Understanding Cannabis Lab Tests & COAs

Every legal cannabis product sold in regulated markets must pass testing at an independent, state-licensed laboratory before it reaches dispensary shelves. The results of this testing are documented in a Certificate of Analysis (COA) — a detailed report that tells you exactly what's in your product and confirms it's safe to consume. Understanding COAs helps you make better purchasing decisions and ensures you're getting what you pay for.

What Cannabis Labs Test For

State-licensed cannabis testing laboratories perform a battery of tests on every batch. The specific tests required vary by state, but most regulated markets require the following categories.

1. Potency (Cannabinoid Profile)

Potency testing measures the concentrations of major cannabinoids in the product. This is what determines the THC and CBD percentages on the label.

• THC (delta-9-tetrahydrocannabinol): The primary psychoactive compound. Reported as a percentage of total weight for flower and concentrates, or as milligrams per unit for edibles.
• THCA (tetrahydrocannabinolic acid): The precursor to THC. Raw cannabis contains THCA, which converts to THC when heated (decarboxylation). Labels typically show "Total THC" = THCA x 0.877 + delta-9 THC.
• CBD (cannabidiol): The primary non-psychoactive cannabinoid. Important for therapeutic use and for moderating THC effects.
• CBN (cannabinol): A mildly psychoactive compound associated with sedation. Formed as THC ages.
• CBG (cannabigerol): A non-psychoactive cannabinoid with emerging research on anti-inflammatory and neuroprotective properties.
• Other cannabinoids: THCV, CBC, delta-8 THC, and others may also be tested depending on the product and state requirements.

2. Terpene Profile

Terpene testing identifies the aromatic compounds that give cannabis its flavor and may influence its effects through the entourage effect. Common terpenes tested include myrcene, limonene, linalool, pinene, caryophyllene, humulene, and terpinolene. Terpene testing is not required in all states but is becoming more common as consumers learn to shop by terpene profile rather than strain name alone.

3. Pesticide Screening

Labs screen for dozens of pesticides that are prohibited or restricted in cannabis cultivation. California, for example, tests for over 60 pesticide compounds. Products must show non-detectable levels or levels below established action limits to pass. This is critical because cannabis is consumed through inhalation and ingestion — routes that can deliver pesticide residues directly into the body.

4. Heavy Metals

Cannabis plants are bioaccumulators — they absorb substances from the soil, including heavy metals. Labs test for lead, arsenic, cadmium, and mercury, which are toxic even at low concentrations. Heavy metal contamination is one of the strongest arguments for buying lab-tested, licensed products rather than unregulated cannabis.

5. Microbial Contaminants

Microbial testing checks for harmful bacteria, mold, and fungi. Key organisms tested include Aspergillus (a mold that can cause serious lung infections), E. coli, Salmonella, and total yeast and mold counts. This testing is especially important for immunocompromised patients and for products that will be smoked or vaped.

6. Residual Solvents

Products made with solvent-based extraction methods (BHO, ethanol, CO2) must be tested for residual solvents. Common solvents tested include butane, propane, ethanol, isopropanol, and hexane. These chemicals must be below established safety thresholds — typically measured in parts per million (ppm).

7. Moisture Content & Water Activity

For flower products, labs measure moisture content and water activity. Excessive moisture promotes mold growth, while too-dry flower loses terpenes and burns harshly. Ideal moisture content is 8-12%, and water activity should be below 0.65 aw (activity of water) to prevent microbial growth during storage.

How to Read a COA

COAs can look intimidating with their charts, numbers, and scientific terms. Here's a straightforward guide to interpreting the key sections.

1. Find the sample info: Look for the product name, batch number, sample date, and the lab's name and license number. Verify the batch number matches the product you purchased.
2. Check potency: Look for the Total THC and Total CBD numbers. These should match what's on the product label (within a reasonable margin, typically +/- 10%). See our label reading guide for more on interpreting THC/CBD numbers.
3. Review safety tests: Each contaminant category (pesticides, heavy metals, microbials, solvents) should show "PASS" or "Not Detected." If any category shows "FAIL," the product should not be on shelves.
4. Check the terpene profile: If included, terpenes are listed by name with concentrations in percentage or mg/g. The top 2-3 terpenes determine the dominant flavor and may hint at effects.
5. Verify the lab: The COA should include the lab's name, license number, and the analyst's signature or certification. You can verify California labs at the DCC website.
6. Look at the date: COAs are batch-specific. Older results may not reflect the current product, especially for cannabinoid potency, which can degrade over time.

Why Lab Testing Matters

Lab testing is the primary safeguard that separates the legal cannabis market from the unregulated market. Without testing, you have no way to verify potency claims, and you risk exposure to potentially harmful contaminants.

• Accurate potency: Untested products frequently misrepresent THC and CBD levels. Studies of unregulated products have found THC content that differs from labels by 50% or more.
• Safety: Pesticides, heavy metals, and mold can cause serious health problems, especially with chronic exposure or for immunocompromised users.
• Consistency: Testing ensures batch-to-batch consistency, so you know what to expect each time you purchase a product.
• Legal compliance: In regulated markets, untested or failed products cannot legally be sold. When you buy from licensed dispensaries, every product has passed mandatory testing.
• Find lab-tested products at licensed dispensaries in your area.

How to Find COAs for Products You Buy

1. Scan the QR code: Many products include a QR code on the package that links directly to the COA for that batch.
2. Check the brand's website: Reputable brands publish COAs on their websites, organized by product and batch number.
3. Ask your budtender: At a licensed dispensary, staff should be able to pull up COAs for any product on their shelves.
4. Look for the batch number: Every legal product has a batch or lot number on the label. Use this number to request or search for the corresponding COA.
5. Browse products from trusted brands in our directory.

Explore our product catalog to find lab-tested products, or visit dispensaries near you to ask budtenders about COAs. For more on understanding what's on a label, see our label reading guide.