mind that in order to be precise regarding exact dosage, not only is it imperative that plant species be the same, but as well must be the cycles for the growth term and nutrient saturation (growths/yields/crops). Further study of Chemistry, Genetics, Physics, Biochemistry, Biogenetics (blah, blah, blah) would eminently illuminate the subject.
  16. TheTruthIsOutThere

    TheTruthIsOutThere New Member

    It's been over 5 years - where did everyone go? The formula/calculation jargon is exactly what I've been looking for. The thing is, if this thread is no longer being commented on then I don't see the point in sharing my thoughts... factors calculated in the formula and the result of a urinalysis.
  17. Buzzby

    Buzzby Buddhist Curmudgeon

    I think it's pretty obvious that the determination of detection time has many variables, many of which are impossible for anyone without a fully equipped medical laboratory to measure, if then. If we have to guess at the values for the variables, any formula would be meaningless.

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