How $/mg works: how we calculate and compare peptide prices
$/mg is the listed price of a vial divided by the milligrams of peptide it states, in US dollars, excluding shipping. It lets a 5 mg vial and a 10 mg vial be compared on equal terms. Every figure on this site is dated and refreshed nightly.
Example: a 10 mg vial listed at $50 is $5.00/mg; a 5 mg vial listed at $30 is $6.00/mg. The 5 mg vial costs less in total but more per milligram. This page is the complete rule set behind the numbers on every price comparison, price guide and monthly price report. Methodology version 1.5.1.
Where the prices come from
- Public catalog pages only. Every night we read the public product pages of US research-peptide storefronts. No vendor accounts, no checkout probing; if a price is not publicly listed, it is not in the index.
- US-based resellers only. Overseas storefronts are out of scope, so every comparison is between like and like.
- Computed, then dated. Each figure is calculated from the stored listings, and the price page shows the date of the most recent listing behind it.
The rules, in order
- Normalize to $/mg. Listed price divided by the stated total peptide mass of the package.
- US dollars, ex-shipping. Shipping, taxes and fees are never included; two stores with different shipping policies compare on product price alone.
- Single vial only. Volume-discount multipacks (for example “10 × 10 mg vials”) are kept out of the headline, lowest and median figures. A bulk rate is a discount, not the price of one vial, and it would drag every “lowest” below what an ordinary single-vial buyer sees. Multipack offers are shown in their own section.
- Regular listed price, not sale prices. We publish the store’s regular listed price. Temporary sale prices are not shown on this site.
- Like for like. Blends are priced on their own pages per mg of total peptide and never mixed into a single compound’s figures. Capsules, tablets and softgels, and topical or cosmetic products, are also left out of injectable-vial comparisons.
- Outliers are not prices. A listing under $1.00 in total is treated as a placeholder, and when a compound has at least five comparable listings, one whose $/mg is more than 20× above or below the compound’s median, or more than 5× below it with no two other stores within 3× of its price (typically bulk raw powder, a mislabelled pack or a placeholder), is excluded from the comparison. It stays a real listing; it is just not ranked against vials.
Lowest, median and “middle half”
The lowest figure is the single cheapest comparable listing. It is a statement about price data, never a recommendation: check each store’s transparency profile before relying on it. The median is the middle listing and is the figure we quote as the typical price, because one mislabelled or bulk listing can distort an average. The middle half is the range between the 25th and 75th percentile of comparable listings. Vendors counts distinct stores with at least one comparable listing.
Dates and history
- As-of dates. Each price page states the date of its most recent listing. Page titles show the month only; the exact day is in the page text.
- 90 days public. The public price chart shows the last 90 days of daily median and lowest $/mg. Days the crawl missed are left out, not filled in, and a trend is only stated when the observed days span at least two weeks. Longer day-by-day history is part of PeptideIQ, our paid product for storefront operators. The monthly price reports keep one median per compound per month and stay up as a record.
- Nightly. The site is rebuilt every night after the data sync; the footer of every page shows the last completed sync.
Rule parameters at a glance
| Rule | Value |
|---|---|
| Placeholder price floor (a listing under this total is not a price) | $1.00 |
| Comparable listings needed before the outlier rule applies | 5 |
| Outlier: more than this multiple above or below the compound’s median | 20× |
| Outlier: below the median by more than this multiple, with no two other stores within 3× | 5× |
| Public day-by-day price history | 90 days |
| Minimum span of observed days before a trend is stated | 14 days |
| Monthly reports: observed days needed to rank a mover | 5 days |
Independence
A vendor’s listing status, trust tier, calculated $/mg, price-sorted placement and rankings are computed the same way for every vendor, and they are never for sale: a vendor cannot pay for a better tier or a better position in a price ranking. If a figure is wrong, submit a correction and we will re-check it against the store’s public page.
What this site does not do
Everything here is for research and price transparency. We sell no peptides and publish no medical content: no dosing, no protocols, no claims of safety or efficacy for human use. Comparisons, including tirzepatide vs semaglutide and retatrutide vs tirzepatide, compare price data only.
The Peptide Index does not list or price anabolic steroids or SARMs, and it does not list stores that sell them.
Keep reading
- Frequently asked questions, including what a trust tier does and does not mean.
- How vendor trust signals are checked, record by record.
- About The Peptide Index.
- Compare $/mg for every compound.
How to cite this page: The Peptide Index (Peptide Price History). “How $/mg works: how we calculate and compare peptide prices.” Methodology version 1.5.1. https://www.peptidepricehistory.com/how-per-mg-works/.