Methodology — How PepCalcs Calculates

Every figure PepCalcs displays comes from the formulas below, applied to values you enter. No value is inferred, assumed or supplied by the site.

Last updated September 1, 2026

1. Unit normalisation

All masses are converted to a single unit before any division occurs.

1 mg = 1000 mcg

1 mcg = 0.001 mg

2. Concentration

Concentration (mg/mL) = vial amount (mg) ÷ diluent volume (mL)

Concentration (mcg/mL) = concentration (mg/mL) × 1000

3. Volume per draw

Dose volume (mL) = target amount (mg) ÷ concentration (mg/mL)

4. Syringe units

PepCalcs reports U-100 units by default because that is the barrel scale most commonly used with reconstituted peptides.

U-100 units = dose volume (mL) × 100

U-40 units = dose volume (mL) × 40

5. Draws per vial

Draws per vial = total vial amount ÷ target amount per draw

6. Nasal spray calculations

For nasal preparations the site uses the widely quoted standard actuation volume of 0.1 mL per spray. Total liquid (extraction volume plus any saline added) is validated against the bottle capacity you select.

Amount per spray = concentration (mg/mL) × 0.1 mL

Sprays per bottle = total liquid volume (mL) ÷ 0.1 mL

7. Volume optimisation

When you ask PepCalcs to optimise, it searches candidate diluent volumes in practical increments and scores them against round target concentrations (for example 5, 10 or 20 mg/mL) and against how readable the resulting draw is on a syringe barrel. It suggests a liquid volume only. It never suggests, adjusts or recommends a research amount.

8. Rounding

Volumes are rounded to two decimal places and syringe units to the nearest readable graduation. Rounding is applied only at display time; intermediate arithmetic uses full floating-point precision.

9. Known limitations

The calculator cannot account for vial overfill, powder displacement volume, or residual liquid left in the needle and hub.
Vial labels are assumed accurate; PepCalcs cannot verify the contents of a vial.
Results are arithmetic only and carry no assessment of suitability, safety or efficacy.