What we test for

Short version: a lab checks the product, we publish what it found. No vendor can pay us to change a number, and nothing here is medical advice.

A lab report on a submitted sample generally tells us two things:

• How pure it is - whether the vial contains what it claims to, and how much of anything else (contaminants, degradation products) shows up alongside it.
• How much is actually in the container - the measured amount compared to what the label or listing claims, expressed as a percentage difference.

We also note whether a vendor communicates batch-specific information (for example, printed on the vial or the packaging) versus only on a web page at checkout. Clear, on-container batch information is more useful to a buyer than a claim that only exists on a website, so it factors into how a test is reviewed.

Where samples come from

Most samples are sourced directly by PeptideScore from vendor listings, so we can document chain of custody from purchase to lab.

Members of the public can also send in a vial they already own for free testing. If you'd like to submit one, see our free sample testing page for what we accept and how shipping works.

How a test becomes a score

Once lab results come back, a member of our team reviews the purity reading, the quantity accuracy, and the batch information described above, and assigns the sample a score from 0 to 10. A perfect 10 means the lab confirmed the product matched its claims closely and the vendor documented the batch clearly; a low score reflects meaningful gaps in purity, quantity, or transparency.

We are not publishing a fixed point formula for this step, because lab reports vary in what they measure and how they report it, and a rigid formula would force reviewers to ignore context that actually matters to a buyer. What we do publish, always, is the underlying lab report itself alongside the score, so you can form your own judgment.

From individual test scores to a rating

A vendor's rating for a given product is the average of every test score we've recorded for that product/vendor pair. We also track the lowest score received and the total number of tests, and show both next to the rating so you can see how much data backs it up.

That average maps to a letter grade:

A product/vendor pair with no recorded tests yet is shown as unrated rather than guessed at. We'd rather tell you we don't have data than assign a grade we can't back up.

Keeping ratings current

A rating recalculates automatically the moment a new test is added for that product/vendor pair, so you're never looking at a stale average.

Individual test scores are not revised after the fact except to correct a factual error, and if that happens we say so.

What a rating does not mean

A high rating is not a medical endorsement, and it doesn't mean a product is legal to buy, sell, or use where you live. It only tells you what the samples we tested measured in the lab, nothing broader than that.

Questions about a specific rating, or suggestions for how we can test more thoroughly, are welcome through our contact page.