Units to mL Calculator
Convert a dose in international units (U) to a measurable volume in millilitres (mL) using the medication concentration (units/mL). Common for insulin and heparin.
Quick presets (optional)
Choose a common concentration to auto-fill units/mL (e.g., U-100 insulin).
Commas accepted (e.g., 10,000).
Examples: U-100 insulin = 100 units/mL.
For small volumes, follow your syringe/device markings and local protocols.
Safety: Confirm the concentration on the label (e.g., U-100 vs U-40 for insulin; units/mL for heparin) and follow local independent checking policies.
How Units to mL Conversion Works
If a medication is prescribed in units (U) but the product is supplied as a liquid with a labeled concentration in units per mL, you need to calculate the volume to draw up.
The conversion is a simple division:
mL = units ÷ (units/mL)
This is commonly used for insulin (U-100 and U-40) and heparin (various units/mL). Because these are high-risk medicines, always confirm concentration and follow local independent double-check policies.
Quick sanity check: Higher concentration (more units per mL) should give a smaller mL volume for the same unit dose.
Formula
Dose (units): prescribed units to administer
Concentration (units/mL): from the vial/pen label (e.g., U-100 insulin = 100 units/mL)
Worked Examples
Example 1: U-100 insulin. Ordered dose: 25 units. What volume (mL) is required?
Step 1: Dose = 25 units
Step 2: Concentration = 100 units/mL
Step 3: mL = 25 ÷ 100 = 0.25 mL
Example 2: Heparin 5,000 units/mL. Ordered dose: 3,000 units. What volume (mL)?
Step 1: mL = 3000 ÷ 5000 = 0.6 mL
Example 3: U-40 insulin. Ordered dose: 20 units. What volume (mL)?
Step 1: mL = 20 ÷ 40 = 0.5 mL
When This Calculator Is Used
- •Drawing up insulin doses prescribed in units (U)
- •Preparing heparin doses when the vial is labeled units/mL
- •Double-checking volume calculations prior to administration
- •Education: linking “units ordered” to “mL measured”
Clinical safety note: Units-based medicines are high-risk. Always confirm the concentration on the product (especially insulin U-100 vs U-40) and follow local protocols for independent double-checks and device selection.
Related Calculators
Frequently Asked Questions
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.
References & Sources
References support concentration-based dose calculations and high-risk medication safety principles used in unit-based medicines like insulin and heparin.
International
Australia
Clinical Disclaimer: Always verify product labeling and local protocols before preparing or administering medications. This calculator is for educational checking only.