Short answer: find the lot or batch number printed on your bottle, then find the published lab certificate that carries the same lot number. A certificate for a different lot, or with no lot number at all, does not prove anything about the bottle in your hand. Matching the two is the step that turns a certificate into evidence.
What a lot number is
A lot number (also called a batch number) is a code the manufacturer stamps on every production run, usually near the expiration date on the bottle base or the label seam. Everything made in that run shares the lot number. Lab testing is done per lot, because two runs of the same product can differ in potency and contaminants.
Why matching the lot is the whole point
This is the most common gap in supplement transparency. A brand publishes one impressive certificate, and shoppers assume it covers every bottle. It does not. The certificate only describes the lot it was run on. If your bottle is from a different run, that certificate is not evidence about your product. A report dated two years ago, for a lot number that is not on your label, tells you nothing about what you are about to take.
How to do the match, step by step
- 1. Read the lot number on the bottle. Look on the base, the crimp, or the label seam, usually next to the expiration date. Write down the exact string.
- 2. Find the brand's published certificate. Reputable brands post certificates by lot, either on the product page or a dedicated testing page.
- 3. Compare the lot numbers character by character. They must match exactly. A close-but-different number means a different run.
- 4. Confirm the certificate names an accredited lab and a date. A matching lot on a report from a lab you cannot verify is only half the check.
- 5. If it does not match, ask the brand. A transparent brand can produce the certificate for your specific lot. If they cannot, the certificate chain for your bottle is unverified.
What each result means
Lot matches a certificate from a named, accredited lab: the test applies to your bottle, and you are done. Brand publishes certificates but none matches your lot: the bottle is unverified until they provide the right one. Brand publishes no lot-level certificate at all: there is nothing to match against, which is a transparency gap rather than a judgement on the bottle.
The shortcut
ScanCheck does the matching for you. It holds a live index of 20,407 public certificates across 1,174 brands, organized so a scan resolves to the certificate for the batch, not just some certificate. Point your camera at the label: a green verdict means the brand has a public independent certificate on file, shown with the batch, lab, date, and method. Amber means the brand is indexed but this batch is not on file, so you can request it. Red means no public independent certificate exists to match.
Related: how to tell if a Certificate of Analysis is real and how to verify a supplement bought on Amazon.