Reconstituting a Selank 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.
Selank, a synthetic tuftsin analog, is dosed in micrograms — community subcutaneous routines commonly use 250 to 500 mcg — out of a 5 mg or 10 mg vial that holds thousands of micrograms. If you want the general tool across compounds rather than this Selank-specific one, the all-purpose peptide dosage calculator covers the same math. That makes an injected Selank draw tiny, often around 10 units, and the real challenge is reading such a small mark accurately. One honest note up front: many people use Selank intranasally rather than by injection, and this tool is for the injectable route; we cover the nasal option briefly below and link out. Below the tool we walk through the math, the nasal-versus-injection choice, and what real Selank 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 250 mcg dose = 0.1 mL = 10 units, and the vial yields 20 doses.
- Injected Selank 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.
- Nasal vs injection: Selank is widely used as nasal drops; this calculator is for subcutaneous injection. If you use it nasally, the unit math here doesn't apply — see the note below.
- One vial is many doses. At ~250 mcg, a 5 mg vial holds about 20 doses, so cost per dose is low.
- Not FDA-approved. Selank is a registered medicine in Russia, not approved in the US. Treat every figure as calculation context, not advice.
| You enter | Value | The calculator returns | Value |
|---|---|---|---|
| Selank in vial | 5 mg | Concentration | 2,500 mcg/mL |
| Bacteriostatic water | 2 mL | Volume to draw | 0.1 mL |
| Target dose | 250 mcg | Draw to this mark | 10 units (U-100) |
| Syringe type | U-100 | Doses per vial | 20 |
How do you calculate a Selank dose?
Selank 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 250 mcg dose at 2,500 mcg/mL is 250 ÷ 2,500 = 0.1 mL.
- Units = volume × 100 on a U-100 syringe (100 units = 1 mL). So 0.1 mL = 10 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: 250 × 2 ÷ 5,000 × 100 = 10 units. For doses per vial, divide the vial's micrograms by your dose: 5,000 mcg ÷ 250 mcg = 20 doses.
Our take: With Selank the arithmetic is easy; the subtlety is the size of the draw. A 250 mcg dose is one-twentieth of a 5 mg vial, so you're reading a 10-unit mark where a single unit of error is 10 percent of the dose. The levers that matter are concentration (enough water to spread the draw onto readable marks) and syringe choice (a U-50 doubles the mark spacing). And before any of that: decide whether you're injecting at all, or using Selank nasally.
Selank: nasal drops versus subcutaneous injection
Selank is widely used as intranasal drops as well as by subcutaneous injection — and this calculator's unit math applies only to injection, because nasal dosing is measured in drops or sprays, not syringe units. Pick your route first, then use the right tool.
The clinically studied form of Selank in Russia is an intranasal solution, and many people outside research settings use a nasal spray for convenience. If that's you, the vial-to-units conversion here doesn't apply — nasal dosing is counted in drops or metered sprays of a known concentration, and converting a reconstituted vial into a nasal bottle is a separate calculation. This page is for the people reconstituting a lyophilized vial to inject subcutaneously, where the dose becomes a unit mark on an insulin syringe. For the nasal route and bottle conversions, see our Selank nasal-spray dosing guide. Everything below assumes injection.
Why are injected Selank draws so small, and what do real users mix?
Because a Selank 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. Even a 500 mcg dose is one-tenth of it. The draw shrinks with the dose and grows with the water, which is why the water volume you pick is really a readability decision. Because ProtocolPlus tracks reconstitutions, we can show the vial-strength × water-volume combinations real Selank 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 250 mcg dose is a readable 10 units; a 10 mg vial in 2 mL gives 5,000 mcg/mL, where the same dose is a tighter 5 units. People reach for 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 250 mcg. Run the candidate water volumes:
- 1 mL → 5,000 mcg/mL. 250 mcg = 5 units. Small and easy to misread by a unit.
- 2 mL → 2,500 mcg/mL. 250 mcg = 10 units. Comfortable on a U-100 barrel.
- 3 mL → 1,667 mcg/mL. 250 mcg = 15 units. Even easier to read, if the vial holds the volume.
For Selank the winner is usually the higher practical water volume, the reverse of a milligram-dosed peptide. If a dose still lands under about 3 units, switch to a U-50 syringe, whose marks are twice as far apart.
How do you convert Selank 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 Selank.
Across our tracked Selank injections the median draw is just 8 units, with most under 15. At that scale, syringe choice is the biggest precision lever you have: a U-50 (50 units = 0.5 mL) spreads the same volume across marks twice as far apart as a U-100.
The distribution hugs the low end of the barrel. Three calibrations exist (U-100, U-50, U-40); for Selank, a U-50 0.3 mL barrel is often the better tool, because it stretches a 5-to-15-unit draw across more readable spacing. Always confirm which syringe you're holding, since a unit means a different volume on each.
Selank 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 | 250 mcg | 300 mcg | 500 mcg |
|---|---|---|---|---|
| 5 mg + 1 mL | 5,000 mcg/mL | 5 u | 6 u | 10 u |
| 5 mg + 2 mL | 2,500 mcg/mL | 10 u | 12 u | 20 u |
| 10 mg + 2 mL | 5,000 mcg/mL | 5 u | 6 u | 10 u |
| 10 mg + 3 mL | 3,333 mcg/mL | 7.5 u | 9 u | 15 u |
The most readable setups for a typical 250–300 mcg dose are the more dilute ones (5 mg + 2 mL, or 10 mg + 3 mL), which lift the draw into the 7-to-12-unit range. The most-searched single conversions, for a quick sanity check:
- 250 mcg Selank on a 2,500 mcg/mL vial = 0.1 mL = 10 units; on a 5,000 mcg/mL vial = 5 units.
