Guide
THC flower percentages: what 20% on a label means
In brief. A percentage on a THC flower label is a share of the dried flower’s weight. It may describe THCA, delta-9 THC or total THC, and those are three different numbers. Total THC is the one that describes what you will smoke: total THC = delta-9 THC + (0.877 x THCA). Our flower is hemp THCA flower, so its THCA figure is large and its delta-9 figure is small.
Checked Oct. 4, 2026.
The three numbers on a lab report
| Line | What it measures |
|---|---|
| THCA | The acid the plant makes. It is not THC until heated |
| Delta-9 THC | THC already present in the raw flower |
| Total THC | The THC the flower can yield once heated: delta-9 THC + 0.877 x THCA |
The factor 0.877 is the share of a THCA molecule’s weight left once heat removes its carboxyl group. The federal hemp rule writes the formula out and requires results on a dry-weight basis (7 CFR 990.1). Heat does the conversion quickly: in a laboratory study THCA was almost gone after 6 minutes at 145°C (Wang and colleagues, 2016).
What “20%” works out to
| Label says | Total THC | Potential THC in 1 g | In a half pound (226.8 g) |
|---|---|---|---|
| Total THC 20% | 20.0% | about 200 mg | about 45 g |
| THCA 20%, delta-9 0.2% | 17.7% | about 177 mg | about 40 g |
| THCA 25%, delta-9 0.3% | 22.2% | about 222 mg | about 50 g |
These are amounts in the flower, not amounts a person takes in. Some is lost to burning and to smoke that is never inhaled. We make no claim about effects at any percentage.
Why label figures can run high
Results for the same flower can differ from one laboratory to the next, and a seller gains from the higher one. In a 2023 study of retail cannabis in Colorado, observed THC averaged 23% below the lowest figure on the label, and about 70% of samples fell more than 15% short (Schwabe and colleagues, PLOS ONE, 2023). Read the lab report for the lot, not the number on a banner, and be wary of figures far above the grade.
What the percentage means for the law
Today federal law counts only delta-9 THC, at 0.3% of dry weight, when it decides what is hemp (7 U.S.C. 1639o). From Dec. 11, 2026, it counts total THC (P.L. 119-37, sec. 781). Every row in the table above is far over 0.3% total THC, so flower like it becomes marijuana under federal law on that date, and we stop selling it. State law varies and some states ban THCA flower now; check yours before you order.
On our menu
Where we hold a Batch’s lab report, the product page shows its THCA % and total THC and links the file. Where we do not yet, we say so and send it on request. See the full list.
Sources
- 7 CFR 990.1 (definitions of total THC and decarboxylated)
- Wang and others, “Decarboxylation Study of Acidic Cannabinoids,” Cannabis and Cannabinoid Research, 2016. doi.org/10.1089/can.2016.0020
- Schwabe and others, “Uncomfortably high: Testing reveals inflated THC potency on retail Cannabis labels,” PLOS ONE, 2023. doi.org/10.1371/journal.pone.0282396
- 7 U.S.C. 1639o; P.L. 119-37, sec. 781
Questions
- What does 20% THC flower mean?
- That 20% of the dried flower's weight is THC once heated, if the figure is total THC. One gram then carries about 200 mg of potential THC. If the 20% is THCA, total THC is about 17.5%.
- How do you work out total THC from THCA?
- Total THC = delta-9 THC + (0.877 x THCA). The 0.877 is the weight THCA loses as it turns into THC. It is the formula in the federal hemp rule, 7 CFR 990.1.
- Is a higher percentage always better flower?
- Not by itself. The percentage measures one compound, labels can run high, and grade, freshness and the lab report for the lot matter as much. We make no effect claims for any figure.