Educational reference only — not medical advice. This calculator does maths only and does not recommend any dose. Always confirm your dose and preparation with a licensed healthcare provider or pharmacist.
Reconstitution Calculator
Results update live as you type. Your dose must come from your prescription or provider — this tool never suggests one.
Printed on the vial label — the total powder in the vial.
The volume of bacteriostatic water you mix into the vial.
Enter the dose exactly as given to you. 1 mg = 1,000 mcg.
U-100 syringes: 100 units = 1 mL, whatever the barrel size.
Nothing you type leaves this page — the calculation runs entirely in your browser. Educational reference only, not medical advice.
TB-500 is one of those names that sounds simple until you look closely. The vial in front of you might contain the molecule the name usually means, or it might contain something else entirely — and the maths only works if you know which one you have. This page starts with that warning, then does the arithmetic.
What is TB-500?
TB-500 is a synthetic 7-amino-acid fragment (Ac-LKKTETQ) taken from residues 17–23 of thymosin beta-4, a 43-amino-acid protein found in almost all human and animal cells. Here is the catch: the name is used loosely in the market. The FDA and PubChem use “TB-500” for the 7-residue fragment, but many vendors’ certificates of analysis list the identity as full 43-residue thymosin beta-4. Those two molecules differ more than five-fold in mass, so before you trust any calculation, check the identity line on your lot’s certificate of analysis.
It is sold as a freeze-dried powder for laboratory research. It is not FDA-approved for any use, no approved drug contains it, and the FDA has said it has not identified any human exposure data for the TB-500 fragment (human trials in this area used full-length thymosin beta-4, not the fragment). Like BPC-157, it went through the same 2026 compounding review — an advisory vote of 8–6 to recommend adding it to the 503A bulks list, non-binding, no final rule. WADA lists it under class S2 (thymosin beta-4 and its derivatives, including TB-500), prohibited at all times.
The vial maths.
Standard TB-500 vials are 5 mg and 10 mg. The calculation is the same as for any peptide: concentration first, then volume, then units.
Worked example — 10 mg vial, 2 mL of BAC water, example dose 500 mcg:
- Concentration: (10 × 1,000) ÷ 2 = 5,000 mcg/mL
- Each unit holds 5,000 ÷ 100 = 50 mcg
- Units for the example dose: 500 ÷ 50 = 10 units (0.1 mL)
- Doses in the vial: 10,000 ÷ 500 = 20 doses
With a 5 mg vial and the same 2 mL of water, the concentration is 2,500 mcg/mL and the same example dose takes 20 units instead of 10. Always read the milligrams printed on your own vial — never assume a standard size.
Storage (commonly cited):
Unmixed vial at −20 °C for long-term storage (2–8 °C for short periods), protected from light. Once mixed, refrigerate at 2–8 °C and do not freeze. Sources commonly cite around 28 days (some say 14–28 days, some 2–4 weeks) — a planning figure, not a measured guarantee for this fragment.
FAQs
How do I calculate syringe units for TB-500?
Concentration = vial mg × 1,000 ÷ water mL. A 5 mg vial in 2 mL is 2,500 mcg/mL, so one unit holds 25 mcg and your units = your dose in mcg ÷ 25. Use the calculator above with your own vial and dose.
My TB-500 vial is 10 mg, not 5 mg. What changes?
At the same water volume the concentration doubles: 10 mg in 2 mL is 5,000 mcg/mL, so each unit holds 50 mcg and the same dose takes half as many units.
How do I know what is actually in my vial?
Check the certificate of analysis for your lot. The product name alone cannot tell you whether you have the 7-residue fragment or full thymosin beta-4 — and the two are not interchangeable for any purpose, including the maths, because their masses differ so much.
Is TB-500 approved?
No. It is not FDA-approved for any use and is sold as a research chemical.
Related calculators
See also the BPC-157 Calculator and the Peptide Calculator home page.
Educational reference only — not medical advice. This calculator does maths only and does not recommend any dose. Always confirm your dose and preparation with a licensed healthcare provider or pharmacist.