Cannabis Vape Juice Potency Guide: THC Percent to MG

How strong is cannabis vape juice?

Most lab-tested cannabis vape cartridges in the US fall between 60% and 90% THC by weight. A 1-gram cartridge at 80% THC holds about 800 mg of THC. By comparison, 1 gram of flower at 20% THC holds about 200 mg. Vape oil is concentrated, so small puffs deliver meaningful amounts. Potency appears on legal packaging as THC percentage and, on tested products, as total THC in milligrams.

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THC percentage vs milligrams

Percentage shows concentration. Milligrams show the total THC in the package. Use the net weight, not the cart size printed on the box.

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1. Find the net weight in grams on the label.
2. Convert grams to milligrams: 1 gram equals 1,000 mg.
3. Turn the THC percentage into a decimal: 80% becomes 0.80.
4. Multiply net weight in mg by the decimal.
5. Record the result as total THC in the container.

• 0.5 g at 70% THC: 500 mg x 0.70 = 350 mg THC
• 1 g at 85% THC: 1,000 mg x 0.85 = 850 mg THC
• 1 g at 60% THC: 1,000 mg x 0.60 = 600 mg THC

How to dose a cannabis vape

Puff size varies by device, battery setting, and draw length, so treat every new cartridge as unknown until you test it.

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1. Start with one short puff of 1 to 3 seconds.
2. Wait at least 10 to 15 minutes before judging the effect.
3. Note the draw length and battery setting if the effect feels right.
4. Take a smaller second puff only if needed.
5. Keep the same routine for that product before changing dose.

Inhaled THC reaches the bloodstream fast, so the wait matters more than with edibles. A single puff may deliver roughly 1 to 5 mg THC depending on the cartridge and device. That estimate is not a label claim.

Read the lab label before buying

• Total THC in mg and THC percentage
• Net weight in grams
• CBD and minor cannabinoid content
• Terpene profile if listed
• Batch or test number
• Packaging date and expiration date

In legal US states, retail cannabis products generally require potency testing and labeling. Buy from licensed shops that show batch-specific results. Unlabeled vape oil gives you no reliable way to estimate dose.

Tolerance and potency drift

Regular vape use raises tolerance, which can make a cartridge feel weaker over time. Potency also drifts with heat, light, and air. Store cartridges upright, capped, in a cool dark place. Do not leave them in a hot car. Keep the package label so you can compare batches. This guide is informational and is not medical advice.