How to Read a Cannabis Lab Report (COA)

A Certificate of Analysis (COA) is a formal test report issued by an independent analytical laboratory documenting the composition, potency, and safety profile of a specific batch of cannabis product. The term “batch” is critical — a COA is not a certification of a brand or a product line, but of a specific production lot identified by a unique batch or lot number. The same product reordered in a different batch will have a different COA with potentially different results.

COAs exist because cannabis operates entirely outside the federal Food and Drug Administration’s regulatory framework. Unlike pharmaceuticals, food, or dietary supplements, cannabis products cannot be reviewed, approved, or verified by the FDA. The federal Schedule I classification of cannabis means that no federal testing mandate, label accuracy standard, or safety review applies to cannabis products sold in state-licensed dispensaries. Third-party laboratory testing, mandated at the state level and documented in the COA, is the only systematic quality assurance mechanism available to cannabis consumers.

In all licensed US cannabis states, dispensaries are legally required to test every production batch through a state-licensed testing laboratory and to make the COA available to customers on request. Products that fail any mandatory testing panel cannot be legally transferred to a dispensary for retail sale. If you purchase cannabis from a licensed dispensary and the staff cannot provide a COA for a product, this is a compliance violation worth reporting to your state cannabis authority.

COAs are issued by independent, state-licensed cannabis testing laboratories. The key word is “independent” — the testing lab must be separate from and have no financial relationship with the cultivator, manufacturer, or dispensary whose product it is testing. This independence requirement is what gives the COA its credibility.

Beyond state licensing, the gold standard for analytical laboratory quality is ISO/IEC 17025 accreditation. This international standard, overseen by accreditation bodies such as A2LA (American Association for Laboratory Accreditation) and PJLA (Perry Johnson Laboratory Accreditation) in the United States, certifies that a laboratory has demonstrable technical competence, calibrated instrumentation, documented quality management systems, and has passed proficiency testing for the specific analytes it reports. ISO/IEC 17025 accreditation is not universal among state-licensed cannabis labs, but it is the mark of a lab operating to the highest analytical standards. Check the COA you are reading for the lab’s accreditation body and certificate number — you can verify this information on the accreditation body’s public database.

Most modern cannabis product packaging includes a QR code that links directly to the COA for that specific batch. Scanning this code with your smartphone’s camera will typically take you to the testing lab’s portal or the brand’s website, where the PDF COA is hosted. If no QR code is present, look for the batch or lot number printed on the packaging label and enter it directly on the testing lab’s website — most labs provide a public batch lookup tool.

You can also simply ask the budtender at the dispensary to pull up the COA on their point-of-sale system or provide a printed copy. In California and several other states, this is a legal right — dispensaries must make COAs available on request. If a dispensary is unable or unwilling to provide a COA for a product you are considering purchasing, that is a significant quality signal.

The cannabinoid panel is the most frequently referenced section of a COA. It lists the concentration of each measured cannabinoid as a percentage by weight (% w/w), typically for both the acidic (inactive) form and the neutral (active) form of each major cannabinoid.

The Total THC Calculation

This is the most important formula in cannabis consumer literacy:

The reason for this calculation is chemistry. Cannabis in its raw, unheated state contains predominantly THCA (tetrahydrocannabinolic acid), the acidic precursor to THC. THCA is not psychoactive. When the cannabis is heated — by smoking, vaporizing, cooking, or baking — it undergoes decarboxylation: the carboxyl group (-COOH) is removed as carbon dioxide (CO2). This process converts THCA to delta-9-THC, the psychoactive compound. The CO2 molecule that leaves the THCA has mass — specifically 12.3% of the original THCA mass. This means 1mg of THCA produces 0.877mg of THC after decarboxylation. Hence the multiplier.

A product labeled “28% THC” typically means the THCA content, when decarboxylated, would produce 28% Total THC. Some producers and labs report the raw THCA% prominently, which can mislead consumers into believing the potency is lower than it is. Always calculate or look for the explicitly stated Total THC figure. Similarly, Total CBD = CBD% + (CBDA% × 0.877).

Advertised vs Actual Potency

A significant body of research, including a widely-cited study in the Journal of Cannabis Research, has documented that many dispensary products have lower actual THC concentrations than their labels claim. One contributing factor is that some testing labs face commercial pressure to report high potency numbers (since products with higher THC sell better), creating an incentive structure that can compromise analytical integrity. This is one reason ISO/IEC 17025 accreditation and laboratory independence matter: they provide structural safeguards against this kind of result inflation.

