Where to buy Tirzepatide Peptide: sizes, price per mg and how to verify the lot

What "tirzepatide peptide" names, and what it does not

Tirzepatide is a 39-residue synthetic peptide built on the GIP sequence, with two α-aminoisobutyric acid (Aib) residues at positions 2 and 13 and a C20 fatty diacid attached through a linker to the lysine at position 20. Eli Lilly developed it under the code LY3298176 and the papers cited at the foot of this page describe it as a dual agonist at the GIP and GLP-1 receptors. Listings spell it tirzepatide, tirzepatide peptide, LY3298176 and, in the abbreviated form that is a liability in any record, "tirz". They are one molecule, formula C225H348N48O68, average mass 4,813.5 Da.

The point a buyer has to hold onto is that the approved medicines containing tirzepatide are not this product. Mounjaro and Zepbound are drug products made under an approval, with a manufacturing process, a specification and a release test that no research vial has been through. A research vial of tirzepatide is a synthetic peptide with the same sequence sold as laboratory material, and the only thing that stands behind it is the certificate for its lot. Sellers who borrow the drug's reputation for the powder are selling a name; the certificate is what is actually in the vial.

The fatty diacid is what makes this compound harder to make and harder to test than a plain peptide. The linker and the C20 chain have to be attached at the right lysine, and the molecule is large enough that its mass spectrum is a cluster of multiply charged ions that must be deconvoluted to give one mass. A laboratory that reports 4,813 Da with the spectrum shown has done that work; a certificate that prints "conforms" has not.

The reference point for identity is public. PubChem lists Tirzepatide as CID 166567236 with molecular formula C225H348N48O68, an average molecular weight of 4813 Da and a monoisotopic mass of 4810.525 Da. Those are the numbers a mass spectrometer is checked against, and the number a certificate must print beside the observed mass.

In plain terms: A peptide that works on the GIP and GLP-1 receptors at the same time. What is sold here is a research chemical, not a drug product. Listing it is not an approval, and not a claim that it is equivalent to, as safe as, or a fit substitute for any approved medicine.

Tirzepatide for sale: sizes and price per mg

LabFirst lists Tirzepatide in 14 sizes (5mg, 10mg, 15mg, 20mg, 30mg, 40mg, 50mg, 60mg, 70mg, 80mg, 90mg, 100mg, 110mg, 120mg) from $50 to $260, priced per vial with the per-mg figure beside it so sizes can be compared without arithmetic. Per mg, the 20mg vial is the cheapest today at $6.25 and the 5mg the dearest at $10, which is the reverse of the usual shape; the table below is the arithmetic, and the per-mg column, not the vial price, is the one to compare.

The volume tiers are per size, not per basket: ten vials of one size take 10% off that line and twenty take 15%, and mixed sizes do not combine. Shipping is a flat $15 on orders under $200 and free from $200, within the United States only, with same-day dispatch on orders placed before 12 PM Pacific on a business day. The cost per mg tool runs the same comparison across any two listings, ours or anyone else's.

Tirzepatide is expensive to make and the price shows it: a long synthesis, a lipidation step, a purification that has to separate near-identical impurities, and a large molecule to characterise. That is why LabFirst lists it in fourteen sizes from 5 mg to 120 mg and why the per-milligram figure falls so far across the range; the vial, fill and laboratory run are a fixed cost that a 100 mg vial spreads over twenty times the mass of a 5 mg one. For a laboratory that will use the material, the larger vial is the cheaper one by a wide margin; for one qualifying a lot, the 5 mg vial is the sensible first purchase.

Price is also where the des-diacid trap shows. A tirzepatide listing priced like a plain 39-residue peptide, well under the market, is often exactly that: the sequence without its C20 side chain, which costs a fraction to make and weighs about 745 Da less. It is not a bargain, it is a different compound. The certificate's observed mass is the only defence, which is why the volume discount on this page is per size and steady, and why the lot on the vial is whatever the certificate index says on the day.

The certificate a Tirzepatide lot must carry

Three tests answer three different questions, and a certificate of analysis for Tirzepatide is only complete when it carries all three for the exact lot on the vial. Identity is settled by mass spectrometry, and the number to look for on a Tirzepatide certificate is 4810.525 Da monoisotopic (or 4813 Da average, if the laboratory reports the deconvoluted average mass). The observed mass should sit within the instrument's stated tolerance of that figure, and the certificate should print both the theoretical and the observed value, not just a tick.

