Every legal cannabis product in the United States is required to undergo third-party laboratory testing before it reaches a dispensary shelf. The results of that testing are documented in a Certificate of Analysis — a COA. Most consumers never look at it. The ones who do usually scan the THC number and ignore the rest. This is like reading a nutrition label and only looking at calories.
A COA contains a wealth of information about what is actually in the product you are consuming. It also contains clues about what might be wrong with it. Learning to read a COA does not require a chemistry degree. It requires knowing what each section means and what constitutes a red flag.
Cannabinoid Potency: Beyond the THC Number
The cannabinoid potency panel is the section most consumers focus on, and it is the section most likely to be misleading. Understanding why requires knowing the difference between THCA and THC.
Raw cannabis flower contains very little active THC. It contains THCA — tetrahydrocannabinolic acid — which converts to THC when heated (decarboxylation). A COA for flower will typically show a high THCA number and a low THC number. The “total THC” figure on the label is calculated using a formula: Total THC = (THCA × 0.877) + THC. The 0.877 multiplier accounts for the molecular weight lost during decarboxylation.
Use the interactive COA breakdown tool below to explore what every section of a cannabis Certificate of Analysis means — with real examples and red flags highlighted for each panel.
Watch for these red flags in the potency section: THC percentages above 35% for flower should be viewed with skepticism — independent retesting studies have found significant potency inflation at some labs. If the same cultivar tests at 18% at one lab and 32% at another, the problem is the testing, not the plant.
CBD products deserve special scrutiny. A COA for a “500mg CBD tincture” should show approximately 500mg of total CBD when you multiply the per-serving amount by the number of servings. If it shows 300mg, you are not getting what you paid for.
Terpene Profile: The Fingerprint
The terpene panel provides a detailed breakdown of individual terpene concentrations, usually reported in milligrams per gram or as a percentage. This section is the product’s aromatic and pharmacological fingerprint.
Total terpene content for quality flower typically ranges from 1% to 5%. Below 0.5% suggests the product has been over-dried, over-processed, or poorly stored. The ratio between the top three terpenes is more informative than any individual number — it predicts the subjective character of the experience better than THC percentage alone.
Pesticide Screening: The Safety Section
Every state-legal market requires pesticide testing, but the list of tested compounds and the allowable limits vary dramatically by state. A comprehensive pesticide panel tests for 60 to 100+ compounds, including myclobutanil (Eagle 20), which converts to hydrogen cyanide when heated — a genuine health hazard in combusted or vaporized products.
A “pass” on the pesticide panel means all tested compounds fell below the state’s action limits. It does not mean no pesticides were detected — it means levels were below the regulatory threshold. If the COA shows “ND” (not detected) for all pesticides, that is the cleanest possible result.
Residual Solvents: Concentrates and Edibles
If you are consuming concentrates produced via solvent extraction (BHO, CO2, ethanol), the residual solvent panel tells you how much extraction solvent remains in the final product. Common solvents tested include butane, propane, ethanol, isopropanol, and hexane.
State limits typically range from 500 to 5,000 parts per million depending on the solvent and state. Lower is better. Clean concentrates should show levels well below the action limit, ideally in the low hundreds of PPM or less.
Heavy Metals: The Silent Contaminant
Cannabis is a bioaccumulator — it pulls heavy metals from the soil with remarkable efficiency. The heavy metals panel tests for lead, arsenic, mercury, and cadmium. These elements are toxic at low concentrations and accumulate in the body over time.
Heavy metal contamination is more common in cannabis than most consumers realize. A 2023 study found detectable lead in over 15% of cannabis products tested across multiple states. Products grown in contaminated soil or irrigated with contaminated water are at highest risk.
Microbial Testing: Mold, Yeast, and Bacteria
The microbial panel tests for total yeast and mold count, total aerobic bacteria, bile-tolerant gram-negative bacteria, and specific pathogens like E. coli, Salmonella, and Aspergillus. This panel is particularly important for immunocompromised patients using medical cannabis.
“Total yeast and mold” counts above 10,000 colony-forming units per gram are a red flag even if the product technically passes state limits. For patients with compromised immune systems, some physicians recommend only products with counts below 1,000 CFU/g.
Moisture Content and Water Activity
Often overlooked, moisture content (typically 8-13% for properly cured flower) and water activity (should be below 0.65 aw) indicate whether the product was properly dried and cured — and whether it is at risk for mold growth during storage. Water activity above 0.65 creates conditions favorable for microbial growth regardless of what the microbial panel showed at the time of testing.
How to Actually Get a COA
Most dispensaries do not proactively display COAs. You may need to ask. Reputable brands include QR codes on packaging that link directly to the COA for that specific batch. If a brand makes it difficult to access their lab results, that tells you something.
Look for the batch number on the product packaging and verify that it matches the batch number on the COA. A COA from a different batch is irrelevant to the product in your hand. Also verify that the testing lab is ISO 17025 accredited — this is the international standard for testing laboratory competence.
The five minutes it takes to read a COA will tell you more about what you are consuming than any budtender recommendation or online review. In an industry where quality varies enormously and regulation varies by state, the COA is the closest thing to an objective truth about your product.