# COA

> A COA (certificate of analysis) is a lab's signed report of what it measured in a specific sample, such as cannabinoids, terpenes, moisture and contaminants, with methods and limits.

- Canonical: https://genetixbay.com/knowledge/glossary/coa.html
- Also written: certificate of analysis, C of A, lab certificate, lab report, test results sheet
- Glossary category: Lab testing · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

A certificate of analysis is the formal report a testing laboratory issues for a sample. A complete COA identifies the lab and its accreditation, the client, the sample and batch ID, [sampling](https://genetixbay.com/knowledge/glossary/homogenisation.md) and receipt dates, the methods used, each result with units, the [LOD](https://genetixbay.com/knowledge/glossary/lod.md) or LOQ, pass/fail against any limits, and a signature from an authorised analyst.

## In practice

Read a COA from the top: is it the right product and batch, from a lab accredited for that method, dated recently? Then check the basis ([dry weight](https://genetixbay.com/knowledge/glossary/dry-weight.md) or [as received](https://genetixbay.com/knowledge/glossary/dry-weight-basis.md)), the moisture figure, and whether "total [THC](https://genetixbay.com/knowledge/glossary/thc.md)" was calculated with the [0.877](https://genetixbay.com/knowledge/glossary/total-thc.md) factor. A flower COA reading 20.4% total THC at 11% moisture as received is a coherent document. One reading 38% with no moisture data and no method reference deserves suspicion.

A COA describes only the sample the lab received. It does not prove that every jar from the batch matches, and it says nothing about samples the lab never saw.

## Don't confuse with

- **Label**: the number printed on retail packaging, which may be rounded or taken from a different test.
- **Spec sheet**: a seller's description, not an independent measurement.

## Myth check

A COA is only as good as the sample and the lab. House position: [inflated labels](https://genetixbay.com/knowledge/glossary/label-inflation.md) and [lab shopping](https://genetixbay.com/knowledge/glossary/lab-shopping.md) are well documented (Jikomes & Zoorob 2018; Schwabe et al. 2023). See [buyer beware](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md).

## Related terms

[Potency testing](https://genetixbay.com/knowledge/glossary/potency-testing.md), [Total THC](https://genetixbay.com/knowledge/glossary/total-thc.md), [LOQ](https://genetixbay.com/knowledge/glossary/loq.md), [Batch](https://genetixbay.com/knowledge/glossary/batch.md), [ISO/IEC 17025](https://genetixbay.com/knowledge/glossary/iso-17025.md), [Lab shopping](https://genetixbay.com/knowledge/glossary/lab-shopping.md)

## Read more

- [Buyer beware: potency labels, strain names and other claims that don't hold up](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md)

## Sources

1. ISO/IEC 17025:2017. General requirements for the competence of testing and calibration laboratories. International Organization for Standardization, Geneva.
2. Schwabe AL, Johnson V, Harrelson J, McGlaughlin ME. 2023. Uncomfortably high: Testing reveals inflated THC potency on retail Cannabis labels. PLOS ONE 18(4):e0282396. https://doi.org/10.1371/journal.pone.0282396