Tirzepatide is the most effective weight-loss peptide with a published Phase 3 trial — SURMOUNT-1 showed up to 22.5% body weight reduction. It's also the most popular research peptide on the market, which means vendor quality varies wildly. A cheap 30mg vial from the wrong source can contain 60% of the labeled dose, or worse, be a different compound entirely.
If you're looking for tirzepatide for sale, quality is everything here. This guide covers what you should actually pay per milligram when you buy tirzepatide, which vial size fits a titration protocol, how to verify a COA for a complex modified peptide, and the vendor red flags that signal counterfeit product. Tirzepatide is a 39-amino-acid dual GIP/GLP-1 agonist with a C20 fatty-acid side chain — synthesis is non-trivial, and quality matters.
This is not a ranked vendor list — for that, see our Best Tirzepatide Vendors comparison. This guide teaches you how to evaluate any vendor yourself.
Understanding Tirzepatide Pricing
Tirzepatide is sold as a lyophilized powder in sealed glass vials. The three factors that move price: vial size (bigger = substantially cheaper per mg), manufacturer sourcing (US-synthesized costs more than overseas-imported), and vendor investment in third-party testing.
Current Market Pricing (2026)
| Vial Size | Typical Price Range | Price Per mg | Best For |
|---|---|---|---|
| 5 mg | $50-55 | $10-10.40/mg | Tolerance testing, single dose trial |
| 10 mg | $44-75 | $4.40-7.50/mg | Short titration (2-4 weeks) |
| 15 mg | $62-110 | $4.13-7.33/mg | Early-stage dosing (2.5 mg/week × 6 weeks) |
| 20 mg | $80-140 | $4-7/mg | Mid-protocol titration |
| 30 mg | $88-200 | $2.93-6.67/mg | Standard — best all-around value |
| 45 mg | $140-240 | $3.11-5.33/mg | Longer protocols, established users |
| 60 mg | $143-300 | $2.38-5/mg | Long-term maintenance, best $/mg |
The pattern is clear: 30mg is the sweet spot — it drops per-mg cost by ~30% versus 10mg while staying within the 28-day stability window at almost any dose. Jumping to 60mg saves another 10-20% per mg but requires confident commitment to a sustained protocol. Our Peptide Price Index Q1 2026 put tirzepatide as the most-tracked peptide in the dataset (218 observations, 7 vendors, median $5.50/mg) with the lowest stockout rate of any deep-dive peptide at 3.2%.
Vial-count math depends on the protocol you're running, so cross-check your tirzepatide dosage before placing the order — buying for a 2.5 mg/week titration looks very different from a 10 mg/week maintenance protocol.
Cheapest single-vial option: Ascension Peptides' 50% off drops tirzepatide 30mg to $59 ($1.97/mg effective) — the lowest effective price we track for buying one vial. Get the code →
Cost Per Week at Common Doses
| Weekly Dose | Monthly Cost (10mg vial) | Monthly Cost (30mg vial) | Savings |
|---|---|---|---|
| 2.5 mg/week (starter) | $44-75/month | $29-67/month | ~25% |
| 5 mg/week (standard) | $88-150/month | $59-133/month | ~25% |
| 10 mg/week (high) | $176-300/month | $117-267/month | ~25% |
For current vendor-specific pricing with exact $/mg breakdowns, see our Best Tirzepatide Vendors comparison.
How to Verify Tirzepatide Quality
Tirzepatide is not a simple peptide. It's a 39-amino-acid dual agonist with two non-coded aminoisobutyric acid (Aib) residues, an amidated C-terminus, and a C20 fatty-diacid side chain connected via a PEG linker to the lysine at position 20. Synthesis is expensive and error-prone. If a vendor isn't showing you a recent COA, you have no idea what's in the vial.
What a COA (Certificate of Analysis) Should Include
Identity Confirmation
- Mass spectrometry confirming the correct molecular weight (4,813.52 Da for tirzepatide)
- Amino acid sequence verification with the Aib modifications at positions 2 and 13
- Confirmation of the C20 fatty acid conjugation
Purity Testing
- HPLC purity — look for 98%+ purity
- The chromatogram should show a single dominant peak with minimal truncated-sequence impurities
Contamination Testing
- Endotoxin levels (bacterial contamination)
- Residual solvent analysis (acetonitrile, TFA)
- Heavy metals screening
How to Verify a COA Is Legitimate
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Check the testing lab — Reputable labs include Janoshik Analytical, MZ Biolabs, and Colmaric Analyticals. Avoid vendors who only show "in-house" testing.
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Verify on the lab's website — Janoshik COAs have a task number you can look up directly at janoshik.com. If the vendor won't provide a verifiable task number, that's a red flag.
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Check the date — COAs should be recent (within 6 months). Old COAs may not represent the current batch.
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Match the batch — The batch/lot number on the COA should match what's printed on your vial.
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Look for the original PDF — Screenshots are easier to fake than full PDFs with lab letterhead and signatures.
Red Flags to Avoid
- No COA available — for a peptide this complex, zero testing is a hard pass
- Only in-house testing — self-reported purity numbers are meaningless
- Prices below $2/mg across all sizes — synthesis costs make this implausible without corner-cutting
- No contact information — legitimate vendors have real customer service
- Cryptocurrency only — good vendors accept crypto but also standard payment rails
- No return or reship policy — reputable vendors stand behind their products
