How the calculator works
- 1Enter the amount of peptide in the vial, in milligrams, exactly as printed on the label.
- 2Enter the liquid volume used for reconstitution, in millilitres — the amount of diluent you actually added, not the vial's capacity.
- 3Enter the desired amount as a mathematical input: the milligram figure you want converted into a volume.
- 4Select the syringe size and, if you need unit readings, the barrel's unit scale (U-100, U-50 or U-40).
- 5The calculator returns concentration, required volume, equivalent syringe units, how many equal portions of that size the vial theoretically contains, and what remains after the portions you have already drawn.
Frequently asked questions
What is a peptide reconstitution calculator?
A unit converter. It takes the mass of peptide in a lyophilised vial and the volume of diluent added, derives the resulting concentration, and converts a milligram figure into the millilitre volume and syringe-unit reading that correspond to it.
How do you calculate peptide concentration?
Divide the vial amount by the diluent volume. A 10 mg vial reconstituted with 2 mL gives 10 ÷ 2 = 5 mg/mL. The result describes the entire solution, not any single draw.
How do you convert peptide mg to mL?
Divide the milligram figure by the concentration. At 5 mg/mL, 1 mg is 1 ÷ 5 = 0.2 mL. There is no fixed mg-to-mL conversion — it changes with every reconstitution.
How do you convert mL to syringe units?
Multiply the volume by the units per mL printed on the barrel. On U-100, 0.2 mL × 100 = 20 units. On U-40, the same volume is 0.2 × 40 = 8 units.
What does U-100 mean?
It is a calibration standard meaning the barrel is marked so that 100 units equal 1 mL. U-50 and U-40 barrels mark 50 and 40 units per mL respectively. The letter U refers to the scale, not to any property of the liquid inside.
What is the difference between mg and mL?
Milligrams measure how much peptide is present; millilitres measure how much liquid it is dissolved in. Only the ratio between them — the concentration — links the two.
Does changing the liquid volume change peptide concentration?
Yes. The mass of peptide is fixed, so more diluent means a lower concentration and a larger volume for the same milligram figure. Halving the diluent doubles the concentration.
Can this calculator be used for different peptides?
Yes. The arithmetic depends only on mass, volume and syringe calibration, not on which compound is in the vial. The compound-specific pages linked above run the same maths with defaults and context for those compounds.
How much bacteriostatic water should I add to a vial?
Mathematically, any volume works — it only sets the concentration. The diluent calculator above works backwards: choose the milligram figure you want one draw to contain and the unit marking you want it to read, and it returns the reconstitution volume that produces that pairing. Practical limits come from vial capacity, not from the arithmetic.
How do I convert syringe units back to mg or mcg?
Divide the units by the barrel scale to get millilitres, then multiply by the concentration. On a U-100 barrel with a 5 mg/mL solution, 20 units is 20 ÷ 100 = 0.2 mL, and 0.2 × 5 = 1 mg, or 1,000 mcg. The units-to-mg calculator above does this for you.
How many mcg are in 1 mg?
1,000. Milligram figures are multiplied by 1,000 to give micrograms, and microgram figures are divided by 1,000 to give milligrams. Vials are usually labelled in mg while smaller research peptides are often discussed in mcg.
Is this calculator medical dosing advice?
No. It converts numbers you enter. It does not evaluate whether any figure is appropriate for any person, and it makes no treatment recommendation of any kind.
Related pages
- Semaglutide reconstitution calculator — with milligram-to-microgram conversion worked through in detail.
- Tirzepatide reconstitution calculator — including a side-by-side U-100, U-50 and U-40 comparison.
- Retatrutide reconstitution calculator — concentration and volume maths for an investigational compound.
- Peptide reconstitution chart — static lookup tables for common vial sizes, diluent volumes and syringe scales.
- Peptide dosage chart — at-a-glance dosing ranges, half-life and evidence grade for all 20 compounds.
- Peptide database — every profile on the site, searchable by category and evidence grade.
- Storage and reconstitution guide — why lyophilised powder is stable, and what happens once diluent is added.
- Weight loss peptides reference — the metabolic compounds these calculators are most often used with.
Educational and mathematical content only. Nothing on this page is medical advice or a dosing recommendation.