If you’ve looked closely at a cannabis label, you’ve probably noticed that THC isn’t always the only cannabinoid listed. You may also see THCA, sometimes in a surprisingly high percentage.
So what’s the difference between THC and THCA? And if THCA can become THC, why are they listed separately in the first place?
The short answer: THCA is the acidic precursor to THC. Heat converts THCA into THC through a process called decarboxylation. That’s why raw cannabis flower can contain a lot of THCA while having relatively little THC before it is heated.
Understanding that relationship can make cannabis labels a lot easier to read, especially when you’re comparing flower, concentrates, and other cannabis products.
What Is THC?
Delta-9-tetrahydrocannabinol (commonly abbreviated as THC) is the primary intoxicating cannabinoid in cannabis. It is the specific compound most commonly associated with the high produced by cannabis consumption. . For a closer look at how THC compares with another major cannabinoid, check out our guide to THC vs. CBD.
When cannabis is consumed in a form where THC is available to interact with the body’s cannabinoid receptors, THC can produce intoxicating effects. The amount of THC in a product is therefore one of the numbers consumers commonly look at when evaluating cannabis potency.
But there’s another number that can be just as important on certain products: THCA.
What Is THCA?
THCA, or tetrahydrocannabinolic acid, is the acidic precursor to THC. Cannabis plants naturally produce and store cannabinoids in acidic forms, including THCA.
Fresh cannabis flower can contain substantial amounts of THCA and comparatively small amounts of THC. THCA itself does not produce the same intoxicating effect as THC in its raw acidic form. When heat is applied, however, THCA can undergo decarboxylation and convert into THC.
That’s an important piece of the puzzle when you’re looking at the numbers on a cannabis label.
THC vs. THCA: What's the Difference?
The easiest way to think about the relationship is this:
| THC | THCA | |
|---|---|---|
| What is it? | The primary intoxicating cannabinoid in cannabis. | The acidic precursor to THC. |
| What does the % mean? | The percentage of THC already present in the product. | The percentage of THCA present in the product before heating. |
| What happens when heated? | THC remains THC, although excessive heat can degrade cannabinoids. | THCA can convert into THC through decarboxylation. |
| Why does it matter when shopping? | It tells you how much THC was measured in the product. | It helps explain why cannabis flower can show a high THCA percentage alongside a lower THC percentage. |
| What should you remember? | THC is the cannabinoid most associated with cannabis's intoxicating effects. | THCA is not the same as THC, but heat can convert THCA into THC. |
THCA and THC are closely related, but they aren’t interchangeable. The chemical difference between them affects how the compounds behave, including what happens when cannabis is heated.
Does THCA Get You High?
THCA in its raw acidic form does not produce the same intoxicating effect as THC. The important distinction is what happens when THCA is exposed to heat.
Smoking and vaporizing cannabis provide enough heat to promote decarboxylation, converting THCA into THC. Heating also occurs when cannabis is baked or otherwise processed with sufficient heat.
That means seeing a high THCA percentage on a flower label does not mean the flower contains that same percentage of already-active THC.
Instead, some of the THCA can be converted into THC when the cannabis is heated.
How Does THCA Become THC?
The conversion from THCA to THC is called decarboxylation.
The name sounds complicated, but the basic idea is fairly simple. THCA has an additional carboxyl group in its molecular structure. When heat is applied, that group is removed as carbon dioxide, leaving THC behind.
You can think of it as:
THCA + heat → THC + carbon dioxide
This process happens naturally to some degree over time, but heat speeds it up considerably. Smoking, vaporizing, and baking cannabis all involve heating the plant material or cannabis extract, which promotes decarboxylation.
The conversion isn’t perfectly 1:1 by weight. THCA loses mass during the conversion process, which is one reason you can’t simply add the THCA percentage and THC percentage together to determine the amount of THC that could ultimately be produced.
Why Is THCA Listed on Cannabis Labels?
If THCA can become THC, you might wonder why cannabis labels list the two separately.
The answer comes down to what is actually present in the product when it is tested.
Cannabis flower naturally contains THCA. Laboratory testing can measure the amount of THCA and the amount of delta-9 THC separately, giving consumers a more complete picture of the product’s cannabinoid profile.
Massachusetts law defines a cannabis product’s cannabinoid profile to include the amounts of delta-9 THC, CBD, THCA, and CBDA, expressed as dry-weight percentages. Current Massachusetts adult-use regulations also require marijuana-product labels to include the product’s cannabinoid profile.
