October 1, 2025

How Much THC Is In A Joint?

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Key Takeaways

The average joint contains between 40 to 200mg of THC, and you can calculate the approximate THC amount by weighing the joint and multiplying by the THC percentage found in the hemp flower's Certificate of Analysis.
Bioavailability significantly affects the amount of THC actually absorbed by the body when smoking a joint, with absorption rates ranging from 2% to 56%, and factors like smoking technique, environmental conditions, and ingesting fats can influence this.
Joint size, THC percentage, and puff technique all impact the amount of THC consumed, so knowing these factors and applying proper smoking methods can enhance the overall experience and THC intake.

If you’re shopping for cannabis flower that fits your needs, you’re likely going to look at factors like the strain and the approximate cannabinoid content. This information can typically be found on the product's packaging. But when it comes time to smoke, how do you determine how much THC is in each blunt?

How Much THC Is In A Typical Joint?

The average joint contains between 40 to 200mg of THC, but some may contain more.

Pre-rolls tend to be popular because you don't have to do the math- the professionals do it for you. But if you like to roll your own joints, we’re here to teach you how to calculate the approximate amount of THC in each one.

How to Calculate the Amount of THC In A Joint?

Suppose you just picked up some cannabis flower and want to roll some joints. How do you determine a rough estimate of the amount of THC within each one?

Materials Needed to Calculate THC Percentage

You can calculate the amount of THC in a joint using a simple mathematical formula. But before you begin, you'll need to gather some tools:

Pen
Paper
Calculator
Kitchen weight scale
Cannabis flower (for example, weed or THCA flower)
The flower's Certificate of Analysis

Once you have everything, you can get started.

Calculate THC in a Joint Step by Step

To calculate the total amount of THC in a joint, start by weighing the rolling paper and filter together on your kitchen scale.
Then zero it out. This will "tare" the scale so that the paper and filter don't affect your calculations.
Take the paper and filter off the scale, and roll your joint.
Place the rolled joint onto the scale and record its weight in milligrams.
Next, refer to the hemp flower’s Certificate of Analysis (COA) to find the percentage of THC in the product.

With the weight of the joint and the percentage of THC, it's time to do some math.

THC in a Joint Formula:

Weight of joint in milligrams x THC percentage in decimal = total milligrams of THC in joint

Example Calculation: 750mg x 0.19 = 142.5mg of THC.

Factors that Affect the Total Amount of THC Absorbed

The above formula will give a rough estimate of the THC in your joints. But remember, it’s not exact.

Some additional variables that can affect the amount of THC that you consume will include:

Smoke wasted from harsh wind
Smoking technique
Bioavailability (which affects the amount of active compounds that the body will absorb).

The first two factors are relatively straightforward.

But what is bioavailability? This term refers to the actual rate of absorption for various substances. When you take vitamins or prescription medication, or smoke cannabis, only a certain amount of compounds within each substance will be absorbed into the body.

The remaining amount will not be absorbed in the gastrointestinal (GI) tract and instead will be converted into waste products. The same process applies to smoking cannabis: Only a portion of the THC you ingest will be absorbed in the body, and because each body is different from the next, there is no way of knowing how much this is.

According to an article in the Journal of Chemistry & Biodiversity, participants who smoked cannabis had a bioavailability ranging from 2% to 56%. This study suggests that the total amount of THC actually absorbed by the body is far lower than one would assume, given the amount of THC in the product.

So, even if a joint has 155mg of THC, you likely won’t be taking in that amount. While you can't completely control this biological function, some food compounds are known to help. Lipids are a great example, since cannabinoids are lipophilic, so consider ingesting fats, like MCT Oil or butter, alongside your cannabis product to improve your body's bioavailability.

Factors That Affect The Amount of THC Consumed

Although bioavailability is a significant factor affecting how much THC you consume, there are several techniques you can try to gain the most THC each session. Below, you’ll find some useful tips and other factors to consider before your next session.

The Size of the Joint

The size of the joint will influence how much THC you consume. Obviously, a smaller joint will have less THC, but the bigger the joint, the more difficult it is to avoid air resistance.

So if you can, try smoking inside. This will put you in a controlled environment that will also combat the devastation of canoeing.

Percentage of THC

When you’re picking out hemp flower or joints, take a look at the percentage of THC and the strain. By looking at both, you can determine which flower is best for you.

If you want a mellow experience, try cannabis with a lower concentration of THC, and vice versa if you’re looking for a more elevated experience.

Puff Technique

How you smoke will affect the amount of THC consumed. If your technique isn’t efficient, you’ll be losing out on many of hemp's cannabinoids. Remember to wait for the joint to light and inhale the next time you light up. Take deep inhales and wait for the effects- but don't think holding it in will do anything.

Final Thoughts

For the best experience, it’s important to know the amount of THC in your products, especially joints. Whether you roll your own or buy pre-rolls, knowing an estimated amount of THC will help determine how much you need. And by applying our techniques to our next session, you will get the most out of your joint.