Reconstituting a Semax vial comes down to one number: how many units do you draw on the syringe? This calculator gives you that in one step. Enter how many milligrams are in your vial, how much bacteriostatic water you're adding, and your target microgram dose, and it returns the exact insulin-syringe mark, the concentration you've made, and how many doses the vial holds.
Semax, a synthetic ACTH(4-10) analog, is dosed in micrograms — community subcutaneous routines commonly use 200 to 600 mcg — out of a 5 mg or 10 mg vial that holds thousands of micrograms. If you want the general tool that spans every compound rather than this Semax-specific one, the all-purpose peptide dosage calculator runs the same math. That makes an injected Semax draw small, often around 12 units, where reading the mark accurately matters more than anything. Two honest notes up front: Semax is most often used intranasally (the clinically studied route), and there's a longer-lasting N-Acetyl Semax variant — this calculator's unit math is for the injectable form, and we point you to the right place for the rest. Below the tool we walk through the math, the routes, and what real Semax users mix.
Key Takeaways
- Two-step math (in mcg): concentration = vial mcg ÷ bac water mL, then units = (dose mcg ÷ concentration) × 100 on a U-100 syringe.
- Anchor example: a 5 mg vial + 2 mL of bacteriostatic water = 2,500 mcg/mL; a 300 mcg dose = 0.12 mL = 12 units, and the vial yields 16 doses.
- Injected Semax draws are small. Our usage data shows a median draw of about 8 units, so reading the mark precisely matters; a U-50 syringe helps.
- Routes differ: Semax is widely used as nasal drops, and N-Acetyl Semax is a separate variant. This calculator is for subcutaneous injection of plain Semax.
- One vial is many doses. At ~300 mcg, a 5 mg vial holds about 16 doses, so cost per dose is low.
- Not FDA-approved. Semax is a registered medicine in Russia and Ukraine, not approved in the US. Treat every figure as calculation context, not advice.
| You enter | Value | The calculator returns | Value |
|---|---|---|---|
| Semax in vial | 5 mg | Concentration | 2,500 mcg/mL |
| Bacteriostatic water | 2 mL | Volume to draw | 0.12 mL |
| Target dose | 300 mcg | Draw to this mark | 12 units (U-100) |
| Syringe type | U-100 | Doses per vial | 16 |
How do you calculate a Semax dose?
Semax reconstitution is two steps, both in micrograms: work out the vial's concentration, then convert your microgram dose into a volume you can read on the syringe. The units you draw are simply that volume on the insulin scale.
In plain arithmetic, keeping everything in micrograms:
- Concentration (mcg/mL) = vial mcg ÷ bac water mL. A 5 mg vial is 5,000 mcg; in 2 mL that's 5,000 ÷ 2 = 2,500 mcg/mL.
- Volume (mL) = dose mcg ÷ concentration. A 300 mcg dose at 2,500 mcg/mL is 300 ÷ 2,500 = 0.12 mL.
- Units = volume × 100 on a U-100 syringe (100 units = 1 mL). So 0.12 mL = 12 units.
Collapsed into the single formula the calculator runs:
units = (dose mcg ÷ (vial mcg ÷ bac water mL)) × 100 = dose mcg × bac water mL ÷ vial mcg × 100
Sanity-check our example: 300 × 2 ÷ 5,000 × 100 = 12 units. For doses per vial, divide the vial's micrograms by your dose: 5,000 mcg ÷ 300 mcg ≈ 16 doses.
Our take: The arithmetic is the same for any microgram peptide; what's specific to Semax is the decision around it. Most clinical Semax use is intranasal, and an injected protocol is a community extension without an official label — so be clear that the unit math here is for the injectable route, then focus on reading a small 8-to-15-unit draw cleanly. Concentration and syringe choice are the two levers that make that precise.
Semax routes: nasal drops, injection, and N-Acetyl Semax
Semax is used as intranasal drops, as a subcutaneous injection, and as the longer-acting N-Acetyl Semax variant — and this calculator's unit math applies only to injecting plain Semax, because nasal dosing is counted in drops, not syringe units. Pick the right method for your form.
Three distinctions matter:
- Nasal vs injection. The clinically studied form of Semax in Russia and Ukraine is an intranasal solution, used for stroke recovery and cognition. If you use nasal drops, the vial-to-units conversion here doesn't apply — see our Semax nasal-spray dosing guide.
