TB-500 is the active 17-23 amino acid fragment of thymosin beta-4 — the 889 Da synthetic heptapeptide (Ac-LKKTETQ) that captures the LKKTET actin-binding motif at a fraction of full TB-4's cost. Pricing on the research market ranges from $4/mg to $40/mg for essentially the same molecule, and vendor quality matters more than ever because a mislabeled full-TB-4 product can be 5× the cost per mg.
This guide covers what you should actually pay, which vial size fits the standard 500 mcg/day protocol, how to verify a COA for the heptapeptide specifically (not full TB-4), and vendor red flags. TB-500 is also the primary pair for BPC-157 in the wolverine stack, so factoring both into your purchase makes sense.
This is not a ranked vendor list — for that, see our Best TB-500 Vendors comparison. This guide teaches you how to evaluate any vendor yourself.
Understanding TB-500 Pricing
TB-500 is sold as a lyophilized powder in sealed glass vials. It's a short 7-amino-acid peptide and cheap to synthesize correctly — there's no excuse for a legitimate vendor to skip testing. The three factors that move price: vial size, manufacturer sourcing, and whether the vendor pays for third-party COAs.
Current Market Pricing (2026)
5 mg
$29-75
$5.80-15/mg
Short 10-day trial, tolerance testing
10 mg
$44-110
$4.40-11/mg
Standard 500 mcg/day — best all-around
The pattern is clear: 10mg is the sweet spot for virtually every TB-500 protocol. The 5mg vial exists mainly as a low-commitment trial size — it costs 20-40% more per mg and doesn't align cleanly with the typical 20-28 day loading phases.
Cheapest single-vial option: Ion Peptide's 15% off drops the 10mg vial to $41.65 ($4.17/mg effective) — the lowest effective price we track for buying one vial. Get the code →
Cost Per Week at Common Doses
2 mg/week (loading)
$23-60/month
$18-44/month
~25%
3.5 mg/week (500 mcg/day)
$41-105/month
$31-77/month
5 mg/week (aggressive)
$58-150/month
$44-110/month
For current vendor-specific pricing with exact $/mg breakdowns, see our Best TB-500 Vendors comparison.
How to Verify TB-500 Quality
TB-500 is the synthetic heptapeptide Ac-LKKTETQ — the N-acetylated active fragment corresponding to residues 17-23 of endogenous thymosin beta-4. Its molecular weight is 889 Da. Full-length TB-4 is 43 amino acids at 4,921 Da. These are different molecules, and some vendors blur the line — either selling full TB-4 as "TB-500" (cheating you out of 5× the peptide mass) or claiming "TB-500" that's actually a non-acetylated fragment with reduced stability.
What a COA (Certificate of Analysis) Should Include
Identity Confirmation
Mass spectrometry confirming the correct molecular weight (889 Da for TB-500)
Amino acid sequence verification matching Ac-LKKTETQ
Confirmation of N-terminal acetylation — critical for TB-500 stability
Purity Testing
HPLC purity — look for 98%+ purity
The chromatogram should show a single dominant peak with minimal non-acetylated or truncated impurities
Contamination Testing
Endotoxin levels (bacterial contamination)
Residual solvent analysis (acetonitrile, TFA)
Heavy metals screening
How to Verify a COA Is Legitimate
Check the testing lab — Reputable labs include Janoshik Analytical, MZ Biolabs, and Colmaric Analyticals. Avoid vendors who only show "in-house" testing.
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.
Check the date — COAs should be recent (within 6 months).
Match the batch — The batch/lot number on the COA should match what's printed on your vial.
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 — any vendor unwilling to provide testing results is not worth the risk
Only in-house testing — self-reported purity numbers are meaningless
MW shown as ~4,921 Da — that's full TB-4, not TB-500. Real TB-500 is 889 Da
Missing acetylation confirmation — non-acetylated fragments degrade faster and have reduced bioactivity
Prices well below $4/mg — implausible for correctly-synthesized, N-acetylated TB-500
No return or reship policy — reputable vendors stand behind their products