This is a very complicated question. The strength of an edible depends on a great many variables: the recipe and what you are making, the strength/quality of the cannabis used, which part of the plant you are using, the amount of plant material used, method(s) of extraction, the recipes and its portion size, etc. Obviously this leaves room for lots of variation among these elements, so as you can probably guess there is no easy scale for potency when it comes to cannacooking. So how do you figure out how to dose your medical marijuana edibles? We decided to do some science and find out.

(Note: If you’re in a hurry, you can always skip the science and go directly to the results. That won’t make you a very good cannachef though, will it?)

An Example: Cannabutter

To illustrate just how varied the dosing of medical marijuana edibles can be, we collected data from various books (not many) and Internet sources (tons) regarding making cannabutter. Here’s the data we found, converted into ounces across the board, and then plotted in a pretty graph for your viewing enjoyment:

Please note that this graph only shows which ratios have been used — it says nothing about how often each ratio is used (its frequency). By far the most reported weed-to-butter ratio was a little over half a pound (2.5 sticks) of butter to a half ounce (14 grams) of cannabis — we aren’t sure why so many people chose to throw that extra half a stick of butter in! If you’re interested, here’s a breakdown of how many recipes in the data set used similar amounts:

(We specifically selected recipes and anecdotes that mentioned buds for a little more uniformity in our data, so keep in mind that these are recipes where people used buds. If they were using leaves or stems they would have to compensate for the lower amounts of THC contained in those parts of the plants.)

The Chemistry of THC

So we have a general idea as to how much weed most people use in their cannabutter recipes, but what does science tell us about how much plant matter to use? To answer the question properly, we must first examine the chemical properties of cannabis.

For starters, we know that the “main” active ingredient in cannabis, THC, is lipophilic. This means it prefers to dissolve in “oily” or “fatty” solvents rather than water. There are a number of oily solvents that THC will bind to, and for cannacooking purposes can be divided mostly into two groups:

  1. Alcohols – Ethanol/isopropanol alcohols are used in making hashes and tinctures
  2. Fats – Fatty ingredients are used to make things like cannabutter, cannacream, cannaoil, etc.

To understand why THC will dissolve in fats so well you must understand the concept of “polarity”: A molecule is “polar” when there is uneven electrical charge across it. “Non-polar” implies that the charge is basically equal across the molecule. The charge is caused by the electronegativity of the atoms in the molecule: depending on the atomic number of the constituent atoms and their electron shielding, some atoms exert a greater “pull” on the electrons of neighboring atoms. This means that the electrons spend more “time” near the more electronegative atom — creating, in essence, additional postive charge on the atom from whom the electrons were pulled (“time” here is used very loosely and is not the best descriptor but works well enough for our purposes). It is this unevenness of charge that causes a molecule to be considered “polar”, in so much that it has at least two “poles” — a side with positive charge and a side with an opposite negative charge (and if you sum the total charges of the molecule, it is zero).

The prime example of a polar molecule is H20 — water. The oxygen has high electronegativity compared to the hydrogens, so it “borrows” the electrons the majority of the “time”. This leaves a partial positive charge on the hydrogens, and a higher negative charge on the oxygen. Hence the molecule is polar! The electronegativity of oxygen, carbon, and hydrogen are 3.44, 2.55, and 2.2 respectively on the Pauling scale.

Now let us compare THC to water. THC is comprised primarily of carbon and hydrogen, which are of similar electronegativity (2.55 vs 2.2). It has a long carbon chain attached to a benzene ring, and this part of the molecule is almost entirey nonpolar. The charges are equalized. THC also has another couple of carbon rings with a few methyl groups, and these are essentially nonpolar as well. The only possible polarity arises from the charge imbalance caused by the electronegativity of the two oxygen atoms, and these are of very little significance compared to the size of the molecule. These two oxygen atoms, however, are what give THC its very limited water solubility.

Polar substances are miscible with water because they can form hydrogen bonds with the water molecules. The positive dipole of the polar molecule attracts a lone pair of electrons on water’s oxygen atom, and a hydrogen bond is formed. Nonpolar substances have (pretty much) equal charge across their surface, so they cannot dissolve in water.

THC dissolves in oil because of the van der Waals forces that exist between molecules. Basically, although the charge is “balanced” across a nonpolar molecule, electrons are delocalized and “random” and at some point uneven charge does occur on the atom, no matter how slight. This unevenness among like molecules affords a slight attraction between them, and causes oil to stick to oil. This force is much, much weaker than a hydrogen bond, to the point that oil and water just don’t mix.

So how do you get the most THC out of the plant matter?

There are two things to keep in mind. The first is that since THC is so lipophilic, simply by touching an appropriate solvent the transfer will occur naturally (albeit slowly). This is how tinctures are made (the plant matter is left in alcohol for long periods of time so that the THC is “absorbed” as the van der Waals forces do their thing). Since this process requires molecules to touch each other, it only makes sense that the more molecules in contact the faster this process will occur. The best way to accomplish this is by grinding your plant matter into as fine a powder as possible. Using a hand grinder works but picking up a coffee grinder is best. We like Krups, though any coffee grinder will work fine.

