Methodology

Price per milligram

Four price figures are kept separate.

• Input: comparable mass (mg) = mass per unit (mg) × unit count.
• $/mg = list price ÷ comparable mass.
• Effective $/mg = effective price ÷ comparable mass, naming its discount: "Includes verified code. Shipping, duties and taxes excluded."
• Cost to 10 mg = effective price × the fewest whole listings that reach 10 mg.
• Destination subtotal = effective price + shipping + duties + taxes, shown only once every part is known. Nothing is guessed.
• Shipping comes from each vendor's own shipping policy, read once a week, and shows only what the policy states plainly; it never changes a price or $/mg.

Products with no $/mg

Some products show no $/mg and state why.

• Blends: never compared with a single compound.
• Products sold in IU or by liquid volume, and forms we do not class: no $/mg. Capsules need the mg in each capsule and the capsule count; sprays need the mg in the bottle.
• Products sold with other products, such as diluent, syringes or a starter kit: the compound is named, with no $/mg.
• Single vials and multi-vial packs never share a line: a single vial of any size is retail, a multi-vial pack is bulk.
• Forms never share a line either. The default everywhere is the lyophilized vial: dry powder, not yet mixed. Solutions (pre-mixed or reconstituted liquid), raw powder, capsules and sprays are each compared only with their own form.

Statistics for vendors listed

Each compound has one chart in $/mg across every vial size. Each other form, size and pack type has its own chart one step away. Each shows "N vendors listed."

The median (the middle price) appears only with three or more vendors listed. Below that, the page leads with lowest listed $/mg and says why: a median of one or two prices only restates them. Lowest listed $/mg shows at any count. One vendor reads "1 vendor listed · market = this vendor." Any statistic describes the vendors listed and nothing wider. The data feed also gives the mean and the mode, in $0.05 bins, at any count, with the number of vendors beside them.

Charts up to three months long plot one point a day; a year or more, one point a week (weeks start Monday, UTC). A vendor read once a week counts on the days between its reads at its last price.

List and effective series never mix. Gaps in price history stay gaps.

• Median $/mg.
• Lowest listed $/mg.
• Effective low: the lowest listed effective $/mg.

Peptide Price Index

The index follows 24 common peptides, each in one vial size sold as a single vial; no other form counts. A compound's base is its lowest effective $/mg in that size in the first week with at least one listing in stock, counting from the week of 28 Sep 2026 or the week the compound joined, whichever is later. Only weeks whose figures are final count. A base is set once and never changed. The base week named on the index page is the earliest of these.

Each day or week, a compound's value is its lowest effective $/mg in that size over every listing read in the period, in stock or not, divided by its base and multiplied by 1,000. So a base or a value can come from a listing that was out of stock when read. A compound's value in its base week is 1,000; 700 means its lowest $/mg is 30% below its base. A compound counts only from its base week, and only on days or weeks with at least one listing in stock in that size. Each day or week, the index moves by the mean move of the compounds counted in both that period and the one before, each compound weighted equally, and the page says how many were counted. While the same compounds are counted, that is the mean of their values times a fixed link, so the index can differ from the plain mean of the values shown. A category index moves the same way with its members. So when a compound joins or leaves the basket, or is not counted for a day or week, the index and its category do not jump; only the compound's later price moves count.

The Lowest $/mg on the index compounds board is a different figure: the lowest current listing in that size, as the compound's page shows it, with stale prices only when nothing fresher exists.

Freshness

Each number shows its freshness state and last successful check. A failed check keeps the last good value, shown for example as "Last successful price check 2 days ago." A source disabled under a hard stop follows the rule on the Sources page.

• recent: checked in the last 6 hours
• checked: 6 hours to 14 days ago
• stale: 14 days or more without a successful check
• Check failed: the latest check failed or was stopped; the last good price stays

Order

Rows sort by when we last checked the price, most recent first, to the hour; prices checked in the same hour sort by the lowest price a buyer gets through this site. Where we hold a discount code with a vendor, that price includes it; the code is named only when you click out to the vendor. Vendor, List, Effective, $/mg, 30 days and Checked can be sorted; under any sort a stale price sorts last, and so does a listing with no value in that column.

• Sponsorship: zero weight. Any paid placement sits outside the sorted list, labeled "Sponsored · Paid placement · does not affect ranking or scores."
• Commission: zero weight. What we earn is never read by the sort. Any affiliate link is disclosed next to its outbound button: "Affiliate link. Commission does not affect ranking or scores."
• Who built the site: zero weight.

Sources and corrections

Prices come only from sources the owner marks as allowed, normally a vendor feed or a permitted catalog URL. Crawling is the exception and stops at a login wall, CAPTCHA, robots disallow, repeated 403 or cease-and-desist. It never uses IP rotation or CAPTCHA solving. A raw copy is saved before parsing, never altered, and kept for 30 days; every price read from it is kept permanently. Vendors will be able to dispute their record, but not edit or delete another party's observation, and corrections will leave an audit trail. See Sources.

Changes to this method

Each change to this method will be dated and signed off by the owner, CHRSMA Co.