How to Read a Cannabis COA

A Certificate of Analysis (COA) is an official laboratory report issued by an independent, state-licensed testing facility documenting the chemical composition and safety profile of a specific batch of cannabis product. The COA is the foundational transparency document of the legal cannabis market — the mechanism through which the regulatory promise that licensed products are tested, safe, and accurately labeled is made verifiable by consumers and regulators alike.

Every regulated cannabis product sold in a licensed dispensary in the United States must have an associated COA demonstrating it passed required state testing standards before it was placed on sale. This is not voluntary. State cannabis regulatory agencies license testing laboratories, set standards for testing methodologies and action limits, and require that COAs accompany all cannabis inventory from the point of testing through the point of sale. The seed-to-sale traceability systems (most commonly Metrc) that most states use create a digital chain connecting every product on a dispensary shelf to its COA in a government-accessible database.

The practical purpose of the COA for consumers is threefold: it verifies that the potency claims on the label are based on actual analysis (not estimated or invented); it confirms that the product passed safety testing for contaminants that can cause harm if present above threshold levels; and it provides the detailed chemical profile — terpenes, minor cannabinoids — that allows informed product selection beyond the headline THC number. A dispensary that cannot produce a COA for a product it is selling is operating outside compliance standards and should be reported to the state cannabis regulatory authority.

What ISO 17025 Accreditation Means

ISO 17025 is the international standard for the competence of testing and calibration laboratories. It requires that laboratories demonstrate: technical competence of staff; use of validated test methods; proper equipment calibration and maintenance; sample traceability; documented quality management systems; and participation in proficiency testing programs. A cannabis testing lab holding ISO 17025 accreditation has been independently assessed against these standards by an accreditation body.

Most legal states require cannabis testing labs to hold ISO 17025 accreditation or equivalent state-level accreditation as a condition of their testing license. ORELAP (Oregon Environmental Laboratory Accreditation Program) and A2LA (American Association for Laboratory Accreditation) are the primary accrediting bodies for cannabis labs in the US. When evaluating a COA, confirming that the issuing lab holds ISO 17025 accreditation provides assurance that the analytical methods used meet internationally validated standards.

The product identification header at the top of a COA establishes the traceability chain that makes the document legally meaningful. Every field in the header must match the physical product you hold for the COA to be valid for that product.

• Batch / Lot Number: The unique identifier assigned to this specific production batch. Must match the batch/lot number printed on the product packaging exactly, including any prefix letters, hyphens, and leading zeros. Any discrepancy means the COA is not for that product.
• Sample Name / Product Name: Identifies the product type and (for flower) usually the cultivar name. Verify this matches the product you are reviewing.
• Harvest / Production Date: Establishes when the product was created. Important context for interpreting terpene data — terpenes degrade over time, so a harvest date more than 6 months ago should prompt questions about how the product has been stored.
• Test Date / Report Date: When the laboratory conducted its analysis. Products tested more than 12 months ago have had significant time for cannabinoid and terpene degradation. Some states specify maximum intervals between testing and sale.
• Producer / Cultivator License Number: The state cannabis authority license number of the entity that produced the product. Verifiable against the state license database.
• Testing Laboratory License Number: The state cannabis testing laboratory license number. Should be verifiable against the state’s licensed lab list. An unlicensed lab produces a legally invalid COA.
• Sample Weight / Matrix: Specifies the amount tested and the product type (flower, concentrate, edible, tincture, topical). Different matrices require different testing protocols — the matrix designation confirms the correct protocol was applied.
• Accreditation Number: The ISO 17025 or equivalent accreditation identifier for the laboratory. Cross-referenceable with the accrediting body’s public database.

The cannabinoid panel is the first substantive section of the COA and documents the concentration of each detected cannabinoid as a percentage of total sample weight. A standard panel covers THCA, delta-9 THC, THCV, CBDA, CBD, CBGA, CBG, CBN, and CBC. Premium panels may measure 20 or more cannabinoids. Understanding how to read the panel correctly requires understanding the decarboxylation chemistry covered in depth in our THC percentages guide.

