How to Read Cannabis Lab Test Results: THC, Pesticides, and More

To read cannabis lab test results, start with the certificate of analysis (COA), confirm the lab and sample date, then read the potency panel for total THC and check the contaminant panels for pass or fail results. A useful COA shows more than THC percentage: it also reports pesticides, microbials, heavy metals, and residual solvents.

how to read cannabis product label

What a Cannabis Certificate of Analysis Includes

A COA is the report a licensed lab issues after testing a specific batch of cannabis flower, concentrate, edible, or topical. The report should identify the lab, the sample, the product type, the test date, and the methods used. Results appear in panels, with a measured value and a pass or fail status against state limits. The COA is not a marketing sheet. It is a record tied to a batch.

Cannabis Label vs Test Results: Which One Do You Trust?

• Lab name and license number
• Sample ID, batch number, and product type
• Test date and report date
• Potency results for THC, THCA, CBD, and related cannabinoids
• Contaminant panels with pass or fail results

Read the Potency Panel: THC, THCA, and Total THC

Raw cannabis contains THCA, which converts to THC when heated. Labels often show THC, THCA, and total THC. A common formula for total THC is THC plus THCA multiplied by 0.877. That conversion factor accounts for the loss of a carboxyl group during decarboxylation. If a label lists only THCA and no total THC, do the math before comparing products.

cannabis label serving size

For edibles and tinctures, check milligrams per serving and servings per package. A high THC percentage on flower does not mean a better experience. Potency is one data point, not a quality score.

Check the Contaminant Panels

Contaminant results tell you whether the batch passed state limits. Look for the word pass, or a measured value below the listed limit. “Not detected” can be a good result, while a result below the limit of quantification means the lab could not measure it above that threshold. A fail on any panel matters, even if the potency number looks strong.

• Pesticides: screens for banned or restricted chemicals.
• Microbials: checks for yeast, mold, E. coli, and Salmonella.
• Heavy metals: tests for lead, arsenic, cadmium, and mercury.
• Residual solvents: applies to extracts and concentrates.
• Moisture and water activity: helps predict mold risk and shelf life.

Verify the Lab, Sample, and Date

Match the COA to the package in your hand. The batch or sample ID on the report should match the product label. Check the test date and the lab’s license. A COA from an unlicensed lab, or one with no sample ID, is hard to trust. QR codes on packaging can help, but confirm the code opens the same batch report, not a generic page.

Red Flags When You Read Cannabis Lab Test Results

• No lab name, license number, or sample ID.
• Potency results with no contaminant panels.
• Results that do not match the package batch.
• Edited or handwritten PDFs.
• “Pass” claims with no listed limit or method.
• THC numbers that look impossible for the product type.

Quick Checklist Before You Buy

1. Confirm the COA matches the batch on the label.
2. Find total THC, not just THCA.
3. Check pesticides, microbials, heavy metals, and solvents.
4. Look for pass results against state limits.
5. Ask the dispensary staff if a report is missing.

Reading a COA takes a minute, but it turns a vague potency label into a clear picture of what you are buying.