Purity is a separate question, answered by HPLC: how much of what came off the column was the compound. The figure is only interpretable with its method beside it (column, gradient, detection wavelength) and a date, which is what ICH Q2(R2) means when it asks that an analytical procedure be shown fit for its purpose. A percentage with no method and no date is a number somebody typed, and a certificate that carries every test but for a different lot number than the vial is the most common failure of all and the easiest to catch. Net content is the third test and the one most often missing: the milligrams of Tirzepatide actually in the vial, measured, against the size printed on the label.

Identity for tirzepatide is a deconvoluted mass within a fraction of a dalton of 4,810.52 Da monoisotopic or 4,813.5 Da average, and the certificate should say which it reports. The raw electrospray spectrum shows charge states from about 4+ to 8+ (m/z 1,203, 963, 803, 688 and so on), and a laboratory that prints those alongside the deconvoluted value has shown its work. A mass about 14 Da low can be an Aib-to-Ala substitution; a mass roughly 745 Da low is the peptide without its whole side chain (the C20 diacid, the glutamate and the two linker units), a different and much cheaper molecule that some factories ship under the same name, and about 325 Da low is the linker without its acyl chain.

Purity by HPLC on a molecule this size is a question of resolution: the des-diacid form, deamidated forms and truncated sequences all run near the main peak, so the chromatogram with its column, gradient and wavelength is the evidence, not the percentage. Net content is the third line and, for tirzepatide, the one most worth paying for: at these prices per milligram, a 10 mg vial that holds 8 mg of peptide plus counter-ion and water is a 20% overcharge that only quantitative HPLC or amino acid analysis can reveal. Ask for net content in milligrams of peptide, and read the counter-ion (acetate or trifluoroacetate) beside it.

Where to buy Tirzepatide: five checks before you order from anyone

Every seller of tirzepatide peptide says "third-party tested". The phrase costs nothing. These five checks take about four minutes per listing and separate a tested lot from a tested-sounding one.

1. The lot on the vial is the lot on the certificate. Read the printed lot number, then open the certificate and match it. A certificate for "Tirzepatide" with no lot, or a lot that does not match, describes some other vial.
2. The laboratory is named and has its own lookup. The report should come from a laboratory the seller does not own, with a search code you can enter on the laboratory's own site. LabFirst lots are tested by Freedom Diagnostics and looked up by accession number; anything that can only be verified on the seller's own page has not been verified.
3. The theoretical mass is printed, and it is the right one. For Tirzepatide that is 4810.525 Da monoisotopic; a certificate that prints a different figure has either measured a different molecule or copied a template.
4. Purity has a method and a date. An HPLC percentage should name the method and the run date. A figure that reads "99%+" with neither, or one date reused across every product a seller lists, is decoration.
5. Net content is stated in milligrams. The label size is a claim; the certificate's net content is the measurement. If the certificate has no net content line, the purity figure describes the powder, not the vial, and the price per mg you calculated is fiction.

How listings for Tirzepatide specifically mislead:

• A price far below the market for a 39-residue lipidated peptide. The cheap version is usually the sequence without its C20 side chain, about 745 Da lighter on the certificate and a different compound.
• "Same as Mounjaro" or "same as Zepbound". Those are approved drug products with a release specification; a research vial has a lot certificate and nothing else, and no equivalence is claimed or possible.
• A certificate with a single rounded mass and no spectrum. A 4,813 Da molecule gives a cluster of charge states that must be deconvoluted; a bare number with no trace could have come from anywhere.
• A 10 mg label with no net content line. At tirzepatide prices the difference between 10 mg of powder and 10 mg of peptide is a fifth of the money; only quantitative content settles it.

How to verify a LabFirst Tirzepatide lot

The Tirzepatide sizes in stock today carry lots LF-2608-29 and PO-1001-TR20. Lot LF-2608-29 is at Freedom Diagnostics on accession FD-2026-05716 for identity, purity and net content. Until the report is attached the product page says "pending verification" against that lot and makes no purity claim; the price stands and the report goes live the day it arrives, on the page, at /coa/, and inside the receipt and packing slip for every order of that lot.

