TB-500 reconstitution calculator
Type in a vial size, the diluent volume you added, and a dose figure — the calculator below converts those three numbers into a concentration, a draw volume, and a syringe reading. It performs the same arithmetic as our tirzepatide and sermorelin calculators. What it cannot do, for TB-500 specifically, is check that arithmetic against an FDA-approved product's own label, because no such label — or product — exists. Read why below before you use it.
There is no approved product or dosing standard behind this calculator
TB-500 has never had an FDA-approved drug product of its own — a direct check against DailyMed, the National Library of Medicine's official archive of FDA-approved drug labeling, returns zero results for both "TB-500" and "thymosin." TB-500 is also not the same molecule as the naturally occurring protein it is named after: it is a synthetic 7-amino-acid fragment of the 43-amino-acid protein thymosin beta-4, and most of the research cited in TB-500 marketing was conducted on the full-length protein, not the fragment sold as TB-500 — a distinction worth knowing before you weigh any claims about it.
Its compounding status is also unsettled, and has moved recently: TB-500 sat on FDA's interim Section 503A Category 2 list (bulk substances presenting significant safety risks that pharmacies should not compound) from 2023 until April 15, 2026, when FDA removed it — along with eleven other peptides — because the nomination behind that listing was withdrawn. That removal does not make compounding TB-500 legal; it only lifts the "significant safety risk" flag and leaves it outside every category while further review continues. That review is already underway: at FDA's Pharmacy Compounding Advisory Committee meeting on July 23-24, 2026, the committee voted 8-6-1 to recommend adding TB-500 to the 503A bulks list, over dissenting members' objections that FDA staff reviewers could not identify a single human clinical study of TB-500 itself. A committee recommendation is not final agency action — as of this page's last review, FDA had not yet formally added TB-500 to the list.
What the tool below actually does is narrower than that context might suggest: it takes the vial size, diluent volume, and dose you type in and returns the concentration and draw volume that arithmetic implies — nothing more. It cannot confirm that a particular vial is what its label claims, that the dose you enter is appropriate for you, that it is currently legal for a pharmacy to have compounded it, or that the product you drew that number from came from a legitimate source. A correct-looking syringe reading is not evidence that any of those things are true.
Sources: DailyMed structured-product-label search for "TB-500" and "thymosin" (zero results for both), FDA's April 15, 2026 removal of TB-500 from the interim Section 503A Category 2 bulk drug substances list, and FDA's July 23-24, 2026 Pharmacy Compounding Advisory Committee vote on TB-500, all independently checked 2026-08-02. View the DailyMed search.
Where to go next
- Compare against the compounds this calculator supports that do have an FDA-approved reference product, on the calculator hub.
Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.