One of the most common questions among medical cannabis users is how to determine the THC content of a homemade edible. THC levels can vary widely, so the content of your starting material is often unknown. Once your batch is baked, is it even possible to tell how many milligrams of THC are in each serving? Even commercial producers get it wrong sometimes.

It’s difficult to get a precise measurement if your plant matter hasn’t been lab-tested. That involves multiple rounds of complex analysis. Even if you don’t know the exact percentage of certain cannabinoids, you can get a pretty close estimate, all it takes is a simple formula.

First, choose your weapon: Brain or calculator?

How to Dose Homemade Edibles

To anyone mathematically challenged: An online calculator (like this one) can approximately determine the THC percentage for you. If you’d prefer to do the math, here’s how the formula works.

Start your estimate with an average THC percentage. According to this table, low-quality cannabis or trim can contain as little as 3 percent THC, while top-shelf strains can average 25 percent or more. Government guidelines put the national average quality at 10 percent.

We’ll assume yours is 10 (if you don’t have the exact number from lab testing) to demonstrate the equation using a round number. First, you multiply your THCA by 10 to get your mg/g of THCA

• 10% THCA x 10 = 100mg of THCA per gram of cannabis
• The conversion rate of THCA to THC is 0.877
• 100mg THCA x 0.877 = 87.7mg of THC per gram of cannabis

So, one gram of 10% cannabis contains 87.7 milligrams of THC as long as there was no THC in the cannabis to start with. If there was 0.2% THC in your cannabis before you decarboxylate then you must add that in as well.

• 0.2% THC x 10 = 2mg
• 2mg + 87.7mg = 89.7mg of THC per gram of cannabis

Next, you divide the amount of THC in your recipe by the number of servings it makes to get the per-serving dose. For example, suppose you make cannabutter with a cup of butter and a cup of average-quality ground cannabis (about 7 grams). Multiply 7 by 89.7 (7 x 89.7), and you have 627.9 milligrams of THC in the butter. If you used half the cup of butter to make 24 cookies, the batch would contain 313.95 milligrams of THC. Divide that by 24 (the number of servings), and you know each serving contains approximately 13 milligrams of THC.

More Tips on Making Your Own

There’s no single way to make impeccable edibles – only trial and error can determine the right potency for each person. However, the following dos and don’ts will help perfect your craft:

• Don’t throw in too much cannabis. Against popular belief that half an ounce of cannabis makes a cup of cannabutter, lipids in oils can only bind with so many cannabinoids. Anything extra is wasted. As in the example above, a 1:1 ratio of butter to cannabis will do.
• Do alter accordingly if your recipe doesn’t yield the right dose per serving. Cut stronger recipes with regular butter or oil, and add more THC to weaker ones with an oil or extract.
• Don’t forget to decarboxylate your cannabis before cooking with it – raw cannabis not only tastes bad, but renders your edibles ineffective. (If your response was “De-what?”, read this guide.)
• Do stir your batter like your life depends on it. This will ensure the cannabutter is evenly distributed and the right dose makes it into each serving.
• Don’t grind your cannabis into powder. If too fine, the cannabis in your butter will be difficult to strain and produces a strong, plant-like taste. Best to grind it coarsely using a hand grinder.
• Do try testing your cannabutter’s potency before baking it into a dish, rather than testing it retroactively per the formula above. Think of the formula in reverse. Take a little oil with food or drink, wait an hour, and see how you feel. The amount of oil that yields the desired effect represents a single dose, which you can multiply per serving of your batch.

To determine the amount of THC or CBD in each serving of whatever goodie you baked, and how many grams of cannabis to use when baking- checkout this helpful cannabutter dosing calculator.