How Much THC is in a Joint and How Much THC is Absorbed When Smoking?

Some of the most common questions around smoking cannabis are how much do I need to smoke to get high, how much THC is in a joint, and how much do I consume when smoking one? 

The question of how much THC is in a joint is more complex than it might seem. Determining the exact amount of THC consumed involves factors like joint size, the THC/THCA content of the cannabis, the process of combustion, and the bioavailability of THC in the body.

While each individual's experience with cannabis will be different depending on a range of variables, such as tolerance, age, body fat, etc., in this article, we will try to explore the variables around how the body absorbs THC and how much THC you're really consuming when smoking a joint compared to vaping or smoking a bowl.

How Much Weed Is Typically in a Joint?

The size of a joint is a main factor in circulating how much THC it contains. The most common sizes prerolls contain 0.5 and 1 gram of flower, whereas many people who roll themselves make 0.3 gram joints:

1. 0.3 grams: This was the average size of a joint, according to a 2016 study using federal drug arrest data.
2. 0.5 grams: A standard "half-gram" joint is a popular size for prerolls available in dispensaries.
3. 1 gram: Larger joints are also commonly sold as prerolled. These are often shared among multiple users.

For the purposes of calculation, we'll use a 0.3-gram joint as the baseline, though actual sizes may vary depending on the user's preferences or regional norms.

Calculating the THC Content of a Joint

The THC in cannabis exists primarily as tetrahydrocannabinolic acid (THCA) in raw plant material. THCA converts to THC through decarboxylation, a chemical reaction triggered by heat. Here's how the amount of THC is calculated:

1. Determine the THC percentage: Most cannabis strains contain between 15% and 25% THC by dry weight, with some higher-potency strains reaching around 30%.
2. Multiply by the joint's weight: Convert the joint's weight from grams to milligrams (e.g., 0.3 grams = 300 mg) and multiply by the THC percentage.

For example:

A 0.3-gram joint of cannabis at 20% THC contains 300 mg×0.20=60 mg of THC.

THCA to THC Conversion

When cannabis is burned, decarboxylation removes a carboxyl group from THCA, converting it into active THC. However, this process is not 100% efficient. The theoretical conversion efficiency is about 87.7% due to molecular weight differences. Labs use the following formula to estimate total THC content:

THC (total)=THC+(THCA×0.877)

Thus, if a strain is labeled as containing 18% THCA and 2% THC, the total THC is:

0.02 + (0.18 \times 0.877) = 0.02 + 0.15786 = 0.1778 or 17.78%

THC Calculator

How Much THC Is Consumed?

Not all the THC in a joint reaches your bloodstream. Here's why:

Loss Through Combustion

When a joint is burned, a significant amount of THC is lost. Approximately 40% of the THC in cannabis is destroyed by the intense heat or escapes as sidestream smoke while the joint burns. This inefficiency occurs because combustion involves uncontrolled, high temperatures that can degrade THC and other cannabinoids before they are inhaled. Additionally, some smoke dissipates into the air between puffs, further reducing the available THC.

Smoking with a bong or bowl is more efficient than smoking a joint because there is less continuous burning of the cannabis, so less is burnt off in sidestream. 

In a joint, the cherry (the burning end) remains lit and burns away cannabinoids even when not actively inhaled. In contrast, a bong or bowl only burns the cannabis when directly exposed to a flame, minimizing sidestream smoke. 

This difference can reduce THC loss to around 30% with a bong or bowl, compared to 40% with a joint. Furthermore, bongs allow for larger, concentrated hits, potentially increasing the efficiency of THC delivery with each inhalation.

Bioavailability

Bioavailability refers to the proportion of THC that enters the bloodstream. For inhaled THC, bioavailability ranges between 10% and 35%, depending on factors like smoking technique and lung capacity. Using the higher end of this range (35%):

• From 36 mg of available THC, only about 12.6 mg is absorbed into the bloodstream.

