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TB-500 Dosage Calculator: Units Per Dose

Enter the milligrams in your TB-500 vial, the milliliters of bacteriostatic water you added and the dose on your prescription. You get the concentration after mixing, the volume per dose, the units on a U-100 insulin syringe and the number of full doses in the vial. It is arithmetic on a dose a clinician chose, not a dose suggestion.

  • Calculator
  • About 3 min
  • Standard reconstitution arithmetic (Boyer, Math for Nurses)
  • Runs in your browser, nothing is sent
  • Medical review: Medical review pending
Open the calculator

What this calculator works out

TB-500 prescriptions are usually written in milligrams while the syringe reads in units, and the vials come in several strengths. The same three steps of arithmetic connect them, and the most common error is a factor of 1,000 between mg and mcg.

  1. 1

    Concentration after mixing

    The vial's milligrams times 1,000, divided by the milliliters of water you added, in mcg/mL. A 5 mg vial with 1 mL holds 5,000 mcg/mL; with 2 mL it holds 2,500 mcg/mL and every draw doubles in size.

  2. 2

    Volume and syringe units per dose

    Prescribed micrograms divided by the concentration gives milliliters; milliliters times 100 gives units on a U-100 insulin syringe. A 2 mg dose at 2,500 mcg/mL is 0.8 mL, or 80 units, which is most of a 1 mL syringe.

  3. 3

    Full doses in the vial

    How many complete doses the vial holds at this prescription, rounded down. With TB-500, doses are often a large share of the vial, so this number is frequently 2 or 3 and matters for how many vials a prescription needs.

How this compares with a typical online quiz

FeatureTypical free quizRegenerated.com
Takes the dose from your prescription, not a chartOften shows a doseYes, only the prescribed dose is entered
Handles mg prescriptionsSometimesYes, the help text shows the mg to mcg step
Doses per vialRarelyYes, rounded down to full doses
FDA compounding status statedNoYes, with each FDA page's own date and our check date
Sells or links to peptidesOftenNever
Answers sent to a serverOftenNever; scored in your browser, counts-only events

What TB-500 is and where it stands with the FDA

Thymosin beta-4 is a small protein of 43 amino acids found in almost every human cell, where it binds actin and helps cells move and repair. TB-500 is the trade-style name for a synthetic version of it, usually the short active fragment (amino acids 17 to 23) and sometimes the full peptide. Animal studies from the early 2000s showed faster wound closure and some heart muscle repair after injury, which is where the interest in injection for tendon, ligament and muscle recovery comes from. Human trials of injectable thymosin beta-4 reached early phases for heart disease and wound healing but none finished and none led to approval; the eye-drop form for corneal disease is the only version still in late-stage trials.

TB-500 is not FDA approved for any use. On September 29, 2023, the FDA placed thymosin beta-4 fragment (LKKTETQ), the peptide sold as TB-500, in category 2 of the bulk drug substances nominated for compounding under section 503A, citing significant safety concerns including the lack of human safety data and the risk of immune reactions. The nomination was then withdrawn by the nominator. The FDA's 503A category list updated April 22, 2026 removed it from category 2 on exactly that ground, the list updated May 14, 2026 does not carry it in any category, and the agency's safety-risk page, current as of April 22, 2026, lists it among the withdrawn nominations with the same safety concerns still set out. We checked both on October 8, 2026. A withdrawn nomination is a decision by whoever nominated the substance, not an FDA finding that the substance is safe, and it did not make TB-500 compoundable: section 503A lets a pharmacy compound from a bulk substance only if that substance has a USP or NF monograph, is a component of an FDA-approved drug product, or appears on the 503A bulks list, and TB-500 meets none of the three, so a US pharmacy has no route under 503A to compound it from bulk. The FDA consulted its Pharmacy Compounding Advisory Committee on July 23, 2026 on whether TB-500-related bulk substances should go on that list, and the agency's own briefing document for that meeting proposed that TB-500 (free base) and TB-500 acetate not be included; the committee's advice is non-binding, and as of October 8, 2026 the FDA had not acted on it. Thymosin beta-4 and its derivatives, TB-500 among them, are also named under section S2.3 (growth factors) of the World Anti-Doping Agency Prohibited List in effect from January 1, 2026, so athletes who are tested cannot use it. If a clinic has prescribed TB-500 to you, ask it directly what the product is and under what authority it was dispensed, and treat the answer as part of judging the clinic.

Research doses, for information only

Because there is no approved product, there is no label dose to quote. The published human data on injected thymosin beta-4 is a small phase 1 study in healthy volunteers that tested single and repeated intravenous doses from 42 mg up to 1,260 mg and reported them as tolerated over a short period; it did not study the subcutaneous doses in the low milligrams that clinics write, and it measured safety, not recovery. That is the whole of the controlled human evidence for injected use. Nothing on this page is a dose for you; the only dose the calculator takes is the one your clinician prescribed.

TB-500 prescriptions are almost always written in milligrams, while this calculator, like the general peptide tool, takes micrograms so that it works for every peptide. Multiply milligrams by 1,000: 2 mg is 2,000 mcg, 2.5 mg is 2,500 mcg, 0.5 mg is 500 mcg. Entering 2 in the micrograms field for a 2 mg prescription produces a thousandfold underdose, which the result bands are designed to catch.

Reconstitution, storage and why the water volume matters

TB-500 ships as a lyophilized powder, usually in 2, 5 or 10 mg vials. The prescriber or pharmacy specifies the diluent and its volume. Add bacteriostatic water slowly down the glass, swirl rather than shake, and wait until the powder is fully dissolved and the solution is clear before drawing anything. Keep the mixed vial refrigerated, protected from light, and discard it at the beyond-use date given to you even if solution remains.

