How the TB-500 calculator works
Lyophilized (freeze-dried) powder in a sealed vial, labelled in milligrams. The quick-fill buttons in the calculator are the vial sizes TB-500 is commonly labelled in (2 mg, 5 mg and 10 mg). If yours is different, type it in.
Amounts of TB-500 are usually written in milligrams (mg), so the calculator opens in mg.
Because the name covers two different molecules, check the label for what the vial actually contains. The arithmetic on this page is by weight and works the same either way.
For a field-by-field walkthrough and a guide to syringe types, see the main peptide calculator.
TB-500 concentration table
Each labelled vial size at the same three round water volumes used across this site. It shows how the arithmetic behaves and is not a suggestion of what to use.
| Vial | Water added | Concentration | Each mark holds |
|---|---|---|---|
| 2 mg vial | 1 mL | 2 mg/mL | 0.2 mg per 10 units |
| 2 mg vial | 2 mL | 1 mg/mL | 0.1 mg per 10 units |
| 2 mg vial | 3 mL | 0.67 mg/mL | 0.067 mg per 10 units |
| 5 mg vial | 1 mL | 5 mg/mL | 0.5 mg per 10 units |
| 5 mg vial | 2 mL | 2.5 mg/mL | 0.25 mg per 10 units |
| 5 mg vial | 3 mL | 1.67 mg/mL | 0.167 mg per 10 units |
| 10 mg vial | 1 mL | 10 mg/mL | 1 mg per 10 units |
| 10 mg vial | 2 mL | 5 mg/mL | 0.5 mg per 10 units |
| 10 mg vial | 3 mL | 3.33 mg/mL | 0.333 mg per 10 units |
Every row for a given vial holds the same total. To compare volumes for a specific reading, use the BAC water calculator.
The formula, step by step
The “Try example numbers” button uses one fixed rule on every page: the smallest labelled vial, 2 mL of water, and whatever amount lands on the 10-unit mark. The amount is a by-product of that rule and not a typical or suggested TB-500 dose.
- Concentration: 2 mg ÷ 2 mL = 1 mg/mL.
- The 10-unit mark is 10 ÷ 100 = 0.1 mL, which holds 0.1 × 1 = 0.1 mg.
- Run it forwards to check: 0.1 mg ÷ 1 mg/mL = 0.1 mL, and 0.1 × 100 = 10 units.
TB-500: general reference
General educational reference for research purposes only. None of it is a recommendation, none of it is medical advice, and none of it is used by the calculator, which works only on the numbers you enter.
TB-500 is a synthetic peptide of seven amino acids (Ac-LKKTETQ) that matches residues 17 to 23 of thymosin beta-4, a 43-amino-acid protein found in most human cells. The name is used loosely, and some products sold as TB-500 contain full-length thymosin beta-4 instead.
No pharmacokinetic study of the TB-500 fragment itself has been published, in humans or otherwise. Figures quoted for it online are extrapolations, not measurements.
The human data that exists is for full-length thymosin beta-4. In a 2010 study, healthy volunteers received it intravenously for up to 14 days, and it was cleared from the blood within hours.
Thymosin beta-4 has been taken into clinical trials, but neither it nor TB-500 has been approved as a medicine.
- Class
- Synthetic fragment of thymosin beta-4
- Group
- Thymosins and BPC-157
- Also known as
- Thymosin beta-4 fragment, Ac-LKKTETQ
- Molecular weight
- About 889 Da for the fragment. Full-length thymosin beta-4 is about 4,963 Da.
- Half-life
- Not established. No published study has measured the half-life of TB-500. Full-length thymosin beta-4, a different and much larger molecule, showed a half-life of roughly one to two hours after intravenous dosing in healthy volunteers.
- Regulatory status
- Not approved as a medicine. TB-500 is not approved as a medicine by the FDA, the EMA or any other major regulator. Its position in US pharmacy compounding changed in 2023 and again in 2026 and remains under FDA review, so check the FDA’s current bulk drug substances lists for the present status.
- Status in sport
- Prohibited at all times under the WADA Prohibited List (section S2), which names thymosin beta-4 and its derivatives, including TB-500.
- Labelled vial sizes
- 2 mg, 5 mg and 10 mg
Arithmetic slips to watch for with TB-500
Milligram amounts mean larger draws
TB-500 amounts are usually written in milligrams rather than micrograms. At the same concentration a milligram-scale amount is a far larger volume than a microgram-scale one, so check the result against your syringe. The calculator warns when it will not fit.
Two molecules share one name
A milligram of the seven-amino-acid fragment and a milligram of full-length thymosin beta-4 weigh the same but contain very different numbers of molecules, because the full protein is more than five times heavier. The calculator works by weight only and cannot tell them apart.
A small vial is only a few draws
With a 2 mg vial, “draws per vial” can be a small number. It is simply the vial divided by the amount entered, shown so that a record of what is left stays accurate.
What this page does not do
The calculator performs mathematical conversions only. It does not recommend, suggest or verify any TB-500 dose or schedule, it does not say how much water to add, and it does not say what TB-500 is for, whether it is safe, or whether it is legal where you live. It is not medical advice, diagnosis or treatment, and Peptrack does not sell, supply or endorse any substance.
Always confirm measurements with a licensed healthcare provider or pharmacist. See the full disclaimer.
Sources
- Ruff et al. (2010), single and multiple dose study of intravenous thymosin beta-4 in healthy volunteers, Annals of the New York Academy of Sciences
- BSCG: TB-500 status, risks and bans in sport
- WADA Prohibited List
- FDA: bulk drug substances used in compounding under section 503A
Facts last checked: September 2026. Regulatory status changes, so check the regulator’s own pages for the current position.
