LAB TESTING GUIDE · UPDATED AUGUST 2026
How to Read a COA for THC Products
A Certificate of Analysis, or COA, can help you understand what a laboratory found in a tested product or batch. The most useful COAs let you verify the batch, cannabinoid potency, reporting limits, testing laboratory, and any contaminant panels that were actually performed.
QUICK ANSWER
How to Check a COA in About 60 Seconds
Start by confirming that the COA belongs to the product in your hand. Then check the laboratory, test date, cannabinoid results, reporting units, and which contaminant panels were actually tested. A COA is useful evidence about a tested sample or batch, but it is not an absolute guarantee of product safety or quality.[1][2]
What Is a Certificate of Analysis?
A Certificate of Analysis is a laboratory report that records analytical results for a tested sample or batch. Depending on the product, laboratory, jurisdiction, and requested test panel, a COA can include cannabinoid potency and results for contaminants such as residual solvents, pesticides, heavy metals, microbial impurities, or mycotoxins.
A COA should not be treated as a universal guarantee that a product is “safe.” It tells you what was tested, how the result was reported, and what the laboratory found in the sample it analyzed. Testing that was not performed cannot be inferred from the report.
Regulators in established cannabis testing programs use COAs to report potency and contaminant results and to document whether a tested batch meets applicable testing standards.[2]
Step 1: Make Sure the COA Matches Your Product
Before reading cannabinoid numbers, verify that you are looking at the correct report.
Compare the batch number, lot number, production identifier, or other identifying information on the package with the information on the COA. Also check the product name and testing date.
This is one of the simplest and most important checks. A legitimate laboratory report is not useful to you if it belongs to a different batch.[3]
GOOD PRACTICE
If a QR code opens a generic testing page, do not stop there. Find the report that matches the actual batch or lot identifier on your product.
Step 2: Identify the Laboratory
A useful COA should identify the testing laboratory and the report. Look for the laboratory name, address or contact information, report or sample identifier, analysis date, and authorized approval or signature where applicable.
Laboratory accreditation can add another layer of confidence in the laboratory's technical system. ISO/IEC 17025 is the international standard used to assess the competence, impartiality, and consistent operation of testing and calibration laboratories.[1]
Accreditation does not make every result infallible. It means the laboratory has been assessed against a recognized standard for laboratory competence.
Step 3: Read the Cannabinoid Profile
The cannabinoid section reports the compounds the laboratory measured. Depending on the method and product, this can include Delta-9 THC, THCA, Delta-8 THC, CBD, CBDA, CBG, CBN, and other cannabinoids.
Always read the number together with its unit. A result such as “10” means very little until you know whether the report means 10 mg per unit, 10 mg per gram, 10 mg per package, or 10%.
Percentage vs. Milligrams: How Do You Read Potency?
Different products are often easier to understand in different units. Flower and other plant material are commonly discussed as percentages. Manufactured products such as gummies are often easier to understand in milligrams per serving or package.
| Reported Unit | What It Means |
|---|---|
| % | Parts per hundred by weight. One percent equals 10 milligrams per gram. |
| mg/g | Milligrams of the cannabinoid in one gram of tested material. |
| mg/unit | Milligrams in one individual item, such as one gummy, if the report uses that unit. |
| mg/package | Total milligrams reported for the complete retail package. |
SIMPLE POTENCY EXAMPLE
If a product weighs 4 grams, that equals 4,000 milligrams. If the product contains 0.25% of a cannabinoid by weight, the mathematical equivalent is:
4,000 mg × 0.0025 = 10 mg.
The calculation only works when the percentage and product weight refer to the same basis. Always use the units and definitions shown on the actual laboratory report.
What Does “Total THC” Mean?
Some laboratory reports distinguish Delta-9 THC from total THC. Total THC can account for THCA that can convert to THC through decarboxylation.
USDA hemp compliance testing, for example, requires total THC testing that accounts for the potential conversion of THCA to THC and reports the result on a dry-weight basis.[4]
This is one reason you should not assume that “Delta-9 THC” and “Total THC” are interchangeable fields on a COA.
What Do ND, LOD, and LOQ Mean?
Laboratory reports often contain abbreviations that are easy to misread.
| Term | Meaning |
|---|---|
| ND | Usually means “not detected” under the laboratory's method and reporting conditions. It should not automatically be interpreted as absolute zero. |
| LOD | Limit of Detection. The lowest level the method can reliably distinguish from background or a blank. |
| LOQ | Limit of Quantitation. The lowest amount the method can quantify with acceptable accuracy and precision. |
NIST defines the limit of detection as the lowest concentration that can be reliably distinguished from the blank matrix. NIST defines the quantitation limit as the minimum amount that can be quantified with acceptable accuracy and precision.[5][6]
So a result reported as “ND” or “below LOQ” should not automatically be read as proof that the analyte is completely absent.
