# OH’s Law Of Cannabis Edible Potency

People have been asking me quite a bit lately “How the ^%#@! do I figure out the potency of home-made capsules or edibles?” So I thought I’d sit down (after one of my own capsules kicked in) and write it up once and for all.

Yes, the title is a play on “Ohm’s Law”, and just like Ohm’s Law, the real power is in knowing which form of the formula to use. So I’ve written up some examples. And even though I think I have a good handle on my ego, I still have enough of one that I’d like to get credit for working this out. So here you go, world.

G = grams of cannabis
P = potency in milligrams of THC
S = strength of cannabis in percent
N = number of servings

For the S factor, you simply read the strength off the label if it’s legit stuff from a dispensary. Otherwise, assume 20% for top shelf/fire buds, 10% to 15% for mids/reggie, and 5% for schwag/brickweed.

For concentrates, assume 30% for kief, 40% for hash, 60% for hash oil, 80% for shatter.

### What Potency Will My Edibles Be?

What potency will my edibles be if I start with G grams of S strength and I want N servings?

$P = \frac {10 (G * S)} N$

For instance, let’s say you have an eighth ounce of Really Good Weed that’s 20% THC and you want to make 16 brownies. How strong will each of them be?

An eighth ounce is 3.5 grams, so it’s

10 * (3.5 * 20) / 16 = 700 / 16 = 43.75 mg each

Notice that the amount of oil, butter, alcohol, or whatever you use has nothing to do with the calculation! So if you’re making enough cannabutter or canna-coconut oil for a batch of brownies, you use the amount your recipe calls for 16 brownies, and that’s all there is to it.

Also, if you’re trying to calculate CBD or any other cannabinoid, it’s the same formula, you just have to know what the percentage of CBD is, which is always given as a percentage by weight.

### How Many Servings Will I Get?

How many servings will I get if I start with G grams of S strength and I want P potency?

$N = \frac {10 (G * S)} P$

Example: You just bought a quarter ounce of mids and you’re looking to make some fairly light capsules with 5 milligrams of THC each. How many can you make? A quarter ounce is 7 grams, and we can estimate that “mids” are about 10% THC, so:

10 * (7 * 10) / 5 = 700 / 5 = 140

You’d end up with 140 capsules. Now, to figure out how much coconut oil you’d need, let’s say you’ll be using #00 capsules, which hold 0.95 ml each. 140 * 0.95 = 133 ml, or just about 9 tablespoons.

### How Many Grams of Cannabis Will I Need?

How many grams of cannabis will you need to make N servings of P potency, if the cannabis is S strength?

$G = \frac {N * P}{10S}$

Example: you want to make 24 brownies with a solid 75 mg THC in each, but all you have is schwag, leaf, whatever you call it. How much of this leaf are you going to have to stuff into your butter?

Let’s be generous and say leaf is 5% THC, so:

24 * 75 / 10 * 5 = 1800 / 50 = 36 grams, or enough to get you in real trouble in most places that are not cannabis friendly.

And, just to be complete:

$S = \frac {N * P}{10G}$

This form tells you “how strong of a strain do I need if I am starting with G grams and want N servings of P potency each?” Not generally useful or practical, but there you go.

### Credit Where Credit Is Due

I did edit some parts to better reflect a neutral tone, as this is a USA based article. - James