What is thymosin beta-4 (TB-4)?
Thymosin beta 4 reconstitution is about how BAC water, the powder in the vial and a U-100 syringe relate, and that is what this page calculates. Thymosin beta-4 is a small protein of 43 amino acids that occurs naturally in many cells and tissues. It belongs to the beta-thymosin family and is best known in laboratory science as a protein that binds actin, one of the main structural proteins inside cells. Labels abbreviate it as TB-4, TB4 or Tβ4.
Research vials labeled thymosin beta-4 are described by sellers as the full 43-amino-acid sequence. This page makes no statement about what TB-4 does in the body; it covers the arithmetic only.
TB-4 vs TB-500: why the names differ
TB-4 and TB-500 are often treated as the same thing, but the names are not interchangeable. Thymosin beta-4 is the name of the natural 43-amino-acid protein. “TB-500” is a name used by sellers, not a scientific name, and it is commonly applied to a shorter synthetic peptide based on one region of thymosin beta-4 rather than the whole protein. Some vendors, however, use TB-500 and thymosin beta-4 loosely on the same label.
The practical rule is simple: the wording and mg on your own vial are what count. The math is identical for both, since concentration depends only on mg and water volume. If your vial is labeled TB-500, the TB-500 calculator covers that product; this page covers vials labeled thymosin beta-4 or TB-4.
How much BAC water for a thymosin beta-4 vial?
Research vials are usually labeled 2 mg, thymosin beta-4 5mg or 10mg of freeze-dried powder. The mg in the vial is fixed; the volume of bacteriostatic water you add sets the concentration. The chart shows micrograms per unit on a U-100 syringe at common water volumes.
| BAC water | 2 mg vial | 5 mg vial | 10 mg vial |
|---|---|---|---|
| 1 mL | 20 mcg/unit 2 mg/mL | 50 mcg/unit 5 mg/mL | 100 mcg/unit 10 mg/mL |
| 2 mL | 10 mcg/unit 1 mg/mL | 25 mcg/unit 2.5 mg/mL | 50 mcg/unit 5 mg/mL |
| 3 mL | 6.67 mcg/unit 0.667 mg/mL | 16.67 mcg/unit 1.667 mg/mL | 33.33 mcg/unit 3.333 mg/mL |
| 5 mL | 4 mcg/unit 0.4 mg/mL | 10 mcg/unit 1 mg/mL | 20 mcg/unit 2 mg/mL |
Each cell shows mcg per unit on a U-100 syringe (100 units = 1 mL) and the resulting concentration.
Read across a row to compare vial sizes at the same volume, or down a column to see how the same vial thins out as water is added. Each cell is vial mg × 1,000 ÷ (water mL × 100). There is no single correct volume. The BAC water to peptide ratio guide explains the pattern.
Worked example: thymosin beta-4 5mg in syringe units
The calculator runs three steps. Vial mg ÷ water mL gives the concentration. The amount you enter ÷ that concentration gives the volume in mL. Volume × 100 gives U-100 units. For example, if the amount you already have is 1 mg, and a 5 mg thymosin beta-4 vial is mixed with 2 mL of BAC water:
The math: 5 mg ÷ 2 mL = 2.5 mg/mL (2,500 mcg/mL), which is 25 mcg per unit. 1 mg ÷ 2,500 mcg/mL = 0.4 mL = 40 units on a U-100 syringe.
That amount is an arbitrary figure picked because it comes out clean. It is not a suggestion. The same method works for the 2 mg and 10 mg sizes; only the concentration changes. Keep everything in one unit before dividing: 1 mg = 1,000 mcg. The mg to mcg conversion guide has a quick reference.
What the TB-4 calculator does and doesn’t do
The calculator answers one question: how many units on a U-100 syringe line up with an amount you already have, for your vial size and water volume. It does not choose an amount, a schedule or a frequency, and it cannot tell whether a vial holds the full protein or a shorter fragment sold under a similar name. The same limits apply to every calculator on this site. Those questions belong to the product labeling and a qualified professional.
Units are the same size on every U-100 syringe: 100 units = 1 mL and 1 unit = 0.01 mL. If a result looks wrong, you can check the calculator math by hand.
Thymosin beta-4 reconstitution notes and status
Supplier instructions vary, so the label comes first. Some suppliers specify bacteriostatic water; others list sterile water. Because TB-4 is larger than most short research peptides, some product sheets note that it may take a little longer to dissolve and advise gentle swirling rather than shaking. Many list refrigeration after mixing. Whatever volume you use, enter that exact figure in the calculator. General steps are in the peptide reconstitution guide.
Thymosin beta-4 is not an FDA-approved drug, and vials sold online are labeled for research use only. Because TB-4 and TB-500 names are used inconsistently, a correct calculation cannot confirm identity, purity, sterility or stability; the result is only as good as the label.
Thymosin Beta-4 (TB-4) FAQ
How much BAC water do you add to a thymosin beta-4 5mg vial?
There is no single required volume. The chart shows how 1, 2, 3 and 5 mL change the mcg per unit. Follow the product labeling for the diluent and volume, then enter the volume you used.
What is the difference between TB-4 and TB-500?
Thymosin beta-4 is the natural 43-amino-acid protein. TB-500 is a seller’s name commonly applied to a shorter synthetic peptide based on part of it, though some labels use the names loosely.
Does the calculator work the same for TB-4 and TB-500?
Yes. Concentration depends only on the mg on the label and the water you add, so the math is identical. The label on your vial tells you which product you have.
Does this page give a thymosin beta-4 dose?
No. It converts an amount you already have into mL and U-100 syringe units for your vial and water volume. It does not recommend a dose, schedule or frequency.
Is thymosin beta-4 FDA-approved?
No. Thymosin beta-4 is not an FDA-approved drug, and vials sold online are labeled for research use only.