Measuring milligrams in homemade edibles comes down to a simple formula: multiply the weight of your cannabis (in grams) by its THC percentage, apply a conversion factor, account for extraction loss, then divide by the number of servings. The math itself is straightforward, but each step introduces variables that can shift your final number, so understanding where imprecision creeps in matters just as much as the formula.
The Core Formula
Every edible dosage calculation starts with the same basic equation:
Total THC (mg) = Weight of cannabis (g) × THC percentage × 10
The “× 10” converts the result from grams to milligrams. So if you’re using 7 grams of flower labeled at 20% THC, the math looks like this: 7 × 0.20 × 1,000 = 1,400 mg of total THC in the raw material. (Multiplying grams by percentage as a decimal, then by 1,000, gives the same result as the shortcut above.)
But there’s a catch. The THC percentage on a label usually reflects “total THC,” which combines the small amount of active THC already present with the much larger amount of THCA, the inactive precursor that converts to THC when heated. The standard formula labs use is: Total THC = (THCA × 0.877) + THC. The 0.877 factor accounts for the molecular weight lost when THCA sheds a carbon dioxide molecule during heating. If your label already lists “total THC” as a single number, that conversion is baked in. If it lists THCA and THC separately, you need to apply the 0.877 multiplier to the THCA value before adding the two together.
Why Your Starting Number Is Already an Estimate
Even lab-tested flower isn’t perfectly uniform. Research published in Scientific Reports found that THC potency within a single cultivar batch varied by 3% to nearly 7% of the actual content, depending on where on the plant the sample was taken and which individual plant was tested. The top of a plant and the bottom can differ by 5 to 6 percentage points of actual THC. Between plants of the same strain grown in the same conditions, average THC varied by about 2.8%.
What this means in practice: if your flower is labeled at 20% THC, the bud you’re actually grinding might be anywhere from roughly 18.5% to 21.5%. That’s a meaningful swing when multiplied across several grams. Treat the label number as your best available estimate, not a precise measurement.
Accounting for Extraction Efficiency
When you infuse cannabis into butter or oil, not all the THC makes it into the fat. Some stays trapped in the plant material you strain out, and some degrades during heating. The percentage that successfully transfers depends on your method and your fat of choice:
- Cannabutter: 70 to 80% extraction efficiency with good technique
- Coconut oil: 80 to 85%, among the highest of any kitchen method
- Olive oil: 75 to 80%
Sous vide methods or carefully controlled low temperatures can push efficiency into the 80 to 90% range. A standard stovetop infusion with consistent stirring and proper timing lands around 70 to 80%.
To apply this to your calculation, multiply your total THC by the extraction rate as a decimal. Using the earlier example of 1,400 mg of total THC infused into coconut oil at 80% efficiency: 1,400 × 0.80 = 1,120 mg of THC in your finished oil.
Calculating Milligrams per Serving
Once you know the total THC in your infused fat, dividing by the number of servings gives you the dose per piece. If that 1,120 mg of infused coconut oil goes into a brownie recipe that yields 20 brownies, each brownie contains roughly 56 mg of THC. That’s a very strong dose for most people.
Here’s a full worked example targeting a more moderate 10 mg per serving:
Say you want each of 12 cookies to contain 10 mg. That means your batch needs 120 mg total. Working backward: if you’re using cannabutter at 75% efficiency, you need 120 ÷ 0.75 = 160 mg of THC in your starting flower. At 20% THC, that’s 160 ÷ 200 = 0.8 grams of flower. Less than a gram for the whole batch.
This is where many home bakers overshoot. A little cannabis goes a long way in edibles, and starting with too much flower is the most common source of unexpectedly powerful results.
Working With Concentrates
Distillate syringes and RSO (Rick Simpson Oil) simplify the math considerably because they’re already activated, meaning you skip the decarboxylation step and don’t lose THC to extraction. A typical RSO syringe holds 1 ml (about 1 gram) and contains 60 to 80% THC, so one full syringe delivers roughly 600 to 800 mg.
To dose with a syringe, you measure by volume. A rice-grain-sized amount is approximately 0.03 ml, which works out to about 18 to 24 mg of THC. If your syringe has measurement markings, you can calculate precisely: multiply the volume in milliliters by the stated THC percentage, then by 1,000 to convert to milligrams. For a 70% THC syringe, 0.1 ml gives you 70 mg.
Because concentrates are so potent, a digital scale that reads to 0.01 grams (a centigram scale) is helpful. For very small amounts, a milligram scale (0.001 g) provides even more precision, though these are harder to keep calibrated at home.
Tools That Improve Accuracy
A digital kitchen scale is the single most useful tool for edible dosing. Measuring cannabis by volume (teaspoons, tablespoons) is wildly inconsistent because density varies with grind size and moisture content. Weighing in grams removes that guesswork. For flower, a scale accurate to 0.1 grams is sufficient. For concentrates, look for 0.01 gram precision.
Even distribution matters as much as total calculation. If your infused butter isn’t mixed thoroughly into the batter, some servings will be significantly stronger than others. Blend your infused fat into the recipe as completely as possible, and consider recipes where the fat is evenly incorporated (like gummies made from infused oil) rather than ones with uneven texture (like chunky cookies).
Some home cooks use infusion-testing devices that estimate THC concentration in finished butter or oil. These can give you a ballpark, but they lack the precision of professional lab equipment, which uses methods like high-performance liquid chromatography to quantify cannabinoids down to 1 mg per gram. If you want a truly verified number, some states allow consumers to submit samples to licensed labs for potency testing.
Dose Ranges and What They Feel Like
Knowing your milligrams only helps if you understand what those numbers mean in your body. General dose ranges for THC edibles:
- 1 to 2.5 mg (microdose): Mild symptom relief without noticeable intoxication. Good for first-timers or anyone wanting functional, subtle effects.
- 3 to 5 mg (low): Stronger relief, mild euphoria, possible changes in coordination and perception. This is a common recreational starting point, and 5 mg is enough to produce noticeable intoxication in many people.
- 10 to 15 mg (moderate): Effective for pain and nausea, but impairs coordination. Suited to experienced users. This is the standard single-serving cap for commercially sold edible pieces in most regulated markets.
- 20 to 30 mg (high): Strong euphoria and significant impairment. Only appropriate for people with established tolerance.
- 50 to 100 mg (very high): Likely to cause side effects like nausea, anxiety, and rapid heart rate in anyone without substantial tolerance.
Why Edibles Hit Differently Than Smoking
Your calculation tells you what’s in the food, but your body processes edible THC differently than inhaled THC. When you eat THC, your liver converts it into a metabolite called 11-hydroxy-THC, which crosses into the brain more readily and produces stronger, longer-lasting effects. The ratio of this metabolite to regular THC is significantly higher after oral consumption than after smoking. That’s why 10 mg eaten can feel more intense than 10 mg inhaled.
Oral bioavailability of THC is only about 6 to 10%, meaning most of the THC you swallow never reaches your bloodstream. But the portion that does get converted into that more potent metabolite, which is why edibles feel disproportionately strong relative to the amount absorbed. Peak effects take 1 to 2 hours, sometimes longer depending on stomach contents, so the most practical advice is to wait a full two hours before deciding your dose was too low.
Given all the variables involved, from flower variability to extraction efficiency to individual metabolism, treat your calculated milligrams as a well-informed estimate rather than a lab-grade measurement. Starting low and adjusting upward across separate sessions is the most reliable way to find your target dose at home.