One-pager
How to read a Certificate of Analysis.
A Certificate of Analysis, or COA, is the laboratory's record of what it measured on one batch. It is a plain measurement document, and once you know its five columns you can read any of them. This page explains every part.
01
Anatomy of a certificate
Every COA is laid out the same way, whichever laboratory issued it.
- The headerWho issued the certificate and when. On our copies the laboratory and manufacturer names are blacked out; the issue date and page numbers are not.
- Sample identityThe product name, the lot or batch number, and the expiration date. This is the block to check against your own bottle: a certificate is only about the batch it names.
- The test tableOne row per test. Every row carries the same five columns, explained below. Nothing is left out: tests that are reported for information only appear alongside the ones that pass or fail.
- The conclusion columnPass, Fail, or Information only, decided by comparing the result against the specification in the same row, not by anyone's judgement after the fact.
- The signature blockThe analyst or quality lead who approved the release, and the standard note that results relate only to the sample tested.
02
The five columns
Every row of the test table carries these five, in this order. Read them left to right and the row explains itself.
- Test
- The property being measured: an ingredient, a metal, an organism, a physical characteristic.
- Method
- The instrument or standard procedure used. Open any method chip on a results page for a plain description of it.
- Result
- The number the laboratory actually got. A “<” in front of it means the substance was below the lowest amount the instrument can reliably report.
- Specification
- The limit the batch was measured against. Specifications are written down before testing starts, so they cannot be moved to fit a result.
- Conclusion
- Whether the result fell inside the specification. “Information only” means the test was reported but has no limit attached.
A worked example. Loss on drying · USP <731> · 2.8% · NMT 5.0% · Pass reads as: the laboratory dried a sample to measure its moisture using the standard method, found 2.8%, and the batch was required to be at or under 5.0%, so the row passes.
03
What gets tested
Results on this site are grouped into five families. Each one answers a different question.
- IdentityConfirms the capsule contains what the label says it does.
- Active ingredientsHow much of the active ingredient each capsule actually contains.
- Heavy metalsTrace metals found in soil and water. Limits are set per day of use.
- MicrobiologyBacteria, yeast and mold counts. "Absent" means none detected in the sample.
- Physical & purityWeight, moisture and how the capsule breaks down.
On any results page, the name of a test carries a “?” and so does its method chip. The first explains what the test checks; the second explains how it is measured.
04
Abbreviations and symbols
Laboratories write tersely. This is the whole vocabulary you need.
- NMT
- Not more than: an upper limit. “NMT 5.0%” means anything up to 5.0% passes.
- NLT
- Not less than: a lower limit, used for the ingredients the label declares.
- <
- Below the reporting limit. The instrument found nothing it could measure reliably at or above that number.
- cfu/g
- Colony-forming units per gram: how many living microbes grew from one gram of sample.
- Absent
- None recovered from the sample size stated next to it, usually 10 grams.
- mcg/day
- Micrograms per day at the serving size printed on the label. Heavy-metal limits are set per day of use, not per capsule.
- % w/w
- Weight for weight: grams of the measured substance per 100 grams of material.
- ppm / ppb
- Parts per million and parts per billion. One ppb is roughly one second in 32 years.
- Conforms
- The sample matched the written reference the laboratory compared it against.
- USP <2021>
- A numbered chapter of the United States Pharmacopeia: a published, standardised procedure any accredited lab can follow.
05
Who ran the test
The single most useful thing to check on any certificate, and the reason it appears at the top of every lot page here.
An accredited laboratory with no financial interest in the product. It is paid to measure, not to pass.
The laboratory inside the facility that produced the batch. Routine and legitimate (it runs the same standardised methods), but the tester and the maker are the same organisation, and you should know that when you read the result.
06
What a certificate can't tell you
Being clear about the edges of the document is part of reading it honestly.
- It describes one batch.A certificate says nothing about the batch before it or the batch after it. That is why every lot code on this site has its own page.
- It describes a sample.The laboratory tests a sample drawn from the batch under a sampling plan, not every capsule in every bottle.
- It is a measurement, not a claim.A certificate records what was measured. It does not say what the product does, and no result on this site should be read as a health claim.
- “Pass” is specific.It means the batch met the written limit for that one test. It carries no meaning beyond the row it sits in.
Now read your own.
Enter the lot code stamped on the bottom of your bottle and every column above will be sitting there, filled in.