- N-Acetyl Semax (and the amidate). N-Acetyl Semax is an acetylated, longer-lasting variant; its doses and behavior differ, so don't carry plain-Semax numbers across to it. See our N-Acetyl Semax guide.
- Semax vs Selank. People often compare the two. Semax is the ACTH-derived, cognition-and-recovery peptide; Selank is the tuftsin-derived, anxiolytic one. Their dosing math is identical, but they aren't interchangeable.
Everything below assumes you're reconstituting plain Semax to inject subcutaneously.
Why are injected Semax draws so small, and what do real users mix?
Because a Semax dose (a few hundred micrograms) is a tiny fraction of the thousands of micrograms in the vial, the injected volume is small — usually well under 15 units — so every reconstitution choice is about making that small draw readable. Concentration is the lever.
A 5 mg vial holds 5,000 mcg, so even a 600 mcg dose is just over a tenth of it. The draw shrinks with the dose and grows with the water. Because ProtocolPlus tracks reconstitutions, we can show the vial-strength × water-volume combinations real Semax users log for injection.
The pattern: 2 mL is the dominant water choice across both vial sizes. A 5 mg vial in 2 mL gives 2,500 mcg/mL, where a 300 mcg dose is a readable 12 units; a 10 mg vial in 2 mL gives 5,000 mcg/mL, where the same dose is a tighter 6 units. People favor 2 mL because 1 mL would shrink an already-small draw toward the unreadable end of the scale.
A worked walkthrough: choosing water for a readable draw
Say you have a 5 mg vial and your dose is 300 mcg. Run the candidate water volumes:
- 1 mL → 5,000 mcg/mL. 300 mcg = 6 units. Small and easy to misread by a unit.
- 2 mL → 2,500 mcg/mL. 300 mcg = 12 units. Comfortable on a U-100 barrel.
- 3 mL → 1,667 mcg/mL. 300 mcg = 18 units. The easiest read, if the vial holds the volume.
For Semax the winner is usually the higher practical water volume. If a small dose lands under about 3 units on a strong vial, switch to a U-50 or U-30 syringe, whose marks are spaced further apart.
How do you convert Semax mcg to insulin units, and read a tiny draw?
Divide your microgram dose by the vial's mcg-per-mL concentration to get millilitres, then multiply by 100 for U-100 units — the shortcut is that at 2,500 mcg/mL, every 25 mcg is one unit. Units measure liquid volume, not micrograms of Semax.
Across our tracked Semax injections the median draw is just 8 units, with most under 15. At that scale, syringe choice is the biggest precision lever you have.
The distribution hugs the low end of the barrel. Three calibrations exist (U-100, U-50, U-40); for Semax, a U-50 or U-30 barrel is often the better tool, because it stretches a small draw across more readable spacing. Always confirm which syringe you're holding, since a unit means a different volume on each.
Semax reconstitution chart: units by vial and dose
This chart shows the concentration each vial makes at the common water volumes and the U-100 units to draw, so you can pick a setup that lands your injected dose on a readable mark. For any other setup, use the calculator.
| Setup | Concentration | 200 mcg | 300 mcg | 600 mcg |
|---|---|---|---|---|
| 5 mg + 1 mL | 5,000 mcg/mL | 4 u | 6 u | 12 u |
| 5 mg + 2 mL | 2,500 mcg/mL | 8 u | 12 u | 24 u |
| 10 mg + 2 mL | 5,000 mcg/mL | 4 u | 6 u | 12 u |
| 10 mg + 3 mL | 3,333 mcg/mL | 6 u | 9 u | 18 u |
The most readable setups for a typical 200–300 mcg dose are the more dilute ones (5 mg + 2 mL, or 10 mg + 3 mL), which lift the draw into the 8-to-12-unit range. The most-searched single conversions, for a quick sanity check:
- 200 mcg Semax on a 2,500 mcg/mL vial = 0.08 mL = 8 units; on a 5,000 mcg/mL vial = 4 units.
- 300 mcg Semax on a 2,500 mcg/mL vial = 0.12 mL = 12 units.
- 600 mcg Semax on a 2,500 mcg/mL vial = 0.24 mL = 24 units.
