Follistatin is not a small peptide. Its compound page calls it an activin-binding glycoprotein, “with substantially larger molecular weight and structural complexity.” The arithmetic below still converts milligrams correctly, because mass is mass, but a milligram figure says nothing about how many follistatin molecules that is, which variant they are, or whether they are active. The explainer under the calculator sets out why. No follistatin dose appears on this page; the compound is covered in the follistatin guide.
A 1 mg vial of Follistatin reconstituted with 1 mL of bacteriostatic water gives a concentration of 1.0 mg/mL, or 10 mcg per unit on a U-100 syringe.
Defaults: 1 mg is the labelled vial on all 7 follistatin tests on file, 21 Sep 2026; 1 mL was chosen for simple arithmetic and is not a sourced volume. Peptigrity publishes no Follistatin dose, so the dose field starts empty.
Draw the syringe up to
Enter your own amount to see the draw. Add 1 mL of water to your 1 mg vial first.
Follistatin has 7 independent lab tests on file at Peptigrity, averaging 99.02% HPLC purity across the tests that report one. Purity is not net content: a clean certificate confirms what is in a vial, not how much. See the Follistatin lab-test records.
Every number on this page is mass arithmetic. Dissolve a 1 mg vial in 1 mL of water and the solution holds 1 mg/mL; each unit on a U-100 syringe then carries 10 mcg of whatever the vial contained. That holds for any solid that dissolves, protein or peptide, so the conversion is not wrong for follistatin. What changes with a protein this large is what the milligram can be taken to mean.
Molar amount. Turning milligrams into a number of molecules needs a molecular weight. For a short peptide the site states one (Pinealon's free tripeptide is 418.4 Da); for follistatin it states none, only that the molecule is far larger and more complex than a small peptide. For scale, the follistatin page's own comparison lists BPC-157 as a 15-amino-acid peptide, and the follistatin-344 page describes FS-344 as a 344-amino-acid precursor. Several variants (FS-288, FS-315, FS-344) are sold under the one name, so the same milligram figure need not describe the same molecule from vial to vial. This page does not convert to moles, and a molar figure quoted without a stated variant and molecular weight cannot be checked.
Activity. A mass says how much material is present, not what it does. The compound page notes that follistatin is typically made by recombinant expression, that its quality control is “fundamentally different and more variable” than a small peptide's, and that its glycoprotein nature “limits the discriminating power of standard peptide tests”, so HPLC, mass spectrometry and ideally glycosylation analysis matter more. Peptigrity's own certificate checklist adds that a perfect certificate confirms the molecule and the quantity and “says nothing about efficacy”.
The label. The milligram the calculator starts from is the label's, not the vial's. The seven follistatin records on the lab-test listing (21 Sep 2026) are all labelled 1 mg; their measured net content ran from 0.6 mg to 1.32 mg. At a nominal 1 mg/mL, the 10 units this page gives for 100 mcg would have carried anywhere from 60 to 132 mcg of material from those vials. Their sample identities do not agree on a variant either: four name follistatin-344, two name no variant, and one reads “Follistatin-334”.
The table sorts the questions a follistatin vial raises by whether mass arithmetic can answer them, from the follistatin and follistatin-344 compound pages (Last Updated: August 2026) and the lab-test listing (21 Sep 2026).
| Question | Can this calculator answer it? | Why |
|---|---|---|
| Milligrams per mL after reconstitution | Yes | Labelled vial mass ÷ water volume |
| Micrograms per syringe unit | Yes | mg/mL × 10 on a U-100 syringe |
| Number of molecules (molar amount) | No | No molecular weight is stated for follistatin, and the variants sold under the name differ in length |
| Which variant is in the vial | No | Only identity testing on a certificate; the compound page says to verify which variant is being sold |
| Whether the protein is active | No | Neither mass nor HPLC purity measures activity |
| Whether the vial holds its labelled 1 mg | No | Measured net content on file ran from 0.6 mg to 1.32 mg against 1 mg labels |
The table sets out what the follistatin compound page states (Last Updated: August 2026).
| Question | What the compound page states | Evidence level |
|---|---|---|
| What is it? | An activin-binding glycoprotein that neutralizes myostatin (GDF-8); “a glycoprotein rather than a small peptide” | Established biology (myostatin pathway) |
| Which form? | Several variants (FS-288, FS-315, FS-344) with different tissue-binding properties | Chemical identity |
| Human studies? | Phase 1/2 research in Duchenne muscular dystrophy and inclusion body myositis contexts with limited efficacy signals; AAV-follistatin gene therapy at an earlier stage | Phase 1/2; no Phase 3 approval |
| A route? | Not stated. The side-effects paragraph mentions injection-site reactions among reports; that is safety text, not a route statement | None stated |
| An approved dose? | Not approved for any medical indication anywhere in the world (as of August 2026) | None |
| A research dose? | None stated; “research-use dosing varies widely”, and Peptigrity does not recommend a dose | None — declined |
The compound page also flags that the mechanism raises theoretical concerns about cardiac muscle, where myostatin is also expressed, and about reproductive function through activin, and that long-term safety at sustained use is not characterized at Western RCT standards.
