01 / Tools
THC calculator
Turn flower potency into milligrams: enter %THC and grams for total mg THC and mg per joint, or convert mg ↔ % by mass. Simple, factual cannabis maths. Informational only, 18+.
02 / Calculator
Potency & conversion
TOTAL THC IN 1 G
200 mg
≈ PER 0.5 G JOINT
100 mg
The maths: total mg = grams × 1000 × (%THC ÷ 100). A gram of 20% flower holds ~200 mg of THC. Note: smoking does not deliver all of that — combustion and sidestream loss mean actual inhaled dose is a fraction of the total. 18+, informational only.
03 / Good to know
mg by mass vs inhaled dose
The mg figure here is total THC by mass — how much is physically in the flower. It is not the dose you absorb: smoking loses a large share to combustion and sidestream smoke, and even vaporising is not 100%. Treat it as a potency reference, not a dosing instruction.
Shopping by potency? Browse THC flower and concentrates, each listed with its lab-verified %THC.
04 / Questions
THC maths FAQ
How much THC is in a gram of flower?
Total mg = grams × 1000 × (%THC ÷ 100). So one gram of 20% flower contains about 200 mg of THC by mass. Smoking never delivers all of that — combustion and sidestream smoke lose a large fraction.
How do I convert THC mg to a percentage?
Divide the milligrams of THC by the mass in milligrams (grams × 1000) and multiply by 100. For example, 200 mg of THC in 1 g (1000 mg) is 20% THC.
How much THC is in a joint?
Multiply the grams in the joint by the total-mg formula. A 0.5 g joint of 20% flower holds roughly 100 mg of THC by mass — again, actual inhaled dose is much lower.