Cannabis Potency Guide: THC % and Dosing Explained

Potency tells you how much THC is in a product, not how the high will feel. A 28% flower and a 10 mg edible can land in very different places, and the percentage on the jar is only one input. The useful move is to read two numbers: THC percentage, and milligrams of THC per serving. Then match those to your tolerance and how you plan to consume.

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What THC percentage really measures

On flower and concentrates, the percentage is a measure of weight: how much of that material is THC. On edibles and drinks, it shows up as milligrams instead. Most states require testing labs to report total THC, which is delta-9 THC plus the THC that forms when THCA is heated. The conversion is THCA × 0.877, so a flower labeled 25% THCA and 1% THC reads closer to 23% total THC on the certificate of analysis.

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That number comes from a sample of one batch. Flower is plant material, so potency drifts from bud to bud, and it drops as the flower cures, dries out, and gets handled.

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How to read a potency label

• Total THC: the number that matters for dosing. Some labels show THCA and THC separately, which is why the total looks different from either figure.
• Mg per serving vs. mg per package: a 100 mg chocolate bar is not a 100 mg dose. Divide by the number of pieces.
• Batch or harvest date: older flower loses potency and taste. Freshness counts.
• Serving size: a "serving" might be half a gummy. Read the fine print.

Potency by product type

Flower in most dispensaries today tests somewhere between 15% and 30% THC. Vape cartridges run 60% to 90%. Concentrates like wax, shatter, and live rosin sit in the same range or higher. Edibles are dosed in milligrams, often 5 mg or 10 mg per piece, with 100 mg per package as the common cap in states that allow it. Tinctures and oils give you a dropper, so you can dial a dose down to 1 or 2 mg.

Here is the part that trips people up: a 90% vape does not deliver nine times the effect of 10% flower. Inhalation efficiency, how long you hold it, and how your body handles THC all change the outcome. And when you eat THC, your liver converts some of it into 11-hydroxy-THC, which is more potent and lasts longer. That is why 10 mg eaten can feel heavier than a few puffs of strong flower.

Matching potency to your tolerance

If you are new, or coming back after a long break, start under 10% THC flower, or a 2.5 mg to 5 mg edible. Take one or two puffs, wait 15 minutes, and see where you land. Regular users often settle into the 15% to 22% range for flower because it stays flavorful and manageable. Daily consumers and people using cannabis for pain or sleep may go higher, but tolerance builds fast, and chasing the number is a quick way to spend more for less effect.

The edibles math, again

1. Check total mg per package and mg per piece.
2. Cut the piece if you need a smaller dose. A 10 mg gummy splits into 5 mg halves, then 2.5 mg quarters.
3. Wait a full two hours before deciding it did nothing. Onset varies with what you ate and your metabolism.
4. Keep a note of what worked. A dose that is mild on Tuesday can feel strong on an empty stomach Friday.

What the potency number leaves out

Terpenes, minor cannabinoids like CBG and CBN, and how the product was grown and cured all shape the experience. Two flowers at 20% THC can feel noticeably different. High-THC products also carry more risk: anxiety, racing heart, and paranoia show up more often at higher doses, and heavy daily use of concentrates is linked to dependence and withdrawal. Potency is a tool, not a scoreboard.

Quick reference by experience

• First-timer: 1 to 2 puffs of flower under 15%, or a 2.5 mg edible.
• Occasional: 10% to 18% flower, 5 mg edible, low-temp vape.
• Regular: 18% to 25% flower, 5 mg to 10 mg edible, 1 to 2 dabs.
• Heavy: 25%+ flower and concentrates, with planned tolerance breaks.

Buy from a shop that posts lab results, ask to see the certificate of analysis if you want it, and treat the label as a starting point rather than a promise.