Verification runs through the laboratory, not through us. Open the certificate index, find the lot, and use the accession number on the Freedom Diagnostics lookup page; the report you see there is the laboratory's copy, not ours. Each lot also carries a Finnrick verify link, and every receipt and packing slip states that a customer may submit a sealed vial to Finnrick's free testing programme with the order as proof of purchase, so the brand's public record is built from vials we did not choose.

The product page reads the live stock feed on load (stock, lot and certificate state for every size), so what you see when you order is what ships. The lot is printed on the label and encoded in the QR patch on its right-hand side; scanning it opens that lot's record.

Storage and shipping for Tirzepatide

Lyophilised tirzepatide is a stable white cake when sealed at 2 to 8 C out of light; the fatty diacid makes it somewhat more prone to aggregation than a plain peptide once in solution, and the asparagine and glutamine residues can deamidate slowly, so a prepared solution is dated, kept cold and used within the laboratory's own stability record rather than a label's. The sealed cake's enemy is water: a vial opened in humid air and re-closed takes on moisture and no longer weighs what the label says, so open a vial once, for its purpose, and never re-seal one for storage. Freezing the dry cake is unnecessary; freeze-thaw of a solution is what causes trouble.

Orders ship within the United States, flat $15 under $200 and free above it, same day when placed before 12 PM Pacific on a business day, and the shipping page states the cutoff, the carriers and what is and is not promised.

The record a laboratory keeps on arrival is what makes the certificate usable later, and it is short:

• the lot number as printed on the vial, and the certificate's accession or search code beside it;
• the date received and the condition of the seal;
• the storage location and temperature it went into;
• the number of vials, and later the date each one was opened and by whom.

A Tirzepatide vial with that record behind it can be traced from the bench to the laboratory report in one step; without it, the certificate is a document about a vial that can no longer be identified.

Regulatory status, and what this page is not

Tirzepatide is the active ingredient of two approved medicines, Mounjaro (2022) and Zepbound (2023), both from Eli Lilly. That approval belongs to those products and their manufacturing, and it confers nothing on a research vial: the material sold here is not made under it, is not tested to its specification and is offered as laboratory material only, with no claim that it is equivalent to, as pure as, or a substitute for any medicine. The FDA's drug shortage listing for tirzepatide ended in December 2024, which is why compounded versions largely disappeared from pharmacies; that too concerns pharmacies and drug products, not research powder. There is no USP monograph for the bulk peptide that a research lot could claim to meet.

FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. LabFirst sells Tirzepatide to laboratories and researchers as material for in-vitro work, gives no guidance on use, and ships only against that understanding. Nothing on this page or on the product page describes preparing or administering anything.

What is Tirzepatide studied for?

Published research on Tirzepatide investigates the areas below — which is a different question from what Tirzepatide will do for anyone, a claim about a living system that nothing on this site is sold for.

What it is. A peptide that works on the GIP and GLP-1 receptors at the same time.

What the research looks at. There is a large published clinical record: how it behaves at the receptors, how the body handles it, and the measurements its sponsor registered its trials to take. Approved medicines containing it exist under their own brand names.

How it is thought to work. It switches on both the GIP receptor and the GLP-1 receptor. Working on two rather than one is the design feature that separates it from the GLP-1-only drugs.

What is not established. What is sold here is a research chemical, not a drug product. Listing it is not an approval, and not a claim that it is equivalent to, as safe as, or a fit substitute for any approved medicine.

The full record, including the certificate for the lot in stock, is on the Tirzepatide product page.

Common questions

Sources

• PubChem, Tirzepatide, CID 166567236. Public record for the molecular formula (C225H348N48O68), average molecular weight (4813 Da) and monoisotopic mass (4810.525 Da) quoted here as the identity reference.
• Coskun and colleagues, LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: from discovery to clinical proof of concept, Molecular Metabolism 2018. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• Willard and colleagues, Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist, JCI Insight 2020. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• ICH Q2(R2), Validation of Analytical Procedures (2023) 2023-11. Why a purity figure is only interpretable with its method, and what "fit for purpose" means for the HPLC and mass spectrometry results a certificate reports.
• Freedom Diagnostics, certificate lookup by accession number. The laboratory-side lookup a LabFirst lot is verified on; the report there is the laboratory copy, not ours.
• Finnrick, verify a vendor or lot. Independent verification page linked from every LabFirst lot; customers may submit sealed vials with their order as proof of purchase.