THC lab results are reported on a document called a Certificate of Analysis, or COA. It lists the potency, safety screenings, and product details for a specific batch of cannabis. Once you know what each section means, you can quickly tell whether a product is as strong as advertised and whether it passed safety testing for contaminants like pesticides, mold, and heavy metals.
Start With the Header Information
Before looking at any numbers, check the top of the COA. A valid report includes the lab’s name and license number, the client (brand or grower), a batch or lot number, the dates the sample was collected and tested, and the sample type (flower, concentrate, edible, etc.). These details let you verify that the results actually match the product in your hand. If the batch number on your packaging doesn’t match the COA, or if the lab name and license are missing, treat the results with skepticism.
Look for a mention of ISO 17025 accreditation on the lab’s report or website. This is an international standard that requires labs to demonstrate their testing methods produce consistent, reproducible results. It doesn’t cover every test the lab runs, only the specific methods listed under its accreditation scope, but it’s the strongest signal that a lab’s numbers are reliable.
Understanding the Potency Section
The potency panel is what most people look at first. It lists cannabinoids, primarily THC and CBD, as percentages of total weight for flower or as milligrams per unit for edibles. You’ll typically see three lines that matter most: THCA, delta-9 THC, and total THC.
THCA is the raw, non-intoxicating form of THC found in the plant. It converts to delta-9 THC (the compound that gets you high) when heated, whether by smoking, vaping, or baking. But the conversion isn’t perfect. About 12.3% of the weight is lost as a carbon dioxide molecule drops off during heating. That’s why labs use a standard formula:
Total THC = (THCA × 0.877) + delta-9 THC
So if your flower tests at 25% THCA and 1% delta-9 THC, the total THC is (25 × 0.877) + 1 = roughly 22.9%. This “total THC” number is the one to compare across products. For edibles, the THCA has usually already been converted during manufacturing, so the milligram number listed is closer to what you’ll actually consume.
The same panel often includes CBD, CBN, CBG, and other minor cannabinoids. These follow the same percentage or milligram format. If you’re specifically looking for CBD-dominant products, check the total CBD line the same way: Total CBD = (CBDA × 0.877) + CBD.
Terpene Profile
Terpenes are the aromatic compounds that give cannabis its smell and flavor. A COA’s terpene section lists individual terpenes by name (myrcene, limonene, linalool, etc.) with their concentration as a percentage of total weight. Most products highlight the top three terpenes by concentration. In vape oils, any terpene added during manufacturing that makes up 0.2% or more of the final product’s volume should be listed separately.
Total terpene content for flower typically falls between 1% and 5%. Individual terpenes above 1% are considered high. This section is largely about flavor and aroma preference, so there’s no pass/fail here. It helps you predict what the product will taste and smell like, and some consumers use it to choose products based on the effects associated with specific terpene combinations.
Pesticide Screening
The pesticide panel tests for dozens of chemical residues and is strictly pass/fail. Each pesticide has a maximum allowable concentration measured in parts per million (ppm). Most thresholds sit at 0.2 ppm, with a few compounds allowed up to 0.4 or 0.5 ppm. If any single pesticide exceeds its limit, the entire batch fails and cannot legally be sold. There is no remediation option for a pesticide failure in most states: the product must be destroyed.
On your COA, you’ll see a long list of pesticide names with either a numerical result (in ppm) or simply “Pass” next to each one. Some labs list “ND” (not detected), meaning the pesticide was below the instrument’s detection limit. That’s the best result. If the report shows a blanket “Pass” at the top of the pesticide section, it means every compound on the panel came in under its respective threshold.
Microbial Contaminants
This section screens for bacteria, yeast, and mold. Results are reported in colony forming units per gram (CFU/g), which is a measure of how many living microorganisms are present. For flower and processed products, typical limits look like this:
- Total aerobic bacteria: must be under 100,000 CFU/g
- Total yeast and mold: must be under 10,000 CFU/g
- E. coli: must be under 1 CFU/g (essentially none)
- Salmonella: must not be detected at all
Edibles are held to even stricter standards. Both Salmonella and certain dangerous strains of E. coli must come back as “None Detected.” If you’re immunocompromised or particularly concerned about safety, this is one of the most important sections on the entire report.
Heavy Metals
Cannabis plants absorb metals from soil and water, so every COA should screen for at least four: arsenic, cadmium, lead, and mercury. Results are listed in parts per million (ppm), and each metal has a maximum action level set by the state. These limits vary by jurisdiction and by product type (inhalable products generally have stricter limits than edibles because the lungs absorb metals more efficiently than the gut).
Like pesticides, heavy metals are essentially pass/fail. You want to see “Pass” or results well below the listed action levels. “ND” (not detected) is ideal. Even trace amounts within legal limits are considered safe for the consumption method the product is designed for.
Residual Solvents
This section only applies to extracts and concentrates made using chemical solvents like butane, propane, or ethanol. It does not appear on flower COAs. The results show how much solvent remains in the final product, measured in ppm. Health Canada, for example, sets the limit for butane, ethanol, and propane in cannabis oil at 5,000 ppm each. U.S. state limits vary but follow similar logic: small residual amounts are acceptable, while high levels indicate poor manufacturing and could irritate your lungs or cause other health effects.
If you’re buying solventless products like rosin or bubble hash, this panel should either be absent or show “ND” across the board, since no chemical solvents are used in production.
Moisture and Water Activity
Moisture content and water activity (abbreviated aw) tell you how well the flower was dried and how likely it is to develop mold during storage. These are different measurements. Moisture content is the percentage of water by weight. Water activity measures how available that water is for microbial growth, on a scale from 0 to 1.
The industry standard, established by ASTM International, puts the ideal water activity range for dried cannabis flower at 0.55 to 0.65 aw. At this level, the flower is shelf-stable and won’t support the growth of bacteria, mold, or yeast. Mold and yeast begin growing at 0.70 aw, so anything at or above that number is a red flag. Flower that’s too dry (below 0.55 aw) won’t grow mold but may have degraded terpenes and a harsh, brittle texture.
What “ND,” “LOQ,” and “
You’ll see these abbreviations scattered throughout every COA. “ND” stands for “not detected,” meaning the substance wasn’t found at any measurable level. “LOQ” is the limit of quantitation, the smallest amount the lab’s equipment can reliably measure. “
Some labs also list “LOD” (limit of detection), which is even lower than LOQ. A result between LOD and LOQ means the compound is technically present in trace amounts but too small to assign a reliable number to. In practice, you can treat ND,
You’ll see these abbreviations scattered throughout every COA. “ND” stands for “not detected,” meaning the substance wasn’t found at any measurable level. “LOQ” is the limit of quantitation, the smallest amount the lab’s equipment can reliably measure. “ Some labs also list “LOD” (limit of detection), which is even lower than LOQ. A result between LOD and LOQ means the compound is technically present in trace amounts but too small to assign a reliable number to. In practice, you can treat ND,