- 300 mcg Selank on a 2,500 mcg/mL vial = 0.12 mL = 12 units.
- 500 mcg Selank on a 2,500 mcg/mL vial = 0.2 mL = 20 units.
How many Selank doses are in a vial, and what does each cost?
Doses per vial is vial micrograms ÷ your dose — and because Selank 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 250 mcg dose yields 20 doses; at 500 mcg it's 10. Across our tracked Selank vials the median works out to roughly 20 doses per completed vial at about $2.40 per dose.
| Economics output | How it's computed | Example (5 mg vial, 250 mcg dose, $47 vial) |
|---|---|---|
| Doses per vial | vial mcg ÷ dose mcg | 20 doses |
| Cost per dose | vial price ÷ doses per vial | $2.35 |
| Weekly cost | cost per dose × doses per week | $16.45 (7×/week) |
| Approx. monthly cost | weekly × 4.3 | ~$71 |
For a full course rather than a single calculation, see our Selank dosing and protocol guide.
mcg, mg, units, and mL: keeping the four numbers straight
Micrograms measure the Selank; 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.
Selank is dosed in micrograms (250–500 mcg), like Semax or sermorelin, so if you switch from a milligram peptide, watch the unit. 1 mg = 1,000 mcg. Here is a 250 mcg dose expressed four ways on a 2,500 mcg/mL vial:
| Label | Value | What it describes |
|---|---|---|
| Dose in micrograms | 250 mcg | mass of Selank |
| Dose in milligrams | 0.25 mg | mass of Selank |
| Volume to draw | 0.1 mL | liquid volume |
| Units to draw (U-100) | 10 units | liquid volume on the syringe |
Why concentration is the number that actually matters
Concentration (mcg/mL) is the hinge of every Selank calculation — and for Selank 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 Selank 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 10 units" means 250 mcg on a 2,500 mcg/mL vial but 500 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 Selank, 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 Selank 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, then dose at the unit mark the calculator gave you.
Common Selank reconstitution mistakes
- Using too little water. With Selank, that shrinks the injected draw toward the unreadable end — usually you want more.
- Confusing mcg with mg. A 1,000× error; Selank is micrograms.
- Mixing up nasal and injectable dosing. Nasal drops are not measured in syringe units; use the right method for your route.
- Copying someone else's unit count. Valid only for that person's exact concentration.
- Wrong syringe (a U-100 barrel makes a tiny draw harder to read than a U-50), and not labeling the date.
Selank vial sizes, supplies, and water
Selank usually comes in 5 mg or 10 mg vials, 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 250 mcg dose is a clean 10 units and the vial gives about 20 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 40 doses per vial.
A quick supplies checklist: the lyophilized Selank 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 Selank last?
Once mixed, Selank 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. In our usage data the median reconstituted Selank vial is finished in about 24 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 Selank dosing
Selank's dosing figures come from Russian 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.
Selank is a synthetic analog of the immunomodulatory peptide tuftsin, developed at Russia's Institute of Molecular Genetics, where it is a registered medicine studied mainly for anxiety and a frequent name among the best peptides for focus and cognition. Animal and mechanistic work links it to GABAergic and serotonergic signaling and to changes in anxiety-related gene expression (NCBI/PMC, 2016, "Selank and GABAergic gene expression", retrieved 2026-06-16), and it has been shown to enhance the anxiolytic effect of benzodiazepines in stressed animals (NCBI/PMC, 2017, "Selank enhances diazepam anxiolysis", retrieved 2026-06-16). Small Russian human studies report immunomodulatory and anxiolytic effects in anxiety-asthenic patients (PubMed, 2008, "Immunomodulatory effects of selank", retrieved 2026-06-16), within a broader literature on tuftsin-family peptides in psychopharmacology (PubMed, 2004, "Selank and tuftsin peptides", retrieved 2026-06-16). There is no FDA-approved label or standard US dose. Treat the common 250–500 mcg figures as a community convention to calculate from if you choose to, not as evidence-based guidance.
How precise does your Selank draw need to be?
Because injected Selank draws are small (often 5–12 units), precision matters: at 2,500 mcg/mL, one U-100 unit is 25 mcg, so being off by a single unit on a 10-unit draw shifts a 250 mcg dose by 10 percent. That's the argument for using enough water to spread the draw and, for the smallest doses, a U-50 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 250–500 mcg figures are community convention, not a validated label. ProtocolPlus usage figures are first-party app data.
- NCBI / PMC4757669 (2016) — Selank and GABAergic gene expression / anxiolytic mechanism. https://pmc.ncbi.nlm.nih.gov/articles/PMC4757669/ — retrieved 2026-06-16.
- NCBI / PMC5322660 (2017) — Selank enhances the anxiolytic effect of diazepam under chronic stress. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5322660/ — retrieved 2026-06-16.
- PubMed (2008) — Immunomodulatory effects of selank in patients with anxiety-asthenic disorders. https://pubmed.ncbi.nlm.nih.gov/18577961/ — retrieved 2026-06-16.
- PubMed (2004) — Selank and tuftsin-family peptides in psychopharmacology (review). https://pubmed.ncbi.nlm.nih.gov/14969422/ — 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.