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The Calculator

Peptide Calculator

ByThe InjectCompass Editorial TeamUpdatedApril 21, 20268 min read

Enter the amount of peptide in your vial, the volume of bacteriostatic water you are adding, and your target dose. The calculator returns the number of units to draw on a U-100 insulin syringe, and the visual syringe highlights the exact tick mark.

Peptide dose calculator

Inputs

Enter peptide amount in milligrams, bacteriostatic water volume in millilitres, and target dose in micrograms. Output updates automatically.

Output

Concentration
2.5 mg/mL
Units per dose
10
mL per dose
0.1 mL
Doses per vial
20
Rounding error
0%
010203040506070809010010U-100 insulin syringe · 100 units = 1 mL

Verify with your prescriber before administering.

This calculator is an educational reference tool. It is not medical advice, a dose recommendation, or a prescription. Math is unit-tested and conservative, but any human administration must be verified against your prescriber's instructions and the manufacturer package insert.

How it works

The math behind the calculator

A peptide vial contains a dry powder that has to be reconstituted with bacteriostatic water before it can be drawn into a syringe. Once reconstituted, the concentration equals the dry mass divided by the volume of diluent added. This is the standard dilution identity described in the USP <797> compounded sterile preparation reference.

On a U-100 insulin syringe, 100 units equals 1 millilitre. The number of units to draw for a given dose equals the target dose divided by the concentration, then scaled to the U-100 graduation.

concentration (mg/mL) = peptide_mg ÷ bac_water_mL
mL_per_dose = dose_mcg ÷ (concentration × 1000)
units_per_dose = mL_per_dose × 100
Worked example

5 mg vial, 2 mL diluent, 250 mcg target dose

  • Concentration: 5 mg ÷ 2 mL = 2.5 mg/mL = 2,500 mcg/mL
  • Volume per dose: 250 mcg ÷ 2,500 mcg/mL = 0.1 mL
  • Units per dose: 0.1 mL × 100 = 10 units on a U-100 insulin syringe
Rounding convention

Rounded to the nearest whole unit

U-100 insulin syringes do not subdivide below 1 unit, so the calculator rounds to the nearest whole unit. The unrounded value appears as a secondary figure. If rounding introduces more than a 2% dose error, the calculator displays a warning and suggests adjusting the bacteriostatic water volume to bring the dose onto a cleaner tick mark.

When the output looks wrong

Edge cases the calculator flags

  • If units > 100, the whole dose cannot be drawn on a single U-100 syringe. Reconstitute with less diluent, or split the dose.
  • If units round to 0, concentration is too low. Reconstitute with less diluent.
  • If rounding error > 2%, adjust bac water volume by 0.1–0.5 mL to land on a cleaner mark.
  • If concentration > 50 mg/mL, double-check inputs. That is unusually high.
Related references

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