The Critical Distinction: Acidic vs. Neutral Forms

Raw, unheated cannabis contains primarily the acidic forms of cannabinoids: THCA, CBDA, CBGA. These are non-psychoactive precursors. When heated — through smoking, vaporization, or baking — the acid group (CO2) is removed by decarboxylation, converting THCA to THC, CBDA to CBD, and CBGA to CBG. A product might show 26% THCA and 0.4% THC on the COA panel. The 26% figure represents the dominant psychoactive potential; the 0.4% represents the tiny fraction already decarboxylated before use.

The Total THC Formula

The 0.877 factor is derived from the molecular weight ratio of the neutral to acidic form (molecular weight of THC ÷ molecular weight of THCA = 314.46 ÷ 358.47 = 0.877). This factor is consistent across all cannabinoid acid/neutral pairs because the decarboxylation reaction removes CO2 (molecular weight 44), and the neutral/acid ratio is approximately constant across the cannabinoid family.

Cannabinoid Panel Quick Reference

The terpene panel documents the aromatic compounds present in the product and their concentrations, typically expressed as a percentage. A comprehensive panel covers 20–30 individual terpenes. Understanding terpene data helps predict the experiential character of a product in ways that cannabinoid data alone cannot. Read our full terpene guide for detailed profiles of each.

Total terpene percentage is a useful quality proxy: products with total terpenes above 2% are generally fresh, well-cured, and aromatically rich. Products below 0.5% total terpenes have lost most of their terpene content through degradation, improper curing, or excessive heat during drying — regardless of their labeled THC%. A 26% THC flower with 0.3% total terpenes will frequently produce a less satisfying experience than an 18% THC flower with 2.8% total terpenes.

The pesticide panel is the most important safety section of the COA. Cannabis is a highly efficient bioaccumulator — its root system draws compounds including pesticides from soil and water into plant tissues with unusual effectiveness, concentrating them. Pesticides that might be present at trace levels in food crops can reach significant concentrations in cannabis, particularly in concentrates where plant material is processed into a fraction of its original volume (further concentrating any contaminants).

California tests cannabis for 66+ pesticide compounds; other states have comparable or larger panels. Pesticide categories include:

Every tested compound should show either “ND” (not detected, below the laboratory’s method detection limit) or a value below the state-set action limit. Action limits are set by toxicological risk assessment — they represent the maximum concentration at which regular exposure presents acceptable risk for the intended consumer population.

Why myclobutanil demands special attention: Myclobutanil is a demethylation-inhibiting fungicide widely used in conventional agriculture and one of the most commonly detected pesticides in unregulated cannabis. When cannabis containing myclobutanil residues is combusted or vaporized, the heat converts myclobutanil into hydrogen cyanide gas — a potent respiratory toxin. This specific pyrolysis product is the reason myclobutanil is explicitly banned for use on cannabis in all legal markets and is a first-priority pesticide to verify as absent when reviewing any COA for inhalable products.

Cannabis plants absorb heavy metals from contaminated soil or water with efficiency comparable to known phytoremediation species. This property makes them extremely effective at cleaning contaminated land — and equally effective at accumulating heavy metals that become harmful when consumed. The heavy metals panel tests for the four metals of primary toxicological concern.

For consumers with immunocompromised status, cancer treatment, or pre-existing kidney disease, the heavy metals panel should be reviewed carefully for any detectable levels above ND, since regulatory action limits are set for average healthy adult populations and may not be appropriate for all medical cannabis patients.

The microbial panel tests for harmful microorganisms that can cause serious illness, particularly in immunocompromised patients who are often the very consumers using cannabis medicinally. Cannabis flower, which is a plant material with surface areas hospitable to microbial growth, can harbor mold, bacteria, and pathogenic organisms if improperly cultivated, harvested, dried, or stored.