The table converts reference quantities to syringe units at the default of 1.0 mg/mL (1 mg of Follistatin in 1 mL), and counts how many draws of each a vial holds. Every row is arithmetic, not a dose: read the units for the amount you already intend to measure.
| Quantity | Draw at 1.0 mg/mL | Volume | Draws from a 1 mg vial |
|---|---|---|---|
| 25 mcg | 2.5 units | 0.025 mL | 40 |
| 50 mcg | 5.0 units | 0.05 mL | 20 |
| 100 mcg | 10.0 units | 0.10 mL | 10 |
| 250 mcg | 25.0 units | 0.25 mL | 4 |
| 500 mcg | 50.0 units | 0.50 mL | 2 |
The same Follistatin quantity lands on a different mark depending on how much water went into the vial. Read down the column for the concentration you actually mixed; a units figure carried across from another column is simply wrong.
| Quantity | At 2.0 mg/mL (1 mg + 0.5 mL) | At 1.0 mg/mL (1 mg + 1 mL) | At 0.50 mg/mL (1 mg + 2 mL) |
|---|---|---|---|
| 25 mcg | 1.3 units | 2.5 units | 5.0 units |
| 50 mcg | 2.5 units | 5.0 units | 10.0 units |
| 100 mcg | 5.0 units | 10.0 units | 20.0 units |
| 250 mcg | 12.5 units | 25.0 units | 50.0 units |
| 500 mcg | 25.0 units | 50.0 units | 100.0 units |
Every cell is the same arithmetic: units = (quantity in mg ÷ concentration in mg/mL) × 100 on a U-100 syringe. More water spreads the same mass over more units, which is the fix when a small quantity would otherwise sit at two or three units, where a one-unit misread is a large error.
Each Follistatin vial holds as many draws as its labelled mass divided by the quantity per draw; the water volume changes nothing about it. The grid counts draws, not weeks — this page states no frequency.
| Vial size | At 25 mcg | At 50 mcg | At 100 mcg | At 250 mcg | At 500 mcg |
|---|---|---|---|---|---|
| 1 mg | 40 | 20 | 10 | 4 | 2 |
The labelled mass is not a guarantee of the mass in your vial: net content is a separate measurement from purity, and certificates on file often measure a few percent above or below the label.
No label sets a diluent volume for research-grade follistatin, and the compound page states none, so the volume is a choice; the 1 mL default here was picked because it makes the arithmetic plain (1 mg/mL, 10 mcg per unit). The site's handling guides, reconstituting peptides step by step and the bacteriostatic water guide, are written for peptides; nothing in them is a follistatin-specific finding. For testing, the compound page points to the how-to-test hub with its own caveat that peptide-specific guidance does not all directly apply to glycoproteins.
The two compound pages describe the same protein at different levels of specificity: follistatin-344 is a particular isoform of follistatin, not a separate molecule, and the follistatin page says their data should be read together, not merged. FS-344 is the 344-amino-acid precursor, processed in the body toward the circulating FS-315 form. See the follistatin-344 page and its lab-test records.
Follistatin is not approved for any medical indication anywhere in the world as of August 2026. Phase 1/2 clinical research in muscular dystrophy contexts did not advance to Phase 3 approval, and the compound was not specifically included in the April 2026 FDA Category 2 removals. It is sold strictly as a research-use-only material by third-party laboratories. For tested athletes, the compound page states that follistatin is named on the WADA Prohibited List under S4.3 (Agents Preventing Activin Receptor IIB Activation), which prohibits “myostatin-binding proteins (e.g. follistatin)” at all times, in and out of competition. Background: do peptides show up on drug tests.
Independent test records: follistatin lab tests. Tracked listings: follistatin price per milligram.
Not by its compound page's description. Follistatin is an activin-binding glycoprotein, which the page calls a glycoprotein rather than a small peptide, with substantially larger molecular weight and structural complexity. It is sold by mass in 1 mg vials, which is why mass arithmetic still applies to it.
At the page default of 1 mg/mL (a 1 mg vial with 1 mL of water), each unit on a U-100 syringe carries 10 mcg, so 100 mcg is 10 units (0.1 mL). With 2 mL in the same vial (0.5 mg/mL) it is 20 units. That is mass only: it says nothing about molar amount or activity, and measured net content on file has ranged from 0.6 mg to 1.32 mg per labelled 1 mg vial.
There isn't one. Follistatin is not approved for any medical indication anywhere in the world, its human research is Phase 1/2 work in muscular dystrophy contexts that did not advance to Phase 3, and Peptigrity does not recommend a dose; the compound page notes that research-use dosing varies widely. This page converts a mass you already have in mind; it does not supply one.
Not from anything Peptigrity publishes. A molar conversion needs a molecular weight, and the site states none for follistatin; the variants sold under the name (FS-288, FS-315, FS-344) differ in length. Activity is not a mass property at all: neither this calculator nor an HPLC purity figure measures it.
Follistatin-344 is a particular isoform of follistatin, not a separate molecule: the 344-amino-acid precursor that the body processes toward the circulating FS-315 form. Peptigrity keeps a page for each and says their data should be read together, not merged.
Yes. The follistatin compound page states that it is named on the WADA Prohibited List under S4.3 (Agents Preventing Activin Receptor IIB Activation), the subsection that prohibits myostatin-binding proteins such as follistatin, at all times, in and out of competition.