So when you see both THC and THCA on a cannabis label, you’re not looking at two unrelated versions of the same number. You’re seeing two different forms of cannabinoids that exist in the product.
If you’re still getting familiar with cannabis packaging, take a look at our guide to how to read a cannabis product label for a closer look at the information you’ll find on a dispensary label.
What Does THCA Percentage Mean?
A THCA percentage tells you how much THCA was measured in the product relative to its total weight.
For example, imagine a cannabis flower label showing:
THC: 1%
THCA: 25%
That does not mean the flower contains 26% THC in its current form.
It means the laboratory measured approximately 1% delta-9 THC and 25% THCA in the product.
Because THCA can convert to THC when heated, the THCA number can still be relevant when thinking about the product’s potential THC content after decarboxylation. But the two percentages should not simply be added together.
Does Higher THCA Mean Stronger Cannabis?
Not necessarily.
A high THCA percentage tells you that the flower or product contains a relatively high concentration of THCA. It does not, by itself, tell you exactly how a person will experience the cannabis.
For one thing, the amount of THCA that actually converts to THC depends on factors including how the cannabis is processed and heated. Research on decarboxylation has shown that the conversion of THCA to THC depends on factors such as temperature and heating time, and that the conversion is not always complete under every set of conditions.
There is also more to a cannabis product than a single cannabinoid percentage. The overall cannabinoid profile, product format, and other characteristics can all be relevant when comparing products.
In other words, THCA is an important number to understand, but it is not the sole indicator of how high a product may get you.
What Is Total THC?
This is where cannabis labeling can get especially confusing.
The term total THC is used to account for both the THC already present and the THC that could result from converting THCA.
Because THCA loses mass when it becomes THC, the calculation isn’t simply:
THC + THCA = total THC
Instead, a commonly used calculation is:
Total THC = THC + (THCA × 0.877)
The 0.877 factor accounts for the difference in molecular weight between THCA and the THC produced through decarboxylation. Massachusetts uses this formula in its hemp guidance when calculating total THC.
For example, if a product contained:
1% THC
25% THCA
the theoretical total THC calculation would be:
1 + (25 × 0.877) = 22.925%
That does not mean you should expect to experience exactly 22.925% THC after consuming the product. Real-world decarboxylation is not perfectly complete, and the calculation is a way of accounting for the relationship between the two cannabinoids rather than a guarantee of what will be delivered to the body.
This distinction is especially important when comparing different labeling systems or trying to make sense of potency numbers across different types of cannabis products.
THC vs. THCA: What Should Cannabis Consumers Know?
If you’re standing in a dispensary and looking at a cannabis label, there are a few key points worth remembering.
THC and THCA are different forms of cannabinoids. THC is the primary intoxicating cannabinoid associated with the cannabis high, while THCA is its acidic precursor.
Cannabis flower can contain a lot of THCA. The plant naturally produces and stores THCA, which is why the THCA percentage on a flower label can be much higher than the THC percentage.
Heat changes the equation. Smoking, vaping, and other forms of heating promote decarboxylation, converting THCA into THC.
THCA and THC percentages shouldn’t simply be added together. THCA loses mass during decarboxylation, which is why calculations that account for potential THC use a conversion factor rather than treating the numbers as interchangeable.
Most importantly, don’t treat a single percentage as the whole story. Understanding what the numbers actually represent gives you more useful information than simply looking for the highest number on the label.
The Bottom Line
THC and THCA are closely connected, but they aren’t the same thing.
THCA is the acidic precursor to THC. Heat causes THCA to decarboxylate, converting it into THC. That’s why cannabis flower can have a high THCA percentage even when its measured THC percentage is much lower.
Once you understand that relationship, the numbers on a cannabis label start to make a lot more sense. And when you’re comparing products, THCA is an important number to understand, but it is not the sole indicator of how intoxicating a product may be.
If you’re shopping for cannabis in Ayer, Massachusetts, Gage Cannabis Co. offers a wide selection of quality adult-use cannabis products at accessible prices. You can browse the current Gage menu to compare products before your visit or place an order online for in-store pickup.
Not sure what you’re looking for? Our knowledgeable team is here to help you understand the products you’re considering and answer questions along the way. Visit us at:
Gage Cannabis Co.
38 Littleton Rd.
Ayer, MA 01432
We’re open 9 AM–10 PM every day.