How many Semax doses are in a vial, and what does each cost?
Doses per vial is vial micrograms ÷ your dose — and because Semax doses are small, a single vial holds many. Dividing the vial price by that number gives a true cost per dose.
A 5 mg (5,000 mcg) vial at a 300 mcg dose yields about 16 doses; at 200 mcg it's 25. Across our tracked Semax vials the median works out to roughly 25 doses per completed vial at about $1.90 per dose.
| Economics output | How it's computed | Example (5 mg vial, 300 mcg dose, $47 vial) |
|---|---|---|
| Doses per vial | vial mcg ÷ dose mcg | 16 doses |
| Cost per dose | vial price ÷ doses per vial | $2.94 |
| Weekly cost | cost per dose × doses per week | $14.70 (5×/week) |
| Approx. monthly cost | weekly × 4.3 | ~$63 |
For a full course rather than a single calculation, see our Semax dosing and protocol guide.
mcg, mg, units, and mL: keeping the four numbers straight
Micrograms measure the Semax; millilitres and units measure the liquid you draw. The dangerous slip is reading a microgram dose as if it were milligrams — a 1,000× error. Keep the families separate and the math is easy.
Semax is dosed in micrograms (200–600 mcg), like Selank or sermorelin, so if you switch from a milligram peptide, watch the unit. 1 mg = 1,000 mcg. Here is a 300 mcg dose expressed four ways on a 2,500 mcg/mL vial:
| Label | Value | What it describes |
|---|---|---|
| Dose in micrograms | 300 mcg | mass of Semax |
| Dose in milligrams | 0.3 mg | mass of Semax |
| Volume to draw | 0.12 mL | liquid volume |
| Units to draw (U-100) | 12 units | liquid volume on the syringe |
Why concentration is the number that actually matters
Concentration (mcg/mL) is the hinge of every Semax calculation — and for Semax it's what decides whether your tiny injected dose lands on a readable mark. It connects the micrograms in the vial to the units on the syringe.
Concentration is an exchange rate between micrograms of Semax and millilitres of liquid. A 2,500 mcg/mL vial trades every 1 mL for 2,500 mcg; your dose occupies a volume set by that rate, and the syringe scale turns it into a unit mark. Make the vial weaker (more water) and the same dose occupies more volume — more units, and an easier read.
It's also why you can never compare unit numbers across reconstitutions. "Draw 12 units" means 300 mcg on a 2,500 mcg/mL vial but 600 mcg on a 5,000 mcg/mL vial — double. Every unit instruction online is valid only for that exact vial and water volume.
How to reconstitute Semax, step by step
Add the bacteriostatic water slowly down the vial wall, swirl gently until clear, and never shake. The peptide is delicate, and rough mixing degrades it before your first dose.
- Calculate first. Use the tool above to set your water volume and target unit mark, and check the precision flag.
- Room temperature, then swab both stoppers with a fresh alcohol swab.
- Draw your measured water into a reconstitution syringe.
- Add slowly down the wall of the Semax vial, onto the glass rather than the powder.
- Swirl, don't shake until the solution is completely clear.
- Inspect. Clear and particle-free, or don't use it.
- Label and refrigerate at 2–8 °C, away from light, then dose at the unit mark the calculator gave you.
Common Semax reconstitution mistakes
- Using too little water. With Semax, that shrinks the injected draw toward the unreadable end — usually you want more.
- Confusing mcg with mg. A 1,000× error; Semax is micrograms.
- Carrying nasal or N-Acetyl numbers across. Different route, different variant, different dosing — use the right method.
- Copying someone else's unit count. Valid only for that person's exact concentration.
- Freeze-thaw and light exposure, and not labeling the date.
Semax vial sizes, supplies, and water
Semax usually comes in 5 mg or 10 mg vials (30 mg exists), and either works fine for injection — the vial size mostly changes how many doses you get and the concentration you mix to. Pick the water volume that lands your dose on a readable mark.
- 5 mg — common; in 2 mL it's 2,500 mcg/mL, where a 300 mcg dose is a clean 12 units and the vial gives about 16 doses.
- 10 mg — in 2 mL it's 5,000 mcg/mL (tighter draws), or in 3–4 mL it dilutes back to readable marks with about 33 doses per vial.
