What is considered high THC? There's no single agreed cutoff, but market data give useful benchmarks. Retail flower commonly tests around 20% THC, so flower in the mid-20s or above sits at the strong end of the shelf, while concentrates average around 70%. Here's how those percentages are measured, why labels show total THC, and how to choose a strength that fits you.
What a THC percentage means
A THC percentage is a share by weight. Flower labeled 20% THC contains about 200 mg of THC in every gram, so an eighth (3.5 grams) of it holds about 700 mg in total. Concentrates use the same math:
| Label THC | THC per gram | THC per eighth (3.5 g) |
|---|---|---|
| 15% flower | About 150 mg | About 525 mg |
| 20% flower | About 200 mg | About 700 mg |
| 25% flower | About 250 mg | About 875 mg |
| 70% concentrate | About 700 mg | Concentrates are usually sold by the gram or half gram |
Edibles, drinks and tinctures are labeled differently, in milligrams per serving, because what matters there is the dose you swallow. Either way, the number describes what's in the product, not how much your body absorbs. Inhaling delivers only part of the THC in the material, and how much depends on how you consume it.
Why flower and concentrates sit on different scales
Flower is mostly plant material, with its cannabinoids packed into tiny resin glands, so its THC share tops out in the tens of percent. Concentrates are made by pulling that resin away from the plant, which is why their THC share runs several times higher.
In a 2025 study, researchers bought 178 flower and 99 concentrate products from 52 Colorado dispensaries and tested them. Flower averaged about 21% THC, and the strongest sample came in at 33%. Concentrates averaged about 71%, topping out near 84%. Vape cartridges are filled with concentrate oil, so their numbers land in the concentrate range too.
Lab variation, and why numbers shift between batches
A THC number is a measurement, and measurements vary. Three things push a label away from what's in your jar:
- The plant itself: in a 2025 study of greenhouse-grown flower, total THC varied by about 3% to 7% of its value within the same part of plants in a batch. Between the tops and bottoms of plants, it varied by about 5% to 6%.
- The lab: an analysis of Washington State testing data found systematic differences in the results reported by different labs, even after accounting for other explanations. The authors noted that no universal standard for lab testing methods exists.
- The label: in the Colorado study, 96% of concentrates tested within 15% of their labeled THC, but only about 57% of flower did, and tested THC ran lower than labeled on average for both.
Michigan labels acknowledge this. Along with THC and CBD content, they must state that actual values may vary by 10%. Read a label as a good estimate, and don't sweat the difference between 26% and 28%. Our guide to reading a cannabis label walks through the rest of the package.
Total THC versus THCA: the 0.877 conversion
Raw flower holds most of its THC as THCA, an acid form that isn't intoxicating until heat converts it. When THCA turns into THC, it sheds a carboxyl group and gets lighter, so a gram of THCA can become at most about 0.877 grams of THC.
That's why labs report total THC with a standard formula:
Total THC = THC + (THCA × 0.877)
For example, flower that tests at 24% THCA and 1% THC has a total THC of about 22%: 24 times 0.877 is about 21, plus 1. If your label lists THCA and THC separately, total THC is the number that reflects strength once the flower is smoked or vaped. Labs calculate total CBD the same way, as CBD plus CBDA times 0.877. Our guide to THC vs. THCA explains the chemistry.
What is considered high THC for flower?
Potency has climbed over the decades. Federal researchers report that the THC potency of illegal cannabis seized by law enforcement quadrupled between 1995 and 2022, and researchers studying legal markets describe high-THC products as quickly gaining market share.
For today's legal flower, here's a rough guide based on the Colorado study's numbers:
| Label THC | Where it sits on today's shelves |
|---|---|
| Under 15% | Mild for today's market |
| 15% to 20% | Moderate |
| 20% to 25% | Around or above average |
| 25% to 30% | High |
| Over 30% | At the very top, so look closely at the lab report |
Is 30% THC high? Yes. In the Colorado study, no flower sample tested above 33%, even though some labels claimed as much as 39%. A very high number on a label deserves a second look at the lab report, and our list of high-THC strains shows which names tend to land at the top.
Concentrate ranges by type: shatter, wax, live resin, distillate and diamonds
Concentrates come in many textures, and the name mostly describes texture and method:
| Type | What it is |
|---|---|
| Shatter | A glassy, brittle extract, usually made with a hydrocarbon solvent such as butane |
| Wax and budder | Softer extracts whipped or stirred into an opaque, waxy texture |
| Live resin | An extract made from plants frozen right after harvest, to keep more of the fresh aroma |
| Distillate | A refined oil with most other plant compounds removed, common in vape cartridges |
| Diamonds | Crystals of THCA pulled out of the extract, often sold with a terpene-rich sauce |
As a group, concentrates averaged about 71% THC in the Colorado study. Refined products like distillate and THCA crystals are processed toward a single compound, so they tend to sit at the top of that range. For any specific product, the label is your starting point. Concentrates are used in tiny amounts; a first dab is often no bigger than a grain of rice. Our roundup of high-potency cannabis products compares the formats.
What else shapes intensity: terpenes, tolerance, method, freshness
The percentage tells only part of the story:
- Terpenes: these aroma compounds shape how a strain smells and tastes, and many people believe they color the experience, though research on that is still early.
- Tolerance: regular use builds tolerance, so the same product can feel very different to a daily user and an occasional one.
- Method: federal researchers note that dabbing can deliver large amounts of THC very quickly, which raises the risk of unpleasant side effects.
- Dose: one small puff of strong flower can be gentler than a whole joint of milder flower.
- Freshness: THC slowly breaks down as flower ages, so an old jar can test lower than its label.
- Setting: being tired, hungry, stressed or somewhere unfamiliar can make the same dose feel stronger.
Our guide to why cannabis can feel stronger digs into why the same product can feel different from one day to the next.
Choosing a THC level by experience
Higher THC isn't a sign of higher quality, and more isn't right for everyone. A few starting points:
- New, or back after a long break: choose flower around 15% THC or lower, take one small inhale, then give it 15 minutes or more before deciding on another.
- Occasional: moderate flower gives you room to adjust. Keep sessions small when you try something new.
- Experienced: stronger flower or concentrates may suit you, but a little concentrate goes a long way. Ask yourself whether the top number on the shelf is really what you want.
Research gives one more reason to think twice about chasing potency. A 2022 systematic review found that, compared with lower-potency cannabis, higher-potency products were associated with a greater risk of psychosis and cannabis use disorder. All of the included studies were observational, so they show a link rather than proof of cause; results for depression and anxiety were mixed.
Using high-THC products: what to expect, taking too much and the legal side
Expect faster, stronger effects than you'd get from the same amount of milder flower, especially with concentrates. Use smaller amounts, go slowly, and avoid mixing cannabis with alcohol.
Too much THC can bring anxiety, a racing heart, dizziness or nausea. If it happens, the feeling passes. Stop using, move somewhere calm, sip water and give it time. Don't drive: Michigan cannabis labels warn that driving while impaired by cannabis is against the law. For advice, call Poison Control at 1-800-222-1222, the number printed on Michigan cannabis labels, and call 911 for chest pain, trouble breathing, fainting or severe confusion. Our guide to coming down from a high has more tips.
On the legal side, Michigan stores can sell an adult no more than 2.5 ounces in one transaction, and no more than 15 grams of that as concentrate. Adult-use shopping is for adults 21 and older; please consume responsibly.