Because TB-500 doses are large relative to the vial, the water volume decides whether a dose fits one syringe. A 2 mg dose from a 5 mg vial mixed with 1 mL is 0.4 mL, or 40 units; the same dose with 2 mL of water is 80 units and with 3 mL it is 120 units, which no longer fits a 1 mL insulin syringe. Run the calculation again every time the vial strength or water volume changes, and never adjust the water on your own to make the numbers come out: that decision belongs to the pharmacy and clinician who set the concentration.

Methodology and sources

The calculation is standard dimensional analysis for a reconstituted vial, as taught in nursing dosage texts such as Boyer's Math for Nurses, plus the conversion for a U-100 insulin syringe in which 100 units occupy 1 mL. Nothing in it is specific to TB-500; it applies to any lyophilized vial and assumes the full labeled amount dissolved in the water you added. There are three inputs, vial milligrams, water milliliters and prescribed micrograms, and no hidden assumptions about what the dose should be.

How this is calculated, in numbers: a 5 mg vial with 2 mL of bacteriostatic water holds 5 x 1,000 / 2 = 2,500 mcg/mL. A 250 mcg dose is 250 / 2,500 = 0.1 mL, which is 10 units on a U-100 syringe, and the vial holds 20 such doses. For a prescription typical of how TB-500 is written, say 2 mg from the same vial, the dose is 2,000 mcg, so 2,000 / 2,500 = 0.8 mL, or 80 units, and the vial holds 5,000 / 2,000 = 2 full doses with 1 mg left over.

The result bands describe how readable the draw is on an insulin syringe, not whether a dose is right. Below about 5 units a single mark of error is a large share of the dose; between 5 and 50 units the markings are fine enough; between 50 and 100 units the dose fits but fills most of the syringe; above 100 units it does not fit one syringe at all. Each of those is a reason to recheck the inputs or to ask the pharmacy about the diluent volume, never a reason to change the dose.

Medical review: Medical review pending. Last updated .

References

  1. Boyer MJ. Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation. 9th ed. Philadelphia: Wolters Kluwer; 2016. ISBN 978-1-4963-0369-2.
  2. Goldstein AL, Hannappel E, Kleinman HK. Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(10):421-429. doi:10.1016/j.molmed.2005.08.004.
  3. Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. doi:10.1038/nature03000.
  4. Ruff D, Crockford D, Girardi G, Zhang Y. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. doi:10.1111/j.1749-6632.2010.05474.x.
  5. US Food and Drug Administration. Bulk drug substances nominated for use in compounding under section 503A of the Federal Food, Drug, and Cosmetic Act (category list updated May 14, 2026, and the April 22, 2026 version recording the withdrawn nomination) and Certain bulk drug substances for use in compounding that may present significant safety risks (content current as of April 22, 2026), with the FDA briefing document for the Pharmacy Compounding Advisory Committee meeting of July 23 and 24, 2026. Checked October 8, 2026. https://www.fda.gov/media/94155/download, https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks and https://www.fda.gov/media/193342/download

TB-500 Dosage Calculator: Units Per Dose FAQ

No. It converts a dose that a clinician already prescribed into the milliliters and syringe units that deliver it from your particular vial and water volume. There is no dose chart here and no suggested amount, because there is no approved dose to point to and the page is not a prescriber.

Multiply by 1,000 and enter micrograms. A 2 mg dose is 2,000 mcg; 2.5 mg is 2,500 mcg. If you enter 2 for a 2 mg prescription, the calculator will show a draw of a fraction of a unit and flag it as too small to measure, which is your cue to check the conversion.

It is not approved for any indication, and it is not a substance a US pharmacy may compound from bulk. In September 2023 the FDA placed thymosin beta-4 fragment in 503A category 2 for significant safety risks. The nomination was later withdrawn by the nominator: the 503A category list updated April 22, 2026 removed it from category 2 on that ground, and the agency's safety-risk page, current as of April 22, 2026, lists it among the withdrawn nominations. We checked both on October 8, 2026. A withdrawn nomination is a decision by whoever nominated the substance, not an FDA finding that the substance is safe. Section 503A lets a pharmacy compound from a bulk substance only if that substance has a USP or NF monograph, is a component of an FDA-approved drug product, or appears on the 503A bulks list, and TB-500 is none of those. The FDA consulted its advisory committee on July 23, 2026 about adding it, having proposed in its own briefing document that it not be included; that advice is non-binding and the agency had not acted on it as of October 8, 2026. It is also prohibited for tested athletes under section S2.3 of the World Anti-Doping Agency Prohibited List. Ask any clinic prescribing it under what authority it was dispensed.

Thymosin beta-4 is the natural 43-amino-acid protein. TB-500 is a commercial name for synthetic versions, most often the seven-amino-acid fragment (LKKTETQ) that carries the actin-binding activity, and sometimes the full-length peptide. The arithmetic on this page is the same for either; the vial label tells you the milligrams.

The label units were calculated for a specific vial strength and water volume. If this page shows a different number, one of your inputs does not match what the pharmacy assumed. Resolve that with the pharmacy before injecting; do not average the two.

Yes. Your answers and the numbers you enter are scored in your browser and are never sent to us. They stay in this browser tab so you can return to your result, and closing the tab clears them. The only thing the page sends us is a counts-only event: which test was started or completed, the result band and the headline number, with no answers, no entered values and no account. There is nothing to sign up for.

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Important: This calculator is arithmetic on a dose a clinician prescribed for you. It is not a dose suggestion, not an endorsement of TB-500, which is not FDA approved and was not on the 503A bulks list when we checked on October 8, 2026, and not a treatment recommendation. Confirm the vial strength, the diluent volume and the draw with the prescriber or pharmacy before injecting anything. If your symptoms are severe or sudden, seek urgent medical care.