Keep mass and volume separate
Milligrams (mg) and micrograms (mcg) describe mass. Milliliters (mL) describe volume. One milligram equals 1,000 micrograms. A concentration connects these quantities: mg/mL tells you the mass in each milliliter.
Understand the U-100 scale
On a U-100 syringe, 100 scale units correspond to 1 mL, so one scale unit represents 0.01 mL. These graduations are a volume scale in this calculator. They do not describe the biological activity of an arbitrary peptide.
International units (IU) describe activity for a particular substance. An IU-to-mg relationship cannot be transferred from one compound to another. Check the substance-specific reference.
Follow a mathematical example
A hypothetical 10 mg sample in 2 mL has a concentration of 5 mg/mL. A 0.5 mg aliquot occupies 0.1 mL, or 10 units on the U-100 scale. Preparing the same sample in 4 mL changes the concentration to 2.5 mg/mL; the same aliquot then occupies 0.2 mL.
Check the physical device
A 30-unit, 50-unit or 100-unit capacity does not by itself tell you the smallest printed graduation. Select the actual graduation in the calculator. A result between markings is displayed without silently changing the target amount.
Try the measurement calculator or use the glossary to look up an unfamiliar term.