A common question tokers have about their joints is, "how many milligrams of THC is in a joint?"
The answer isn't as straightforward as you'd like. First, we need to gather a bit of extra information.
After checking online dispensaries, the most commonly sized pre-rolls found for sale in dispensaries are 0.5g and 1g.
But according to research using federal drug arrest data (from 2000 to 2010) published in the journal Drug and Alcohol Dependence in 2016. A joint's average amount of weed was estimated at just 0.32 grams.
This data comes from before the broad legalization of cannabis in the USA. Since then, the average joint size may have increased along with the market and use of marijuana across the US. However, in this article, we will use the 0.32 grams from the study as our baseline.
Different parts of the plant have different concentrations of THC. The stems and leaves have less THC than the bud itself. Let us assume we just use bud with a standard potency. Then you can work out the total milligrams of THC in a joint.
The amount of THC found in weed can vary vastly from different strains of cannabis. THC dominant strains can be anywhere from about 8% to 30% THC content by dry weight. You may occasionally find some strains with higher THC content. The biological limits on THC production mean that THC by dry weight tops out at around 25%.
On average higher THC strains will contain about 15 to 20%, and the "very potent" strains will be around 25%.
Fortunately, any reputable outlets in the USA will have lab-tested cannabis, so the THC content is on the packaging.
If you don't mind a little arithmetic, it is pretty straightforward to calculate the THC in your joint using the THC percentage given on the packaging.
Testing labs use a simple mathematical expression to calculate the theoretical maximum amount of THC in cannabis.
THC max = THC + THCA / 358.48 * 314.47
This expression gives the lab an estimated THC amount in a sample. You will likely see this estimate printed on the packaging of weed you buy from legal dispensaries.
Say you have a joint packed with 0.32g of lemon sour diesel at 18% THC.
Let's convert that 0.32grams to 320milligrams. Since the strain is 18 percent, we multiply 0.18 by 320.
0.18x320 = 57.6 milligrams of THC
Even if we know the strength of the cannabis strain and calculate the maximum amount of THC in a joint, that isn't how much you will consume in your smoking session.
There are four factors that determine how many milligrams of THC you can consume when smoking a joint. These are potency, joint size, bioavailability, and smoker's physiology.
This is where it gets a little complicated. There can be a notable difference in how much THC is in your weed and how much THC you consume.
Our lemon sour diesel joint containing 57.6mg of THC does not mean you would ingest the entire 57.6mg.
This difference between potential THC and THC available to be consumed is down to the availability of THCA (THC in its non-psychotropic form) in an unlit joint. Some of this will be lost when we burn the cannabis; it will literally go up in smoke.
The THCA is converted to THC when ignited. This is known as decarboxylation and describes the removal of carboxyl from THC acid.
The temperature and amount of time it takes for decarboxylation to occur determine the total milligrams of THC you can consume from one joint.
Approximately 40% of THC is lost when smoking a joint. This means we could get 0.6x57.6mg, at most 34.56mg of THC.
If you smoke weed from a bong bowl or hand pipe then you will have less wastage from the weed burning off and that smoke not being consumed. A vaporizer will have even less wastage as it doesn't combust so none of the THC is lost in the burning/heating process.
Consuming the entire amount of THC in a joint would be impossible. Bioavailability, the amount of a cannabinoid that makes its way into a body's circulation after consumption, also plays a big part.
The bioavailability of inhaled THC is anywhere from 10% to 35%
So even if we use the best figure of 35%, you would consume around 12mg of THC from the 0.32gram joint of lemon sour diesel. This also assumes that you inhale every bit of smoke from the joint, which is unlikely, even if hotboxing.
Everyone's body chemistry is different. Age, health, diet, and many other factors play a part. This means there is no standard way the body breaks down or tolerates THC.
How your body consumes and processes THC is determined by several factors, such as lung capacity and how much THC is exhaled with the smoke. Contrary to popular belief holding the smoke in your lungs for longer than a few seconds will not increase THC absorption. However, taking deep full breaths as you inhale will bring more smoking into your lungs and help improve your THC absorption when smoking a joint.
Additionally, you should remember that those not used to smoking react differently to THC than regular or consistent users.
The more you consume cannabis, the higher your tolerance gets; hence, the more THC your body can handle. Also, users react differently to THC, regardless of the strain's potency.
If you don't have the patience to do these calculations, a more leisurely, though expensive way to determine how much THC you've consumed accurately is through blood tests. That's the only way to know for sure.