As a practical guide: flower testing above 25% Total THC should be scrutinized carefully. Results above 30% are possible but uncommon. Results above 35% should be treated with significant skepticism unless the lab has an impeccable accreditation record and the specific cultivar is well-documented for extreme potency.

Minor Cannabinoids

A complete cannabinoid panel will also report minor cannabinoids including CBG (cannabigerol), CBN (cannabinol), CBC (cannabichromene), THCV (tetrahydrocannabivarin), and CBDV (cannabidivarin). These compounds are present in smaller concentrations but contribute to the overall effect profile through the entourage effect. CBN is associated with sedative properties and increases in aged or degraded cannabis (it forms from THC oxidation). THCV is associated with appetite suppression and energetic effects. Explore individual terpene profiles and cannabinoid guides for deeper analysis.

The terpene panel lists the aromatic and flavor compounds present in the cannabis sample, reported as percentages by weight. Terpenes are responsible for the characteristic smell and taste of different cannabis strains — myrcene’s earthy musk, limonene’s citrus, pinene’s pine, caryophyllene’s pepper — and are believed to modulate the psychoactive and therapeutic effects of THC and CBD through the entourage effect.

For a terpene to be perceptible to smell and to meaningfully influence the cannabis experience, a general threshold of approximately 0.1 to 0.5% is cited in the research literature. Products with a total terpene content above 2 to 3% are considered terpene-rich and typically represent higher-quality, more carefully processed flower or extract. Products with near-zero terpene content (such as highly purified distillates) may be potent but lack the complexity and potential synergistic benefits of full-terpene products.

The terpene panel is more commonly included in premium product COAs; some budget products or value flower may not have a comprehensive terpene report. When present, the dominant (highest-percentage) terpenes are often the most diagnostically useful for predicting the character of the experience. See our terpene library for profiles of all major cannabis terpenes.

The pesticide panel is, from a safety perspective, arguably the most important section of the COA. Cannabis cultivation, like any commercial agriculture, may involve pesticide application to control insects, fungi, and other pests. Many pesticides used in conventional agriculture are legal for food crops but are not approved for cannabis, either because of the inhalation exposure route (smoking introduces combustion byproducts of pesticides directly into the lungs) or because cannabis-specific safety data does not exist. State cannabis regulations establish lists of prohibited pesticides and action limits for permitted ones.

A typical pesticide panel screens for 60 to 70 distinct compounds. Results are reported as either ND (not detected, meaning below the limit of quantification of the instrument) or as a measured concentration in parts per million (ppm) or parts per billion (ppb). Each row has a state-mandated action limit; any detection above the action limit constitutes a failure.

Organochlorine pesticides — including myclobutanil, a common fungicide — are among the most problematic in cannabis because myclobutanil releases hydrogen cyanide gas when combusted at the temperatures reached during smoking. Some states have banned myclobutanil entirely for cannabis cultivation. Other high-concern pesticides include bifenthrin, imidacloprid, and spirotetramat.

For a pesticide panel to pass, every single compound screened must show ND or a result below its specific action limit. A single exceedance fails the entire batch. When reading a COA, scan the Pass/Fail column of the pesticide table first — any “Fail” entry in this table means the product should not have been legally sold.

Microbial contamination is a particular concern for immunocompromised cannabis patients, including those undergoing chemotherapy, living with HIV/AIDS, or taking immunosuppressive medications. Cannabis flower can harbor molds, bacteria, and fungal spores that are harmless to healthy individuals but can cause severe respiratory or systemic infections in vulnerable patients.

Standard microbial panels test for:

• Total Yeast and Mold Count (TYMC): The aggregate count of yeast and mold colony-forming units per gram (CFU/g). Typical action limits range from 10,000 to 100,000 CFU/g for flower, with stricter limits for inhaled concentrates.
• Total Aerobic Count (TAC) or Total Aerobic Bacteria (TAMC): Aggregate bacterial count. Limits vary by state and product type.
• Aspergillus species: Aspergillus fumigatus, A. flavus, A. niger, and A. terreus are specifically screened because these species can cause aspergillosis — a potentially fatal lung infection in immunocompromised individuals. Many states require detection of any Aspergillus to trigger a fail regardless of concentration.
• E. coli (shiga toxin-producing strains): Must be absent or below detection limit in all products.
• Salmonella: Must be absent in all products.