Loss of THC with a Dry Herb Vaporizer

A dry herb vaporizer is one of the most efficient ways to consume cannabis because it heats the plant material to a precise temperature below the point of combustion, typically between 315°F and 440°F (157°C to 227°C). This temperature range is sufficient to decarboxylate THCA into THC and vaporize cannabinoids and terpenes without burning the plant material. Unlike smoking, vaporization avoids the destructive effects of combustion, preserving more THC.

When using a vaporizer, less than 10% of the THC is lost during the process. This means a dry herb vaporizer can deliver up to 90% of the THC present in the cannabis to the user. For comparison:

• A joint with 60 mg of THC delivers approximately 12.6 mg to the bloodstream due to combustion and bioavailability losses.
• The same 60 mg of THC in a vaporizer could deliver closer to 30-35 mg, thanks to the reduced THC loss and the higher bioavailability of vaporized cannabinoids.

This preservation of THC makes vaporizers an excellent option for those seeking efficiency, as well as a cleaner and more flavorful experience since terpenes are not destroyed by combustion. Additionally, vaporizers produce less harsh smoke, which may be easier on the lungs compared to joints, bongs, or bowls.

Comparing THC Consumption: Joints vs. Vaping

Cannabis oil vape cartridges offer another alternative to smoking joints. Here's how they compare:

THC Content in Vape Carts

510 Vape carts typically contain concentrated cannabis oil with 60% to 90% THC. A single puff from a vape delivers approximately 3-5 mg of THC, depending on the potency of the oil and the size of the inhalation. Vape carts are one of the most popular ways to enjoy weed as they screw directly onto 510 vape batteries and are relatively cheap and easy to use. 

For more information, read our articles on

Weed vape pens and how many puffs it takes to get high.

How much do vape carts cost?

Efficiency of Vaping

Vaping oil also avoids the combustion process, so less THC is lost, and there is minimal sidestream loss. Oil vapes have a bioavailability closer to 50%, making them more efficient than joints. For example:

• A single puff delivering 5 mg of THC could result in 2.5 mg absorbed into the bloodstream, similar to smoking a small portion of a joint.

Comparison to a 0.3-gram Joint

A 0.3-gram joint with 20% THC contains about 12.6 mg of THC absorbed into the bloodstream. This is roughly equivalent to 4-5 puffs from a vape cart.

How Much Weed Should I Smoke/Vape?

Knowing how much cannabis to smoke or vape is crucial to finding the right balance; too much weed could leave your head spinning and you feeling ill and not having a pleasant time. In order to find the right balance and have a good experience, we recommend the following doses. 

Beginniner: if it is your first time-consuming weed, we recommend 5 to 7 mg of THC. This is about 2 or 3 puffs on a joint or 2 puffs on a vape pen. 

Inexperienced: if you don't consume weed often and have a low tolerance then we recommend 7 to 10 mg of weed. This is 3 to 5 puffs from a joint or 3 or 4 puffs on a vape pen.

Experienced: if you're experienced and have a moderate tolerance, then you will likely need a little more to get the desired effects. We would advise around 10 to 20mg of THC. This is around 6 to 10 puffs on a joint or 5 to 8 puffs on a vape pen. 

More experienced: If you are more experienced and consume weed regularly with a high tolerance, then you may find you need 20mg, 30mg, or more to reach the desired effects. This could be equivalent to a 0.5-gram joint or more or a dozen or more puffs on a vape pen. Just remember to go slow and don't rush. 

When consuming cannabis, it is important to start low and go slow. So, take a few puffs and wait around 10 to 15 minutes to gauge the effects before taking more. 

Conclusion

The amount of THC in a joint depends on its size, the strain's potency, and the efficiency of consumption. A typical 0.3-gram joint with 20% THC might deliver 12.6 mg of THC to the bloodstream, though individual factors like lung capacity and tolerance can affect this. Compared to vaping, joints are less efficient, as combustion reduces available THC. Conversely, a few puffs from a high-potency vape cart or using a dry herb vaporizer can deliver a similar dose with less waste, higher efficiency, and a cleaner experience that is better for your lungs.