A quick supplies checklist: the lyophilized Semax vial, bacteriostatic water (sterile water with 0.9% benzyl alcohol) as the diluent, a reconstitution syringe (1–3 mL), a U-100 or U-50 insulin syringe (a U-50 reads small draws better), alcohol swabs, and a marker for the date.
How long does reconstituted Semax last?
Once mixed, Semax is far less stable than the dry powder, and there's no validated shelf life — the common ~28-day refrigerated convention is a usage habit, not data. Judge by appearance, not just the calendar.
Peptides in solution degrade through hydrolysis, deamidation, oxidation, and aggregation, sped up by heat, light, and agitation, so a mixed vial belongs in the refrigerator at 2–8 °C, kept dark, and never frozen — Semax in particular is worth protecting from light and freeze-thaw. In our usage data the median reconstituted Semax vial is finished in about 23 days. Discard any vial that turns cloudy, changes color, or shows particles. For the deeper science, see our peptide storage and stability guide.
What the evidence says about Semax dosing
Semax's dosing figures come from Russian and Ukrainian clinical use and community practice, not FDA-reviewed trials — and most of that clinical use is intranasal — so the injected microgram amounts are conventions, not validated human doses. We give them only so you know what to enter into the calculator.
Semax is a synthetic analog of an ACTH(4-10) fragment, the heptapeptide Met-Glu-His-Phe-Pro-Gly-Pro, developed in Russia and used there as a medicine for stroke and cognition, and one of the best peptides for focus and cognition in community use. Mechanistic work links it to upregulation of brain-derived neurotrophic factor and its receptor (Brain Research, 2006, Dolotov et al., "Semax regulates BDNF and trkB expression", retrieved 2026-06-16), and to neurotrophin transcription and neuroprotection in models of cerebral ischemia (NCBI/PMC, 2024, "Semax and Pro-Gly-Pro activate neurotrophins after ischemia", retrieved 2026-06-16; NCBI/PMC, 2021, "Protective effect of ACTH(4-7)PGP in ischemia-reperfusion", retrieved 2026-06-16). Early human work documented effects on the electroencephalogram (PubMed, 1996, "Effect of heptapeptide Semax on human EEG", retrieved 2026-06-16). There is no FDA-approved label or standard US dose, and no official injectable protocol. Treat the common 200–600 mcg figures as a community convention to calculate from if you choose to, not as evidence-based guidance.
How precise does your Semax draw need to be?
Because injected Semax draws are small (often 6–15 units), precision matters: at 2,500 mcg/mL, one U-100 unit is 25 mcg, so being off by a single unit on a 12-unit draw shifts a 300 mcg dose by about 8 percent. That's the argument for using enough water to spread the draw and, for the smallest doses, a U-50 or U-30 syringe.
Frequently asked questions
Sources
Factual claims (origin, regulatory status, evidence) are sourced below. Dose values in examples are for calculation only, not recommendations; the 200–600 mcg figures are community convention, not a validated label. ProtocolPlus usage figures are first-party app data.
- Brain Research (2006) — Dolotov OV, et al., Semax, an analog of ACTH(4-10), regulates BDNF and trkB expression in the rat hippocampus. https://www.sciencedirect.com/science/article/abs/pii/S0006899306022955 — retrieved 2026-06-16.
- NCBI / PMC11498467 (2024) — Semax and Pro-Gly-Pro activate transcription of neurotrophins after cerebral ischemia. https://pmc.ncbi.nlm.nih.gov/articles/PMC11498467/ — retrieved 2026-06-16.
- NCBI / PMC8226508 (2021) — Protective effect of ACTH(4-7)PGP (Semax) in rat cerebral ischemia-reperfusion. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8226508/ — retrieved 2026-06-16.
- PubMed (1996) — Effect of the heptapeptide Semax on the human electroencephalogram. https://pubmed.ncbi.nlm.nih.gov/8679991/ — retrieved 2026-06-16.
About this guide. Written by Jordan Vance, peptide and biohacking researcher (placeholder, replace before publish), and medically reviewed by Dr. Maya Ellison, MD, biochemistry (placeholder, replace before publish), for the ProtocolPlus Research Team. This calculator and article are educational and not medical advice.