My dispensary provides lab reports (COAs) for their products but I have no idea how to read them. What are the important numbers? What should I be concerned about? How do I know if a product is safe?
Editor-in-Chief
Reading a COA is one of the most valuable skills a cannabis consumer can develop. Here's a complete guide.
A Certificate of Analysis is a document from an accredited laboratory that reports the results of testing for a specific cannabis product. A complete COA should include: cannabinoid potency, terpene profile, pesticide screening, heavy metals, residual solvents (for concentrates), microbials (mold, bacteria), and moisture content.
This is the most-read section. Key numbers:
- Total THC: The total psychoactive THC content, including THCA converted to THC when heated. This is what determines potency.
- Total CBD: Total CBD content including CBDA.
- THCA: Raw, non-psychoactive form of THC. Multiply by 0.877 and add to THC for total THC.
- CBD:THC ratio: Important for medical patients. A 1:1 ratio means equal CBD and THC.
Red flags: Potency numbers that seem impossibly high (flower above 35% THC is extremely rare and may indicate testing fraud). Inconsistent numbers between batches of the same product.
Lists terpenes by percentage. Anything above 0.1% is significant. Look for:
- Myrcene (sedating, pain relief)
- Caryophyllene (anti-inflammatory, CB2 agonist)
- Limonene (mood elevation, anti-anxiety)
- Linalool (calming, sleep)
- Pinene (alertness, memory)
This is the most important safety section. The result should be "Pass" or "ND" (not detected) for all listed pesticides. Any detected pesticide above action limits is a fail.
Red flags: Any detected pesticide above the limit. Common problem pesticides: bifenazate, spiromesifen, myclobutanil (produces hydrogen cyanide when combusted).
Should show ND or below action limits for lead, cadmium, arsenic, and mercury. Heavy metal contamination is more common in cannabis grown in contaminated soil.
For vape cartridges and concentrates, check for residual solvents from the extraction process. Butane, propane, and ethanol should be below action limits.
Should show ND or pass for total yeast and mold, E. coli, Salmonella, and Aspergillus. Microbial contamination is particularly important for immunocompromised patients.
1. Check the lab name — is it an accredited lab? (ISO 17025 accreditation is the gold standard)
2. Check the date — COAs older than 12 months may not reflect current product
3. Check the batch number — does it match the product you are buying?
4. Scan the QR code if present — it should link to the lab's website with the original report
Our Lab Results Database includes COA data for major brands and transparency scores.
Community Member
Cannabis lab analyst here. Great answer from Sarah. One thing I want to add: the lab matters enormously.
Not all cannabis labs are created equal. Some labs have been caught "dry labbing" (issuing results without testing) or producing inflated potency numbers to attract business. Look for labs with ISO 17025 accreditation — this is the international standard for testing laboratory competence.
Also: the sample tested may not represent the entire batch. Labs test a small sample, and cannabis products can have significant variation within a batch. A COA is a quality indicator, not a guarantee.
Finally: if a product doesn't have a COA, or the dispensary can't provide one, that's a red flag. Any reputable dispensary should be able to provide COAs for all their products.