Microbial contamination is most likely in poorly dried or stored flower with moisture content above 15%, and in products exposed to unsanitary handling during processing. Properly cured flower at 10 to 14% moisture content is significantly less susceptible to mold growth. See moisture content in the section below.

Cannabis is a hyperaccumulator plant — it efficiently absorbs heavy metals from soil through its root system and concentrates them in plant tissue. This is a feature of the plant that has been researched for phytoremediation (using cannabis to clean contaminated soil), but it creates real safety concerns when the plant is grown in metal-contaminated soil or with contaminated water sources.

The four heavy metals universally regulated in cannabis testing are lead (Pb), arsenic (As), cadmium (Cd), and mercury (Hg). State action limits for these metals are typically aligned with USP (United States Pharmacopeia) standards. Importantly, concentrate products face stricter action limits than flower, because the extraction process concentrates everything in the plant material — including metal contaminants — into a much smaller volume. A concentrate with 5× the concentration of a flower product will carry 5× the metal content per gram consumed.

Cannabis grown with organic, regulated inputs in tested soil is significantly less likely to contain heavy metal contamination than conventionally grown product or product from unregulated cultivation. COA heavy metal results are reported in micrograms per gram (μg/g) or ppm, with action limits typically in the range of 0.1 to 0.5 μg/g for the most toxic metals.

Cannabis concentrates produced using hydrocarbon or alcohol extraction methods — including BHO (butane hash oil, producing shatter/wax), propane hash oil, hexane extracts, or ethanol extracts — may retain trace quantities of the extraction solvent in the final product if the purging and removal process is incomplete. Residual solvents are toxic at sufficient concentrations and their presence in an inhaled product is a health risk.

The residual solvent panel tests for butane, propane, hexane, ethanol, isopropanol, acetone, and other process solvents. Results must be below the state action limit or below the instrument detection limit (reported as ND). Solventless extracts — such as rosin (made with heat and pressure) and bubble hash (made with ice water and agitation) — will not have detectable solvent residues by definition, and some brands use a “solventless” COA category that simply confirms ND for all solvents. Distillate products, which undergo additional molecular distillation after solvent extraction, typically also show ND results for solvents when properly processed.

Moisture content, expressed as a percentage by weight, is included in the COA for flower and some other products. Optimal cannabis flower moisture content for both quality and safety is 10 to 14%. Below 8%, the flower is too dry: trichomes (resin glands) become brittle and break off, terpenes evaporate, and the smoke becomes harsh. Above 15%, the flower is too moist: it burns inconsistently, can develop mold, and is more likely to fail microbial testing. Consumers buying dispensary flower can use moisture content as a freshness proxy — a well-cured, recently harvested product should read in the 10 to 13% range.

Knowing what makes a COA suspicious is as important as knowing how to read a passing one. The following are concrete warning signs that warrant either requesting a new report or avoiding the product:

• COA older than 12 months. A COA dated more than a year ago does not reflect the current product batch and may not reflect the current state of the product if it has degraded, been stored poorly, or been repackaged.
• Missing mandatory panels. If a state requires pesticide testing and the COA shows no pesticide panel, this is either a compliance failure or a sign the product was not properly tested.
• No accreditation listed for the lab. A COA that does not identify the testing laboratory, its accreditation number, or accreditation body has no independent verification of analytical integrity.
• THC potency claim above 35%. While not impossible, this level of potency in flower is exceptional and should prompt you to look up the laboratory’s track record and check whether the accreditation is current.
• Total terpene content of 0% in flower. Real cannabis flower always contains some terpenes. A zero terpene reading suggests either a deficient testing panel, a highly aged or degraded product, or a sampling error.
• Batch number does not match packaging. Always cross-reference the batch number on the COA with the batch number printed on the product package. Mismatched batch numbers indicate the COA does not apply to the product you are holding.

• What Is a Cannabis Dispensary? How They Work, What to Expect
• Edibles vs Smoking: Effects, Duration & Bioavailability
• Cannabis Testing: How Products Are Tested Before Sale
• Cannabis Concentrates Guide: Shatter, Wax, Rosin & More
• Cannabis Terpene Library — 20+ Profiles
• THC Percentage Guide: What the Numbers Mean
• What Are Cannabinoids? THC, CBD, CBG & Beyond