by Sarah Mann, MD
When it comes to home cannabis cooking, everyone wants to know how to dose the edibles. If there were a straightforward equation, it would be to take the %THC in the product multiplied by the weight of the product to get grams of THC. Then multiply by 100 to get milligrams of THC available. Take that number and divide by the number of servings to get the dose per serving. If only it were so simple…
Raw cannabis contains THCA, a cannabinoid with medicinal value but no psychotropic properties. The THCA must be decarboxylated to THC to activate it. Not all THCA is converted to THC, 88% is decarboxylated. The other 12%? That would be the carboxyl group that was dropped from the molecule. Some manufacturers report THCA on the label while others do the conversion and report the resulting THC. So if your manufacturer reported THCA, multiply your total milligrams of THC by 0.88 to get your new total milligrams THC.
It also matters what you are using to extract the THC. When it comes to pulling cannabinoids and terpenes from the plant, not all fats are created equal. Oil will pull 80%, butter 70% and vegetable glycerin 60%. There is very little information available about specific extraction rates. So now you need to take that new total milligrams of THC and multiply it by the appropriate extraction rate, 0.8 for oil, 0.7 for butter and 0.6 for vegetable glycerin. This is where math is going to start to fail since both the oil and the method of decarboxylation will matter. This will give you a rough estimate of the total milligrams of THC available.
From there you can take the rough estimate of the total milligrams of THC available and divide it by the number of teaspoons. But you probably measured your oil in cups. So take the number of cups and multiply it by 48, which is the number of teaspoons in a cup.
Given all of the variables, the only true way to determine edible dosing is by lab analysis. And even that is fraught with problems. But if you follow these guidelines and you can make some consistent and reliable home edibles.
- Always cut the cannabutter vertically. As the butter was solidifying, the cannabinoids were sinking. The heaviest ones sunk the furthest. This results in a top and bottom that have totally different compositions. If you make even, vertical cuts you will get the full spectrum.
- Always be precise with measuring. Don’t use the big kitchen spoon as a tablespoon. Go get the real ones. Fill them exactly.
- Portion exactly. Make uniform pats of butter with a ruler. Measure brownies. Weigh cookie doughs.
- Stir everything very well. Do not leave clumps or pockets of dry ingredients.
I have seen many sources that discuss a formula, but it will be greatly overestimating the dose. If there were a formula, it would be this:
- %THC (or THCA) x product weight in grams = grams THC (or THCA)
- Grams THC (or THCA) x 100 = total milligrams THC (or THCA)
- If you have been using THC skip this step. If you have been using THCA the total milligrams THCA x 0.88 = total milligrams THC
- If you are using
- Oil: total milligrams THC x 0.8 = estimated total milligrams THC
- Butter: total milligrams THC x 0.7 = estimated total milligrams THC
- Vegetable glycerin: total milligrams THC x 0.6 = estimated total milligrams THC
- Estimated total milligrams THC/volume of oil = total THC milligrams per cup or teaspoon
- Volume of oil can be in cups or teaspoons, depending on your recipe
- If it is cups, plug the number into the above equation
- If it is milligrams, divide by 48 and plug that number in
NOW you can calculate the dosage per serving.
- volume of oil in the recipe x total THC milligrams per cup or teaspoon = milligrams per recipe
- milligrams per recipe/# servings
…there you go…as simple dosage calculation.
You are cooking with Durban Poison with 22% THCA, and you have 5g flower. You are using 1 cup of oil.
- 0.2 x 5 g = 1 g THCA
- 1 g THCA x100 = 100 mg THCA
- 100 mg THCA x 0.88 = 88 mg THC
- 88 mg THC x 0.8 = 77.5 mg THC
- 77.5 mg THC/48 tsp = 1.6 mg/tsp THC
You then use half a cup oil to make a dozen cookies.
- 24 tsp x 1.6 mg/tsp = 38.7 mg/recipe
- 38.7 mg/recipe/12 cookies = 3.2 mg THC/cookie.
You are cooking with Durban Poison with 22% THCA, and you have 1 ounce flower. You are using 2 cups of oil. You plan on storing one cup and making Cannabis Infused Bacon Jam with the other cup.
- 0.2 x 28 g = 5.6 g THCA
- 5.6 g THCA x100 = 560 mg THCA
- 560 mg THCA x 0.88 = 492 mg THC
- 492 mg THC x 0.8 = 394.2 mg THC
- 392.4 mg THC/48 tsp = 8.2 mg/tsp THC
You then use 1 cup oil to make a Cannabis Infused Bacon Jam (Check out PotSmoker’s to the Galaxy for the recipe).
- 24 tsp x 1.6 mg/tsp = 38.7 mg/recipe
- 38.7 mg/recipe/20 servings = 1.9 mg THC/serving
You want to make that same Cannabis Infused Bacon Jam, but much stronger. You decide to switch to an RSO. You are cooking with RSO with 86% THC, and you have a 1g syringe. You are using 1 cup of oil.
- 0.86 x 1 g = 86 g THC
- 86 g THC x100 = 860 mg THC
- Step 3 is not necessary, since you are starting with THC.
- 860 mg THC x 0.8 = 688 mg THC/cup
- 688 mg THC/48 tsp = 14.3 mg/tsp THC
You then use the whole cup to make the Cannabis Infused Bacon Jam
- 1 cup x 688 mg/cup = 688 mg THC/recipe
- 688 mg/recipe/servings = 34.4 mg THC/serving.