Cannabis labels pack a lot of information into a small space, and most of it actually matters for choosing the right product. The key numbers to focus on are total THC and CBD percentages (for flower and vapes) or milligrams per serving (for edibles), the terpene profile, and the batch test results you can pull up through a QR code. Once you know what each section means, shopping gets far more predictable.
THC and CBD Percentages
The most prominent numbers on any cannabis label are the cannabinoid potencies, usually listed as percentages for flower and vape products or milligrams for edibles. But there’s a subtlety most people miss: what the label lists as “THCA” is not the same as “THC.” THCA is the raw, non-psychoactive form found in the plant. It only converts to THC when heated, whether by smoking, vaping, or baking. The conversion isn’t one-to-one because some molecular weight is lost in the process.
To find the actual potency you’ll experience, labels in regulated markets show a “Total THC” figure calculated with this formula: THCA × 0.877 + THC = Total THC. So if a flower label reads 25% THCA and 0.5% THC, the total potential THC is about 22.4%. Some labels do this math for you and print the total directly. Others list THCA and THC separately, leaving you to calculate. If you only see THCA, multiply by 0.877 for a quick estimate.
CBD works the same way. The raw plant contains CBDA, which converts to CBD with a 0.877 multiplier. Total CBD equals CBD plus 87.7% of the CBDA amount. Products marketed as “high CBD” or with specific THC-to-CBD ratios (like 1:1) use these total figures, so a 1:1 ratio means roughly equal amounts of total THC and total CBD after conversion.
Edible Dosing: Milligrams Per Serving
Edibles are labeled differently from flower. Instead of percentages, you’ll see milligrams of THC per serving and per package. In most regulated states, the standard limit is 10 mg THC per serving and 100 mg THC per package for adult-use products. Oregon is stricter at 50 mg per package, while medical products in some states go as high as 500 to 2,000 mg per package.
This distinction between “per serving” and “per package” is one of the most important things on any edible label. A chocolate bar with 100 mg total THC might contain 10 individual servings of 10 mg each. Eating the whole bar means consuming 10 times what’s considered a single dose. If you’re new to edibles, one serving (or even half of one) is the place to start, since the effects take 30 minutes to two hours to kick in and last significantly longer than inhaled cannabis.
Terpenes: Your Best Shopping Tool
Terpenes are aromatic compounds that give cannabis its smell and flavor. More labels now include terpene profiles, and they’re arguably more useful than strain names for predicting what you’ll enjoy. The most common terpenes you’ll encounter are myrcene (earthy, musky), limonene (citrus), pinene (pine), linalool (floral, lavender-like), and caryophyllene (peppery, spicy).
Think of terpene profiles as a flavor and aroma guide. If you buy a product you love, note its top two or three terpenes. Next time you shop, look for products with a similar profile. This is far more reliable than chasing strain names, which can vary wildly between growers. Don’t treat terpene listings as medical claims. They’re preference signals that help you repeat good experiences and avoid bad ones.
The QR Code and Certificate of Analysis
Most legal cannabis products include a QR code on the packaging that links to a Certificate of Analysis, or COA. This is the full lab report for your specific batch, and scanning it is the single best way to verify what you’re actually buying. A COA is produced by an independent, state-licensed laboratory, and every legal product is required to have one.
When you pull up a COA, look for these key sections:
- Cannabinoid potency: THC, CBD, and sometimes minor cannabinoids like CBG, CBN, and CBC, listed as percentages or milligrams depending on product type.
- Contaminant testing: Results for pesticides, heavy metals (lead, mercury), residual solvents, mold, bacteria, and foreign materials. Each category should show a clear “Pass” or “Fail” designation.
- Lot or batch number: A tracking code that should match the number printed on your product’s physical label. If these don’t match, you’re looking at the wrong report.
- Terpene profile: Some COAs include a detailed terpene breakdown with individual percentages.
Always confirm that the product name, batch number, and THC/CBD values on the COA match what’s printed on the package. If there’s a mismatch, that’s a red flag.
Harvest Date, Test Date, and Freshness
Many cannabis labels include a harvest date, a test date, or both. The harvest date tells you when the plant was cut down, similar to a “born on” date for beer. It gives you a rough sense of freshness, but it can’t tell you anything about how the product was cured or stored afterward. As a general guideline, flower harvested more than six months ago is past its prime. Cannabinoids and terpenes degrade over time, especially with exposure to light, heat, and air.
The test date tells you when the lab analyzed that batch. A large gap between the harvest date and the test date isn’t necessarily a problem (curing takes weeks), but a product sitting on a shelf for many months after testing may have lost some potency and flavor. If you only see one date, it’s usually the packaging or test date. When both are available, use the harvest date as your freshness benchmark.
Hemp vs. Cannabis: The 0.3% Line
If you’re shopping for CBD products or seeing cannabis-derived items sold online or in non-dispensary stores, understanding the legal threshold matters. Under the 2018 Farm Bill, hemp is defined as cannabis containing no more than 0.3% delta-9 THC on a dry-weight basis. Anything above that threshold is classified as marijuana under federal law. This is why CBD products derived from hemp can be sold widely, while higher-THC products are restricted to licensed dispensaries in legal states.
Products near this boundary, including some delta-8 and other alternative cannabinoid products, can be confusing. The label should clearly state the delta-9 THC content. If it’s at or below 0.3%, the product is legally hemp-derived regardless of what other cannabinoids it contains.
Residual Solvents on Concentrate Labels
Concentrates, vape cartridges, and extracts go through additional processing that flower doesn’t, and their labels reflect that. One thing to look for, especially on the COA, is residual solvent testing. Solvents like butane, ethanol, and CO2 are commonly used to extract cannabinoids from plant material, and trace amounts can remain in the final product.
Safety limits are measured in parts per million (ppm). Lower-risk solvents like ethanol and acetone are permitted at levels below 5,000 ppm. More toxic solvents like methanol have tighter limits (below 3,000 ppm), and the most dangerous compounds like benzene must stay below 2 ppm. In a regulated market, your COA should show that the product passed residual solvent testing. If you’re buying concentrates, this is one of the most important sections to check, since contaminants that are negligible in flower become concentrated during extraction.
Putting It All Together
When you pick up a cannabis product, read the label in this order. First, check the total THC and CBD to gauge potency. For edibles, note the milligrams per serving, not just per package. Second, look at the terpene profile if one is listed, and compare it to products you’ve enjoyed before. Third, check the harvest or packaging date for freshness. Finally, scan the QR code and pull up the COA to verify the numbers match and confirm the product passed all safety testing. A product that checks all of these boxes in a regulated market has been through a level of scrutiny that most consumer goods never face.