How a cannabis dosing calculator works
A cannabis dosing calculator converts your raw product into milligrams of THC per serving. You feed it three things: the weight of your material, the potency from the label or a lab test, and the number of servings you want. It multiplies weight by potency to get total THC, then divides by servings. That is the whole trick. Everything else is adjustment.
The Ultimate Guide to Using a Cannabis Dosing Calculator
Say you have 3.5 grams of flower testing at 20% THC. The calculator returns roughly 700 mg of THC in the jar. Decarboxylated and infused into a batch of 40 brownies, that is about 17.5 mg per piece, assuming perfect extraction. It never is perfect.
The formula underneath
For flower and concentrates, total THC = grams x 1000 x potency percentage. One gram at 20% equals 200 mg. One gram at 25% equals 250 mg.
If the label lists THCA separately, multiply THCA by 0.877 before adding it to THC. That 0.877 is the mass difference when the acid group drops off during decarboxylation. Labels in most legal states report both numbers for this reason.
- Weight in grams x 1000 = milligrams of material
- Milligrams x THC percentage = potential THC
- Potential THC x extraction efficiency (0.6 to 0.9 for most home infusions) = THC you actually get
- That number divided by servings = dose per serving
Most calculators skip the efficiency step. I would not. A butter or oil infusion typically pulls 60% to 80% of the available cannabinoids unless you use a solvent assisted method. Concentrate into oil runs higher.
Why the calculator's answer is a starting point, not a promise
Two people eat the same 10 mg gummy and have completely different afternoons. Body weight matters less than people assume. What matters more: liver enzyme activity (CYP2D6 and CYP3A4 in particular), how much food is in the stomach, tolerance from regular use, and whether you took any medication competing for the same enzymes.
Inhaled THC hits in minutes and fades in two to three hours. Swallowed THC has to pass through the gut and then the liver, which converts a chunk of it into 11-hydroxy-THC, a metabolite that crosses the blood brain barrier more readily. That is why edibles feel different and last longer.
The calculator has no field for any of this. Use it to avoid a 200 mg mistake, not to fine tune.
Standard serving sizes in the legal US market
Most regulated states settled on 10 mg THC as one serving, with 100 mg as the per package cap. Some products are scored into 5 mg or 2.5 mg pieces. Colorado helped pioneer the 10 mg standard and other states followed.
A reasonable ladder I see work:
- 2.5 mg, first timer, or anyone returning after a long break
- 5 mg, occasional user, standard low dose
- 10 mg, one full serving, regular user
- 15 to 25 mg, heavy tolerance only
Wait at least two hours before redosing an edible. The urge to take more at the 45 minute mark is the single most common way people end up having a bad night.
Flower, edibles, and concentrates need different inputs
Flower: potency runs 15% to 30% THC. If you are making your own oil or butter, decarboxylate first, oven at 240F for 30 to 40 minutes, or the calculator's math will overstate the result, sometimes badly. Raw flower contains mostly THCA, which is not psychoactive.
Concentrates: potency 60% to 90%. A gram of 80% shatter puts 800 mg of THC on the table. That is 80 servings at 10 mg. Small errors in measurement get big fast.
Commercial edibles: skip the math. Use the label. The stated per serving amount on a regulated product is more reliable than anything you will calculate at home.
When the label and the calculator disagree
They will, sometimes by 20% or more. Flower potency varies within a single plant, let alone a harvest. Lab results carry their own margin of error. Homemade infusions are inconsistent from batch to batch even with the same recipe and the same starting material.
What to do: keep a simple log. Note the product, the calculated dose, the time, and how you felt at the two hour mark. After four or five entries you will have a personal correction factor that beats any calculator.
Bottom line
A dosing calculator is arithmetic with a nicer interface. It is good for one job: keeping you from making a 50 mg edible by accident. The number it spits out is a hypothesis. Your response to it is the data.