The second thing to consider is that THC has a boiling point of 392°F (200°C), so by heating up the plant matter you are forcing the THC out and into the surrounding material (e.g. butter). Other parts of the oil evaporate and boil as well, so here are some useful temperatures:

  1. At 70°F (21°C) the most volatile terpenoids start to evaporate, lending a pungent odor to the air. Mmmm.
  2. At 87°F (31°C) the less volatile terpenoids start to evaporate, lending the air even more pungent odors. Mmmmmmm.
  3. At 102°F (39°C ) virtually all of the terpenoids undergo evaporation fairly rapidly.
  4. At 122°F (50°C) Δ9-Tetrahydrocannabinolic acid decarboxylates (the water molecule held in the carbonate form evaporates) to make the psychoactive compound Δ9-Tetrahydrocannabinol. This step ensures you receive the maximum amount of THC is essential to almost all cooking recipes. At the very least, heat the marijuana to at least 122°F in the oven prior to use for maximum potency no matter what you plan on doing with it.
  5. At 150°F (66°C) Cannabidiol (CBD) melts and starts to evaporate.
  6. At 365°F (185°C) Cannibinol (CBN) boils.
  7. At 392°F (200°C) THC boils. This is usually your last chance to get clear vapor from a vaporizer. It’s also the hottest you need to get the plant matter to ensure quick release of the THC.

(Note: If you would like more specific information — including a precise break down of “active ingredients” — please see our guide to Cooking With Vaporized Marijuana. It has a handy break down of chemicals and their vaporization points.)

So we know that ~400°F is when we have most of the good stuff leaving the plant in the form of vapor (and hopefully attaching itself to something nice and fatty). This means that if you are cooking with a strain of cannabis like White Widow that has ~22% THC content, 28 grams of plant matter is releasing 6.6 grams of THC. Great, but what’s the most that can “get in” the butter once it’s released?

Solution, Solvents, and You

A solution is a homogeneous mixture. This means that the composition of the mixture is uniform throughout a sample of any size (in other words, it’s mixed up perfectly and hasn’t settled). The major component of the mixture is called the solvent, while the dissolved stuff is called the solute. Typically we are interested in the proportion, or concentration, of solute in the mixture. Since we know that 28 grams of cannabis containing ~22% THC leaves a maximum of about 6.6 grams of THC (the solute) behind after being cooked in butter (the solvent) and we know that one THC molecule binds to one fat molecule, we can use simple math to figure out how much material we would have to use to make a pound of butter with the maximum amount of THC in it. Simply divide the amount of THC (6.6 grams) into half the amount of butter (you are basically replacing half the butter with THC, so the 454 grams in 1 pound becomes 227 grams) to see how many “washes” it would take (35, in this case). Basically you would cook out the first 6.6 grams, strain out the used material, place fresh material in the butter and cook out that 6.6 grams, and repeat. By reusing the same butter with fresh marijuana you are raising the concentration of THC in the butter.

Now, keep in mind that you really won’t ever be able to get a completely even mix of THC and butter — that is just an ideal hypothetical. While cannabutter is the most common form of marijuana edible (mostly because it can be easily made and used in thousands of recipes), it isn’t quite as efficient as other extraction methods like tinctures and oils (and as a complex organic compound has nowhere near the same affinity for THC that some chemicals like hexane have).

The Results

  1. Most people use about a half ounce of cannabis for every half pound of butter. Yes, this is the same as saying “an ounce of cannabis for every pound of butter” or “a quarter ounce of weed for every quarter pound of butter” — but it seems like most people make their cannabutter in half pound batches.
  2. THC molecules bind on a 1:1 basis. This means that by using multiple washes, you could hypothetically wind up with a 50/50 mix of solute and solvent, though this is largely unrealistic due to impurities in most food-based solvents.
  3. Pre-baking your cannabis at 122°F (50°C) decarboxylates it. This ensures you are getting the most “usable” THC possible by converting THCa into THC.
  4. It’s important to grind your marijuana before you do anything with it. Increasing the surface area helps get the chemical reactions over with faster, which means less time stirring your butter and more time medicating.

So now you know how much you cannabis can use when making edibles, but how much should you use? The North American Industrial Hemp Council hosts an interesting set of medical marijuana edible dosing guidelines developed by the Nova Institute. It is a long, somewhat technical read but well worth it as it contains tons of information regarding the physiological and mental effects of cannabis ingestion.

In the Future

This article is simply that: an article. The data was gathered loosely over a few hours worth of reading books and browsing the Internet and is by no means the result of a scientific survey — nor are we organic chemists by any means. We’d like to improve the science of this article, so if you have any suggestions or corrections, we’d love to hear them!