Math & Measurement
Milliliter (mL)
Also called: mL, ml
Definition
A metric unit of liquid volume equal to one-thousandth of a liter.
What Milliliter (mL) means
Milliliters describe liquid volume. BAC water volume, draw volume, and syringe capacity are all commonly expressed in mL.
Why the distinction matters
On a U-100 insulin syringe, 1 mL corresponds to 100 syringe units, but that relationship is a volume scale rather than a statement about drug mass.
Common confusion
mL is a volume unit. A specific mL amount can contain very different masses depending on concentration.
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Open the BACToBasics tools and reference pages where this term is used.
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Related glossary terms
Math & Measurement
U-100 Syringe Units
Volume markings on a U-100 insulin syringe where 100 units correspond to 1 mL of liquid.
Math & Measurement
Concentration
The amount of a substance contained in a given volume of liquid, such as mg/mL or mcg/mL.
Reconstitution & Vials
Bacteriostatic Water
Sterile water for injection that contains an antimicrobial preservative intended to inhibit bacterial growth after entry into the vial.
Published September 6, 2026. BACToBasics glossary pages are educational definitions only and do not provide medical, dosing, preparation, treatment, or product-selection advice.