Why do some peptide sellers charge so much more for the same milligram amount?

A higher price per milligram sometimes reflects a smaller vial, since price per milligram falls as vial size grows across nearly every compound this site tracks. It can also reflect testing and sourcing costs that a cheaper competitor has not paid for. It is not, by itself, evidence of higher purity: only an independently verifiable certificate of analysis tells you that, and this site's pricing pages hold vial size constant precisely so the comparison is fair.

Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.

Part of buying, vendors, and lab testing. How to evaluate a seller's claims, certificates of analysis, and pricing.