Step 4: Check the Contaminant Panels
Do not assume that a potency COA also includes full contaminant testing. Look at the report and identify which panels were actually performed.
Depending on the testing program and product type, contaminant panels can include:
- Residual pesticides
- Heavy metals
- Residual solvents and processing chemicals
- Microbial impurities
- Mycotoxins
- Foreign material
- Moisture content or water activity
Established cannabis testing programs require many of these categories because cannabinoid potency alone does not describe product contamination.[2]
What Does “Pass” or “Fail” Mean?
A pass or fail result only makes sense in relation to a defined testing standard or action limit. If the report uses pass/fail language, identify what standard or specification the laboratory used.
A result can also be numeric without a pass/fail designation. That does not necessarily make the report invalid. It means the consumer may need more context about the applicable specification or regulation.
Can You Trust Every COA?
A COA is an important transparency tool, but laboratory testing is still a human and technical process. Sampling, sample preparation, analytical methods, calibration, laboratory quality systems, and reporting practices all affect the reliability of a result.
ISO/IEC 17025 focuses on laboratory competence and consistent operation, while USDA hemp testing guidelines also require laboratories to use appropriate validated methods and quality assurance procedures for compliance testing.[1][4]
Regulators have also identified “lab shopping” as a testing-integrity concern in cannabis markets. In 2026, California's Department of Cannabis Control proposed additional safeguards specifically aimed at preventing parties from sending a batch to multiple laboratories and selecting only the most favorable result.[7]
COA RED FLAGS
- The batch or lot cannot be matched to the product.
- The report does not identify the laboratory.
- The test date is unusually old for the product.
- The units are unclear or missing.
- A seller claims “full panel tested,” but the COA only shows cannabinoids.
- The QR code leads to a generic report instead of the relevant batch.
- The company will not provide testing when asked.
Does a COA Prove a THC Product Is Safe?
No. A COA should be viewed as evidence from a laboratory test, not as a blanket safety guarantee.
The report only addresses the sample tested, the analytes included, the laboratory's methods, and the applicable reporting limits. It cannot tell you the result of a test that was never performed.
This distinction is especially important for manufactured cannabinoids. FDA has warned that some Delta-8 manufacturing processes can create unwanted by-products or contaminants, which is one reason transparent testing matters.[8]
How Should You Access a COA?
A company can make COAs available through a testing page, QR code, product page, or customer service request. The method is less important than whether you can locate a report that clearly corresponds to the product or batch.
Frequently Asked Questions
What does COA stand for?
COA stands for Certificate of Analysis. It is a laboratory report that records analytical results for a tested sample or batch.
Does every COA test for contaminants?
No. A COA only reports the analyses performed. Check the report to see whether it includes pesticides, heavy metals, residual solvents, microbes, or other contaminant panels.
Does ND mean there is absolutely none of a substance present?
Not necessarily. “Not detected” generally means the analytical signal did not meet the method's detection or reporting threshold. Detection limits depend on the method and laboratory.[5]
What is the most important thing to check first?
Match the COA to the product's batch or lot number. If the report belongs to another batch, its test results do not establish what was found in the product you purchased.
Is an ISO/IEC 17025 accredited lab better?
ISO/IEC 17025 accreditation indicates that the laboratory has been assessed against an international standard for testing competence, impartiality, and consistent laboratory operation. It is a meaningful quality signal, but it does not guarantee that every individual result is error-free.[1]
TESTED WITH TRANSPARENCY
Match the Product to the Lab Results.
Door County Cannabis Co. believes customers should be able to see the testing behind the products they buy. Our testing page provides access to available laboratory reports so you can review cannabinoid results and product information directly.
A lab report is most useful when you know how to read it. Check the batch, identify the laboratory, understand the units, and review the panels that were actually tested.
Sources & Further Reading
- International Organization for Standardization. ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories. View ISO standard overview .
- California Department of Cannabis Control. Testing laboratories and required cannabis testing. View testing requirements .
- California Department of Cannabis Control. Representative sampling checklist for distributors. View batch and COA guidance .
- U.S. Department of Agriculture, Agricultural Marketing Service. Laboratory Testing Guidelines for the U.S. Domestic Hemp Production Program. View USDA laboratory guidelines .
- National Institute of Standards and Technology. Limit of Detection. View NIST definition .
- National Institute of Standards and Technology. Quantitation Limit. View NIST definition .
- California Department of Cannabis Control. 2026 Track and Trace Updates and proposed safeguards addressing laboratory shopping. View 2026 rulemaking .
- U.S. Food and Drug Administration. 5 Things to Know About Delta-8 THC. View FDA guidance .
This article is for general educational purposes. Laboratory methods, regulatory requirements, action limits, and reporting practices can vary by product and jurisdiction. A Certificate of Analysis should be interpreted in the context of the specific sample, method, laboratory, and testing requirements.
