Peptide Dosage Calculator
The general-purpose calculator for any lyophilized research peptide. Enter what is in the vial, how much bacteriostatic water you added, and the amount you want per draw. It returns the solution concentration, the exact mark on a U-100 insulin syringe, and how many draws the vial contains.
- Concentration
- 2500 mcg / mL
- Concentration
- 2.50 mg / mL
- Per syringe unit
- 25.0 mcg / unit
- Draws per vial
- 20.0
- Total solution
- 200 units
Every figure below is arithmetic performed in your browser. Nothing here is a protocol, recommendation, or medical guidance — all Ares Research materials are supplied for in-vitro laboratory research only.
The formula this calculator uses
Concentration is total peptide mass divided by diluent volume: a 5 mg vial in 2 mL of bacteriostatic water gives 2,500 mcg/mL. Draw volume is target amount divided by concentration: 250 mcg ÷ 2,500 mcg/mL = 0.1 mL. Syringe units are draw volume × 100, because a U-100 barrel puts 100 graduations in 1 mL — so 0.1 mL is 10 units. Doses per vial is total mass divided by target amount: 5,000 mcg ÷ 250 mcg = 20.
Why diluent volume changes the syringe mark but not the vial's contents
Adding more bacteriostatic water does not change how much peptide is in the vial — it only changes how spread out it is. A 5 mg vial always contains 5 mg whether you add 1 mL or 5 mL. What changes is the number of units you draw for a given amount: at 1 mL, 250 mcg is 5 units; at 5 mL, the same 250 mcg is 25 units. Larger diluent volumes make small amounts easier to measure accurately because the mark falls further along the barrel.
Choosing a diluent volume for measurement accuracy
A practical rule in laboratory work is to pick the diluent volume that puts your usual draw somewhere between 10 and 50 units on the barrel. Below about 5 units, a half-graduation error is a large percentage of the draw. Above about 60 units, you are using most of the syringe for a single draw and reconstituting more often. This calculator makes the tradeoff visible: change the water volume and watch the unit reading move.
Frequently asked questions
How do I calculate peptide dosage from a vial?
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Divide the total peptide mass in the vial by the volume of bacteriostatic water you added to get the concentration in mcg per mL. Then divide your target amount by that concentration to get the volume to draw in mL, and multiply by 100 to convert that volume into units on a U-100 insulin syringe.
How many units is 250 mcg of a 5 mg vial?
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It depends entirely on the diluent volume. With 5 mg reconstituted in 2 mL, the concentration is 2,500 mcg/mL, so 250 mcg is 0.1 mL — 10 units on a U-100 syringe. Reconstitute the same vial in 1 mL and 250 mcg becomes 5 units; in 5 mL it becomes 25 units.
How do I read a U-100 insulin syringe?
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A U-100 barrel is graduated in units where 100 units equal 1 mL, so each single-unit mark is 0.01 mL. To convert a volume in mL to units, multiply by 100 — 0.25 mL is 25 units. This calculator reports both figures so you can cross-check the mark against the volume.
What is the difference between mg, mcg, and IU?
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A milligram (mg) is 1,000 micrograms (mcg); both are units of mass. An international unit (IU) is not a mass unit at all — it measures biological activity and the mass equivalent differs per compound, so IU cannot be converted to mg without a compound-specific conversion factor. This calculator works entirely in mass units.
How should reconstituted material be stored?
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Once reconstituted, most research peptides are held refrigerated at roughly 2–8°C, protected from light, in the original sealed vial. Bacteriostatic water contains 0.9% benzyl alcohol, which suppresses microbial growth in the diluent. Temperature, light exposure, and repeated freeze-thaw cycles all affect stability, so consult the compound-specific certificate of analysis and published stability data.
Related calculators
Vial mass + diluent volume → mg/mL, mcg/mL, and mcg per syringe unit.
Compare diluent volumes before you mix — see how each one changes the syringe reading.
mL ↔ U-100 units, plus how many mcg each unit carries at your concentration.