To decarboxylate THCA, you heat cannabis to between 220°F and 250°F for 20 to 60 minutes, depending on the method. This converts the non-intoxicating THCA in raw cannabis into active THC by stripping away a carboxyl group, which escapes as carbon dioxide. The process is simple, but temperature control matters: too low and the conversion is incomplete, too high and you start destroying the THC you just created.
What Decarboxylation Actually Does
Raw cannabis contains very little THC. What it has in abundance is THCA, a larger molecule with a carboxylic acid group attached. When you apply heat, that acid group breaks off as CO2, leaving behind a smaller, lighter molecule: THC. This is why smoking or vaping works instantly. The flame or heating element decarboxylates the THCA on contact. But if you want to make edibles, tinctures, or infused oils, you need to do this step yourself before cooking.
Because you’re losing that carboxyl group as gas, the final product weighs less than what you started with. About 12.3% of THCA’s molecular weight disappears as CO2. This is why lab reports use a conversion factor of 0.877 to calculate total potential THC: multiply the THCA percentage by 0.877, then add any THC already present.
The Oven Method
This is the most common approach and requires nothing more than a baking sheet, parchment paper, and an oven. Grinding your cannabis first increases surface area and helps everything convert evenly, though breaking it into small pieces by hand works too.
Set your oven to 240°F and place the rack in the middle position. Spread the ground cannabis in a single layer on a parchment-lined baking sheet and bake for about 40 to 60 minutes. At 250°F, you can cut this to around 20 to 30 minutes. The lower, slower approach gives you more margin for error, which matters because home ovens can fluctuate by 20 degrees in either direction. An inexpensive oven thermometer is worth the investment if you plan to do this more than once.
You’ll know the process is working when the cannabis shifts from bright green to a muted, light golden brown. The texture becomes dry and crumbly, breaking apart easily between your fingers. If it turns dark brown or smells like it’s burning, your oven is running hot. Turn the temperature down immediately.
The Mason Jar Method
If smell is a concern, a sealed mason jar traps most of the odor. Preheat your oven to 250°F, place your cannabis in a mason jar, and screw the lid on tightly. Set the jar on the oven rack (not touching the heating element or walls) and bake for about 30 minutes. The cannabis should look brownish when finished. Use oven mitts when handling the jar and let it cool completely before opening. The glass will be dangerously hot, and opening it immediately also releases all the trapped terpene-rich vapor.
The Sous Vide Method
A sous vide circulator gives you the most precise temperature control of any home method. Set the water bath to 205°F and hold it there for one hour. The key detail here is your container choice: standard zip-lock bags begin to soften and can leak at temperatures above 190°F. Mason jars work reliably. Vacuum-sealed bags rated for sous vide cooking are another option, though the simpler water displacement method (submerging a zip-lock to push out air before sealing the corner) also works if you use bags rated for the temperature.
After the hour-long decarb, you can drop the water temperature to 185°F and add your fat or oil directly to the jar for a four-hour infusion in the same water bath, making this a convenient one-device method for edible preparation.
Temperature: The Most Important Variable
The ideal range for decarboxylation sits between 220°F and 250°F. Within that window, lower temperatures need more time (closer to 60 minutes at 220°F) while higher temperatures need less (around 20 minutes at 250°F). Going above 290°F risks a different problem entirely: THC begins to oxidize into CBN, a cannabinoid with sedative rather than intoxicating effects. This degradation accelerates with both increasing temperature and prolonged exposure to air.
Terpenes are even more fragile. Beta-caryophyllene starts evaporating at just 246°F, which sits right in the middle of the typical decarb range. Myrcene and limonene hold on until around 330°F and 350°F respectively, but some terpenes begin degrading at temperatures as low as 100°F. If preserving the flavor and aroma profile matters to you, staying at the lower end of the decarb range (around 220°F to 240°F for a longer duration) will retain more of those compounds. For edibles where terpene preservation is less critical, 250°F for 20 to 30 minutes prioritizes speed and THC yield.
Decarboxylating Concentrates
Hash, kief, and other concentrates decarboxylate the same way but require closer attention because they’re denser and more potent. Place the concentrate in an oven-safe dish (a small glass ramekin works well) at 250°F. Concentrates will melt and begin to bubble as CO2 escapes. The process is complete when the bubbling slows dramatically or stops. This typically takes 20 to 30 minutes but varies with the thickness and type of concentrate. Watch for the bubble activity rather than relying on a timer alone.
Common Mistakes
The most frequent error is running the oven too hot. Because oven dials are approximate, the actual internal temperature may be 10 to 20 degrees above or below what you set. A thermometer eliminates the guesswork. The second most common mistake is skipping the step entirely when making edibles, resulting in a product with minimal psychoactive effect since raw THCA does not produce a high when eaten.
Overcrowding the baking sheet also causes uneven results. Cannabis piled in thick layers means the material on top heats differently from the material on the bottom. A single, even layer with some space between pieces gives consistent conversion. Finally, opening the oven frequently drops the temperature by 25 degrees or more each time, extending the process unpredictably. Set a timer and resist checking until it goes off.