Standard microbial tests include: total aerobic microbial count (TAMC), total yeast and mold count (TYMC), pathogenic E. coli (primarily O157:H7 and other Shiga toxin-producing strains), Salmonella species, and Aspergillus species (A. fumigatus, A. flavus, A. niger, and A. terreus — the four species most commonly associated with opportunistic pulmonary infection in immunocompromised patients). California and several other states also test for mycotoxins (aflatoxins and ochratoxin A) produced by certain Aspergillus and Penicillium molds.

For healthy adult consumers, the microbial risk from licensed dispensary products that have passed testing is generally minimal. For patients undergoing chemotherapy, organ transplant recipients, HIV/AIDS patients, and others with significantly compromised immune systems, any mold presence in a cannabis product represents a genuine risk of pulmonary aspergillosis or other opportunistic infection. These patients should consult their medical provider before using any inhaled cannabis product and should prioritize edibles, tinctures, or other non-inhalation formats that eliminate respiratory exposure to potential microbial contaminants entirely.

Solvent-extracted concentrates — butane hash oil (BHO), CO2 oil, ethanol extract — must be tested for residual solvent levels. The solvents used in extraction must be purged from the finished product to below regulatory action limits. State action limits for key solvents (California, in parts per million):

Solventless concentrates (rosin, bubble hash) undergo no solvent extraction and therefore cannot have residual solvent contamination. This is a genuine quality and safety advantage of solventless products, not merely a marketing claim. Consumers who prioritize the absence of any potential solvent residual exposure should choose solventless formats.

COA verification is more important than most consumers realize. The cannabis industry has seen cases of falsified COAs — documents that appear to show passing test results but were fabricated, altered, or represent a different batch than the product being sold. A five-step verification process protects against this:

1. Scan the QR code on the product packaging. This should link directly to a live page on the testing laboratory’s own portal, not a downloadable PDF. Live portal pages cannot be altered after publication; PDFs can be. If the QR code links to a PDF hosted on the brand’s website, that is a lower-trust format.
2. Match the batch number exactly. The batch/lot number displayed on the lab portal must match the number printed on the product packaging precisely. Any discrepancy — even a single character or trailing zero difference — means the COA may not be for that product.
3. Verify the lab’s license. Look up the testing laboratory’s license number in your state cannabis regulatory agency’s public license database. An unlicensed lab produces a legally invalid COA regardless of its content.
4. Confirm ISO 17025 accreditation. Check the lab’s ISO 17025 accreditation status with A2LA, ANAB, or ORELAP (depending on the accrediting body identified on the COA). Accreditation databases are publicly searchable.
5. Check the test date. A COA more than 12 months old is questionable for current product quality and terpene data accuracy. In states with Metrc traceability, you can look up the product’s history in the state system to verify the COA date aligns with the product’s batch history.

• No COA available at all: Every licensed dispensary product must have associated lab testing. If unavailable, walk away.
• Static PDF only, no QR code: PDFs can be altered; a live lab portal page cannot. PDF-only COAs cannot be independently verified.
• Unlicensed or unaccredited lab: Testing by an unlicensed lab does not satisfy state testing requirements and provides no regulatory assurance.
• Cannabinoid-only panel — no safety testing: A COA that shows only THC and CBD percentages without pesticide, heavy metal, and microbial results is insufficient for safety verification.
• Test date more than 12 months ago: Products aged beyond this should have terpene panel data reviewed critically for degradation, and batch provenance should be questioned.
• Batch number mismatch: Any discrepancy between COA batch number and product packaging batch number is a red flag that the COA may not correspond to the actual product.
• THC% dramatically higher than comparable products: Consistent with industry potency inflation documentation. Products labeled 35%+ on flower are almost certainly the result of testing inaccuracies or lab shopping.
• Missing terpene panel on flower: Premium flower should always have terpene data. Absence may indicate the dispensary does not have it because the cultivator did not invest in full-panel testing.