Cannabis Dosage Calculator
Estimate a conservative starting dose of cannabis (THC) based on your body weight, experience level, and product potency. Always start low and go slow.
For flower/concentrate enter % THC. For edibles enter mg/serving instead and set potency to 100.
Formula
Step 1 – Effective THC needed (mg):
Effective THC = 0.05 mg/kg × Body Weight (kg) × Tolerance Factor
Tolerance factors: Naïve = 1.0 · Low = 1.5 · Moderate = 2.5 · High = 4.0
Step 2 – Product dose required (mg THC from product):
Product THC dose = Effective THC ÷ Bioavailability
Bioavailability: Oral ≈ 10 % · Inhaled ≈ 30 % · Sublingual ≈ 20 %
Step 3 – Fraction of serving:
Fraction = Product THC dose ÷ (Serving size × Potency %)
Step 4 – Safety cap:
Effective THC is capped at: Naïve 2.5 mg · Low 5 mg · Moderate 10 mg · High 20 mg.
Assumptions & References
- Baseline of 0.05 mg THC/kg for naïve users is derived from clinical microdosing studies (Zuurman et al., 2008; MacCallum & Russo, 2018).
- Oral bioavailability of THC is highly variable (4–20 %); a midpoint of 10 % is used (Huestis, 2007).
- Inhaled bioavailability ranges 10–35 %; 30 % used for smoked/vaped (Grotenhermen, 2003).
- Sublingual bioavailability estimated at 20 % (MacCallum & Russo, 2018).
- Tolerance multipliers are qualitative estimates based on published tolerance literature; individual variation is large.
- This calculator addresses THC only; CBD, terpenes, and other cannabinoids are not modelled.
- This tool is for educational purposes only and does not constitute medical advice. Consult a healthcare professional before use, especially if pregnant, nursing, or taking medications.
- Cannabis laws vary by jurisdiction. Ensure use is legal in your location.