PeptideWise

Syringe Unit Converter

Converts between milligrams, micrograms, milliliters, and insulin syringe units for reconstituted peptides. Supports U-100, U-50, U-40, and U-30 syringes. All output values are estimates based on standard volumetric formulas.

Peptide amount in vial
Bacteriostatic water added (mL)
Desired dose per injection
Syringe type

Estimated draw

Reconstituted concentration
2500 mcg / mL
Units to draw on U-100
10.0 units

Equivalent to 0.100 mL

Dose
250 mcg

These figures are estimates based on standard formulas. Always verify with your prescriber and the peptide compounding label.

How the conversion works

Reconstituted peptide concentration is the labeled mass divided by the bacteriostatic water volume. For a 5 mg vial reconstituted with 2 mL of bacteriostatic water, concentration is 2,500 mcg/mL. A 250 mcg dose at that concentration is 0.10 mL — which on a U-100 syringe is 10 units.

On U-100, U-50, and U-30 insulin syringes, 100 units always equals 1 mL — the smaller barrel size limits the maximum draw, not the unit scale. On U-40 syringes, 40 units equals 1 mL, so the same 0.10 mL draw shows as 4 units.

Limitations

  • Estimates assume the labeled vial mass is exact. Manufacturing tolerance is typically 5-10%.
  • Dead volume in the syringe and needle (~0.05 mL on a 1 mL insulin syringe) is not accounted for.
  • Bacteriostatic water volume displaces a tiny amount of the lyophilized peptide volume; this calculator treats peptide volume as negligible.
  • For informational purposes only. Not a substitute for professional medical advice.

Sources

  1. USP <797> Pharmaceutical Compounding — Sterile Preparations. United States Pharmacopeia.
  2. Insulin Administration: Standards of Medical Care. American Diabetes Association.

Frequently Asked Questions

What does "units" mean on an insulin syringe?
An insulin syringe is marked in "units" rather than mL because it was designed for insulin dosing. On a U-100 syringe, 100 units equals 1 mL — so 10 units equals 0.10 mL. On a U-40 syringe, 40 units equals 1 mL. The "U" number tells you how many units the manufacturer printed on the 1 mL line.
How do I know what concentration my vial is?
Concentration depends on how much bacteriostatic water you add to a lyophilized peptide vial. A 5 mg peptide vial reconstituted with 2 mL of bacteriostatic water yields a 2,500 mcg/mL (or 2.5 mg/mL) solution. This calculator computes that concentration for you so you can convert it to syringe units.
Why are U-100, U-50, and U-30 syringes scaled differently from U-40?
U-100, U-50, and U-30 syringes all use the 100-units-per-mL scale — the "50" or "30" is the printed barrel length in units, not a different scale. U-40 syringes are different: they use 40 units per mL, an older standard still used in some countries. Always check the box before drawing.
What if my draw exceeds the syringe capacity?
If the calculator flags "exceeds syringe capacity," either choose a larger syringe (e.g. switch from U-30 to U-100), reconstitute the vial with more bacteriostatic water to lower concentration, or split the dose into two injections. Never overdraw a syringe.
Is this calculator a substitute for a pharmacist or prescriber?
No. This tool provides unit-conversion estimates based on standard formulas. It does not account for vial overfill, manufacturer tolerance, dead volume, or your individual clinical situation. Always verify with your prescriber and the peptide compounding label.