How a cannabis calculator works?

The idea of this calculator came from Old Hippie's Website. Our calculator uses the very same concept as Ohm's Law — you might not remember it from physics class, but it's easy to understand with cannabis.

Consider the following:

G = grams of cannabis
P = potency in milligrams of THC per portion
S = strength of cannabis in percent
N = number of servings
E = cooking efficiency (80% — accounts for a ~20% loss during cooking)

G is literally the quantity of plant material you want to use — no mystery here. N is the number of servings of your recipe. For example, if you are making a space cake and you cut your cake into 4 pieces, N equals 4.

S is probably the most complicated to figure out. If you are in a state or country where cannabis is not decriminalized, a good rule of thumb would be: assume 20% strength for top-shelf frosty buds, 10%–15% for mids, and 5% for schwag/brick weed. For concentrates, assume 30% for kief, 40% for hash, 60% for hash oil, 80%–95% for shatter. If you live in a legalized state or country, you can simply ask your budtender or dispensary about the flower or concentrate strength.

Now you understand what G, S, N, and E are. You can use all four to calculate your edible's potency with the following equation:

P = 10 × G × S × E / N

Confused? Let's go step by step. Assume you have 2 grams of high-quality cannabis with 20% THC and you want to make 8 cookies. How strong will each one be?

G = 2 (grams)
S = 20 (% of THC)
N = 8 (portions)
E = 0.80 (80% cooking efficiency)
P = 10 × 2 × 20 × 0.80 / 8 = 40 mg each

Notice that the amount of oil or butter you use has nothing to do with the calculation! You use whatever your recipe calls for — that's all there is to it.

Why 80% cooking efficiency?

When you cook with cannabis at home, some THC is inevitably lost along the way. Two main steps eat into your total:

• Decarboxylation — heating raw cannabis converts THCA into active THC. Done right, this step is about 90% efficient; done too hot or too short, you lose more.
• Infusion — transferring THC from plant material into butter, oil, or another fat is never 100%. A typical home infusion captures roughly 80–90% of available THC.

Combined, these two steps mean you realistically extract around 75–85% of the theoretical maximum. We use 80% as a reasonable middle-ground estimate. This gives you a more accurate picture of what's actually in your food — not just the theoretical ceiling.

This equation also works for other cannabinoids. Instead of THC percentage for S, just use CBD percentage, and you get the CBD dosage per portion.

Fortunately, you don't need to do any of this math yourself — you can see it happening live in our calculator. Just input the quantity, strength, and portion number, and we do all the work for you.