How to read a Certificate of Analysis (COA)
A Certificate of Analysis (COA) is a third-party lab test that documents what's actually in a cannabis product. Every reputable hemp brand publishes one for each batch. Here's how to read them in 30 seconds and spot the brands that are hiding something.
The header — batch identifiers
Top of the page lists:
- Sample ID / batch number — should match the batch number on your jar
- Sample collection + analysis dates — fresher is better; over 12 months is concerning for terpenes
- Lab name + accreditation — ISO 17025 accreditation is the gold standard
- Strain or product name — should match what you bought
Red flag: missing batch number, unaccredited lab, or analysis date over a year old.
Cannabinoid potency panel
Lists every cannabinoid detected with percentage by dry weight. For THCa flower:
- THCa: the headline number (e.g. 25.3%) — what produces the high after heating
- Delta-9 THC: must be ≤ 0.3% for federal hemp compliance
- Total THC: calculated as (THCa × 0.877) + Delta-9 THC
- CBD, CBG, CBN, CBC: minor cannabinoids, present in small amounts in full-spectrum flower
Red flag: Delta-9 THC over 0.3% (not federally compliant), or "ND" (not detected) on every minor cannabinoid (suggests over-processed or mislabeled product).
The contaminant panels — must all pass
Four contaminant categories. Every one needs a "PASS" indicator:
- Pesticides — residues from cultivation. Failures here are most common in cheap import flower.
- Heavy metals — lead, arsenic, cadmium, mercury. Plants accumulate from soil.
- Mycotoxins — toxins from mold contamination. Critical for inhaled products.
- Microbials — bacteria, mold, yeast, salmonella, E. coli. Critical for any cannabis product.
- Residual solvents (concentrates only) — leftover butane, ethanol, etc. from extraction.
Red flag: any "FAIL" or missing panel. A reputable brand publishes all four.
Terpene profile
Lists every terpene detected with percentage. The dominant terpene (highest %) predicts the strain's effect more than the strain bucket alone.
Look for: 1.5-3% total terpene content (good), with one or two clear leaders. Below 1% suggests over-processing or aged flower. Above 3.5% is unusually fresh.
Red flag: every terpene listed at "ND" — the brand probably didn't pay for the terpene panel, which is a red flag in itself for a premium product.
Frequently asked questions
What if a brand doesn't publish a COA?
Don't buy from them. There's no legitimate reason to hide a lab test for a hemp product in 2026. Every reputable brand has them on the website or available on request.
How recent does the COA need to be?
For the batch you're buying, ideally within 3-6 months. Cannabinoid content is stable for 12-18 months when stored properly; terpenes fade faster. Avoid flower with COAs over a year old.
What's the difference between THC and Total THC?
THC alone (Delta-9) is the active form. Total THC includes the THCa converted to its post-heating equivalent. For hemp legality, only the Delta-9 number matters. For experience, the total THC number predicts the high.
Should the lab be independent of the brand?
Yes. The COA is meaningful only if the lab is truly third-party. ISO-accredited labs with no ownership ties to the brand are the standard. Brand-owned labs are a red flag.