Decarb, short for decarboxylation, is the process of using heat to convert the raw, inactive compounds in cannabis into the active forms that produce psychoactive and therapeutic effects. Cannabis plants don’t actually make significant amounts of THC or CBD directly. Instead, they produce acid versions of these compounds (THCA and CBDA) that need to lose a molecular fragment before they become active. That fragment is a carboxyl group, and when it detaches, it leaves as carbon dioxide. Heat is what triggers this reaction.
When you smoke or vape cannabis, decarboxylation happens instantly from the flame or heating element. But if you’re making edibles, tinctures, or infused oils, you need to decarb the cannabis first, or you’ll end up with a product that has little to no effect.
Why Raw Cannabis Doesn’t Get You High
Cannabis plants primarily synthesize THCA and CBDA, the acid precursors to THC and CBD. These acid forms have no psychoactive effects. Eating raw cannabis flower, no matter how potent the strain, won’t produce a high because THCA can’t interact with your brain the same way THC does.
The acid forms aren’t useless, though. THCA and CBDA show evidence of being more potent anti-nausea compounds than THC and CBD. But for the effects most people are after, you need to remove that carboxyl group through heat.
How Temperature and Time Work Together
Decarboxylation isn’t instant. It’s a balance between temperature and time: higher heat works faster, but too much heat destroys the compounds you’re trying to activate. Research optimizing this process for commercial cannabis production found these ranges to be most effective:
- THC-dominant strains: 131°C (268°F) for about 65 minutes maximizes total cannabinoid yield. If speed matters more, 137°C (279°F) for 57 minutes works well.
- CBD-dominant strains: 131°C (268°F) for about 102 minutes for best yield, or 149°C (300°F) for 41 minutes when time is limited.
Notice that CBD strains need more time. THCA converts to THC faster than CBDA converts to CBD, so if you’re working with a CBD product, patience matters more. THCA responds best to shorter times at slightly higher heat, while CBDA does better with longer times at lower heat.
What Happens if You Go Too Hot
Above 160°C (320°F), THC starts converting into CBN, a cannabinoid associated with sedation rather than the typical THC high. In one study, heating THC at 200°C caused nearly 30% of the degraded THC to convert into CBN, compared to less than 10% at 120°C or 160°C. At temperatures between 200 and 250°C, THC begins to decompose outright.
The practical takeaway: stay below 160°C (320°F) for THC-dominant cannabis. CBD strains are slightly more forgiving since CBN wasn’t observed in CBD samples at those temperatures, but total cannabinoid content still dropped at 160°C and above.
Terpene Loss During Decarbing
Terpenes are the aromatic compounds that give cannabis its smell and flavor, and many of them boil off well before decarboxylation finishes. The most common monoterpenes, including myrcene (168°C), limonene (176°C), and pinene (155°C), have boiling points right in the decarb range. Research on cannabis extracts found that about 90% of monoterpenes are lost during processing.
Heavier sesquiterpenes like caryophyllene (263°C) and humulene (276°C) survive better because their boiling points sit well above typical decarb temperatures. If preserving flavor and aroma matters to you, lower and slower decarb settings help retain more terpenes, though some loss is unavoidable.
Oven Method
The most common home method is spreading ground cannabis on a baking sheet and placing it in an oven at around 250°F (121°C) for 30 to 60 minutes. The biggest problem with this approach is temperature inconsistency. Most home ovens swing about 20 degrees above and below the set temperature as they cycle on and off. That means setting your oven to 250°F could expose your cannabis to temperatures anywhere from 230 to 270°F during the process.
Using an oven-safe enclosed container provides insulation and buffers against these swings. An oven thermometer placed inside helps you verify what temperature you’re actually getting. Spreading the cannabis in an even, thin layer ensures more uniform heating.
Sous Vide Method
Sous vide uses a water bath with a precision immersion heater, giving you exact temperature control that ovens can’t match. The process involves sealing cannabis in a plastic bag with all air removed, then submerging it in water heated to around 203°F (95°C) for about 90 minutes. Because water can’t exceed 212°F (100°C) at sea level, you’re limited to lower temperatures, which means longer processing times to achieve full conversion.
The tradeoff is worth it for many people. Temperature precision means less risk of degradation, and the sealed bag contains virtually all of the smell, which is a significant advantage if odor is a concern.
Natural Decarboxylation Without Heat
Some decarboxylation happens on its own during drying and curing, just much more slowly. Research comparing freshly harvested cannabis with air-dried flower found measurable conversion even without any added heat or light. In fresh cannabis, the ratio of CBD to CBDA was roughly 1:99. After standard air drying, that shifted to about 1:20, and CBD content increased fivefold over just 15 days of storage.
This natural conversion is real but incomplete. Air drying reduced the acid cannabinoid content by only about 1 to 2.5 percentage points depending on the compound. You’d need extremely long storage times to approach the conversion levels that 30 to 60 minutes of heat provides, and you’d lose potency to general degradation in the process. Long-term storage at room temperature steadily converts THC to CBN: one study found only 63.8% of THC remained after 12 months at 25°C. Freezing essentially stops this degradation.