The THC in regular weed is delta-9-tetrahydrocannabinol, commonly written as delta-9-THC or just THC. It’s the main psychoactive compound in cannabis and the one responsible for the high. While the plant contains over a hundred other cannabinoids, delta-9 is the dominant one that matters for potency and effects.
Delta-9-THC Starts as an Acid in the Plant
Here’s something that surprises most people: the living cannabis plant doesn’t actually contain much active delta-9-THC. Instead, it produces THCA, the acid form of THC. THCA binds very weakly to the brain’s cannabinoid receptors compared to delta-9-THC, which means raw cannabis flower won’t get you high in any meaningful way.
THCA converts into active delta-9-THC through a process called decarboxylation, which is just a fancy word for “applying heat.” When you light a joint, use a vaporizer, or bake cannabis into edibles, the heat strips a carbon group off the THCA molecule and turns it into the delta-9-THC your body can use. In lab studies, THCA fully converts to delta-9-THC in about 6 minutes at 145°C (293°F) and around 30 minutes at 110°C (230°F). This is why smoking works instantly but edible recipes call for “decarbing” your flower in the oven first.
How Potent Is Delta-9 in Today’s Flower
Cannabis has gotten dramatically stronger over the past few decades. Flower harvested in the 1990s averaged about 5% THC. Today’s strains average 15 to 20%, with some testing as high as 35%. In Washington State, the average THC concentration for flower sold in dispensaries was 21% in 2022. When you see a THC percentage on a dispensary label, that number represents the combined total of THCA (which will convert when heated) and any already-active delta-9-THC in the flower.
What About Delta-8 and Delta-10?
You’ve probably seen delta-8-THC and delta-10-THC products in gas stations or smoke shops, and you might wonder if those are naturally in weed too. They exist in the cannabis plant, but only in trace amounts, far too small to produce any noticeable effect. Nearly all commercial delta-8 and delta-10 products are manufactured by chemically converting CBD (usually from hemp) through an industrial process called acid-catalyzed isomerization. These are not the same thing as what’s naturally in regular cannabis flower.
Other Minor Cannabinoids in Regular Weed
Cannabis contains a few other THC-related compounds worth knowing about. THCV (tetrahydrocannabivarin) is a naturally occurring cannabinoid found in certain strains, particularly sativa varieties with African genetic origins. Unlike delta-9-THC, THCV doesn’t produce a strong high at typical doses. It actually works against THC at the brain’s CB1 receptors rather than activating them, which means it can dampen some of THC’s psychoactive effects. THCV has also been linked to appetite suppression, the opposite of THC’s famous “munchies” effect, along with reduced anxiety and increased alertness.
Most regular weed contains only small amounts of THCV unless the strain was specifically bred for it. CBD, the other well-known cannabinoid, is present in varying amounts depending on the strain but is non-intoxicating and often bred out of high-THC varieties.
How Your Body Processes Delta-9
The way you consume cannabis changes what delta-9-THC becomes inside your body, and this explains why edibles feel so different from smoking. When you inhale, delta-9-THC passes quickly from your lungs into your bloodstream and reaches your brain within minutes. When you eat it, the THC travels to your liver first, where it gets converted into a metabolite called 11-hydroxy-THC. This metabolite is also psychoactive and crosses into the brain more efficiently than delta-9 itself. That’s why edibles often feel stronger and longer-lasting even at the same dose.
Oral THC also has low bioavailability, only about 6 to 10% of what you swallow actually reaches your bloodstream, because much of it gets broken down during digestion and that first pass through the liver. The ratio of 11-hydroxy-THC to delta-9 is significantly higher after eating cannabis than after smoking it, which contributes to the more intense, longer-duration experience.
The Legal Line Between Hemp and Weed
Federal law in the United States draws the line between hemp and marijuana at exactly 0.3% delta-9-THC by dry weight. Cannabis below that threshold is legally classified as hemp. Anything above it is marijuana, which remains federally controlled. This single number is why the hemp-derived cannabinoid market exists at all. Products made from hemp can legally contain delta-8, CBD, and other cannabinoids as long as the source plant stayed under 0.3% delta-9-THC. Regular weed from a dispensary, by contrast, typically contains 50 to 100 times that amount.