How to Read a Hemp COA (Certificate of Analysis)
A beginner-friendly guide to trying THCA flower for the first time. What it is, how it works, and what to expect from your experience.
A Certificate of Analysis (commonly called a COA) is one of the most important tools available to hemp consumers. It's also one of the least understood.
If you've ever looked at a COA and felt overwhelmed by the numbers, abbreviations, and lab terminology, you're not alone. Most consumers skip them entirely. But learning to read a COA takes less time than you might think, and it puts you in a much stronger position to evaluate what you're actually buying.
This guide walks through each section of a typical hemp COA and explains what to look for.
What Is a COA?
A Certificate of Analysis is a document produced by a third-party laboratory that summarizes the results of testing performed on a specific product or batch.
For hemp products, a COA typically covers:
• What cannabinoids are present and in what amounts
• Whether the product meets legal thresholds for delta-9 THC
• Basic identifying information about the sample and lab
• Depending on the scope of testing, additional panels such as contaminants or terpenes
The key detail is "third-party." A credible COA comes from an independent, qualified laboratory, not the brand selling the product. This separation is what gives the document its value.
The Header: Who, What, and When
The top of a COA usually contains identifying information:
• Lab name and accreditation — the laboratory that performed the testing. Look for ISO 17025 accreditation or state licensing. These indicate the lab follows standardized procedures.
• Sample name or product ID — what was tested. This should correspond to the product being sold. Some COAs use a lab-assigned sample ID, while others include a batch or lot number provided by the producer.
• Identifying information — whether it's a batch number, sample ID, or internal tracking code, there should be a clear way to connect the COA to the specific product being sold. Reputable retailers make this connection visible on their product pages.
• Date of testing — when the analysis was performed. More recent is generally better, especially for flower products that can change over time.
If a COA lacks any identifying information connecting it to a specific product, that's worth questioning.
Cannabinoid Profile: The Core of the Report
This is the section most consumers look at first, and for good reason. It tells you what's in the product.
Common cannabinoids listed include:
• THCa (tetrahydrocannabinolic acid) — the primary cannabinoid in THCa flower. This is the compound that converts to THC when heated. Higher THCa typically indicates more potency when consumed through smoking or vaporization.
• Δ9-THC (delta-9-tetrahydrocannabinol) — the compound that determines legal status. Under federal law, hemp must contain no more than 0.3% delta-9 THC by dry weight. This number is the compliance threshold.
• CBD (cannabidiol) — a non-intoxicating cannabinoid associated with calm and balance. Some hemp products are CBD-dominant; THCa flower typically contains minimal CBD.
• CBG, CBN, CBC — minor cannabinoids that may appear in smaller amounts. Their presence can vary by strain and processing.
Results are usually shown as a percentage (%) or in milligrams per gram (mg/g).
What to check:
• Does the delta-9 THC level fall at or below 0.3%?
• Does the THCa content match what's advertised on the product page?
• Are results reported as "per dry weight" for flower, or per unit for edibles?
For a detailed explanation of how THCa relates to THC, see Understanding THC: How Delta-9, THCa, and Related Compounds Actually Work.
Total THC: A Common Point of Confusion
Some COAs include a "Total THC" calculation. This uses a formula to estimate the maximum amount of THC that could be present if all the THCa in the product were to convert into THC through decarboxylation.
The formula is:
Total THC = (THCa × 0.877) + Δ9-THC
The 0.877 factor accounts for the molecular weight lost when THCa converts to THC.
This number is not the same as the delta-9 THC measurement used for federal compliance. Legal hemp status is currently determined by delta-9 THC concentration alone, not total THC, though this is an area of ongoing regulatory discussion.
Understanding this distinction helps avoid confusion when reviewing test results.
Terpene Profile (When Included)
Not all COAs include terpene testing, but those that do provide useful context about flavor, aroma, and potential effects.
Common terpenes you may see listed:
• Myrcene — earthy, musky. Associated with relaxation.
• Limonene — citrus. Linked to mood elevation.
• Caryophyllene — peppery, spicy. Studied for potential anti-inflammatory effects.
• Pinene — fresh pine. May support alertness.
• Linalool — floral, lavender. Associated with calming effects.
Terpene data can help explain why two strains with similar THCa percentages may feel noticeably different.
Contaminant Testing: What Should Not Be There
A thorough COA may also include screening for contaminants. The scope of testing depends on the product type, the lab, and the level of analysis requested. Common contaminant panels include:
• Pesticides — chemical residues from cultivation
• Heavy metals — lead, arsenic, cadmium, mercury
• Microbials — mold, yeast, bacteria (E. coli, salmonella)
• Residual solvents — chemicals used in extraction processes (relevant for concentrates)
• Mycotoxins — toxic compounds produced by certain molds
Results are usually listed as "pass" or "fail," or with specific measurements compared against safety thresholds.
The scope of testing included in a COA can vary depending on the product type, the supplier, and the lab. Cannabinoid potency testing is the most common baseline. Full-panel testing, which includes contaminants, terpenes, and safety screenings, represents a more comprehensive standard and is increasingly common as the industry matures.
For more on why testing scope matters, see Why Lab Testing Matters for Hemp Products.
Red Flags to Watch For
A COA can reveal problems if you know what to look for:
• No identifying information connecting the COA to the product being sold
• Expired or outdated testing — especially for flower that may have been stored for months
• Limited transparency about testing scope — if a brand can't explain what was tested and why, that's worth nothing.
• No verifiable lab information — if the COA doesn't identify a real, contractable laboratory, that's a concern.
• Results that don't match the product listing — if a brand advertises 35% THCa but the COA says 28%, something is off
• No COA available at all — the biggest red flag. If a brand can't or won't share lab results, reconsider the purchase.
For a broader look at what to watch for when shopping, see Red Flags to Avoid When Buying Hemp Products Online.
How Ember Trees Handles Testing
Every product in the Ember Trees collection is backed by a third-party Certificate of Analysis. Each product is assigned an internal Ember Trees batch number that links directly to its corresponding COA on the product page.
The scope of testing varies by product and supplier. Some COAs include full-panel results covering contaminants and terpenes, while others focus on cannabinoid potency and compliance.
All COAs are accessible directly from each product page so consumers can review test results before making a decision.
Explore Further
Educational Notice
This article is provided for educational purposes only and reflects current regulatory understanding. COA formats and testing standards may vary by laboratory and jurisdiction. This content is not intended as medical or legal advice.
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