mL to Insulin Units Calculator
Enter a volume in millilitres and select your insulin concentration to calculate the equivalent dose in insulin units.
How to Use This Calculator
- Enter the volume in millilitres (mL).
- Select the insulin concentration — U-100 is standard; U-40 is mostly veterinary.
- Convert to read the equivalent dose in units, with the calculation shown.
Confirm the "U-number" on your vial or pen first — the same volume holds very different units at different concentrations. Always draw with the matching syringe.
Quick Reference
| Volume (mL) | U-40 units | U-100 units | U-200 units |
|---|---|---|---|
| 0.1 mL | 4 units | 10 units | 20 units |
| 0.25 mL | 10 units | 25 units | 50 units |
| 0.5 mL | 20 units | 50 units | 100 units |
| 1.0 mL | 40 units | 100 units | 200 units |
Converting mL Back Into Units
Most insulin is dosed in units, but you sometimes need the reverse — turning a volume in millilitres back into units — when reading a syringe, drawing from a vial of unusual concentration, or checking a veterinary dose. The math is a single multiplication: units = mL × concentration, where concentration is the number after the "U" on the label.
Concentration is everything here. The same 0.5 mL is 50 units of U-100 insulin but only 20 units of U-40 — so always confirm the "U-number" on the vial before converting, and use the matching syringe.
When and Why You'd Convert mL to Units
Common situations
Most people dose in units, but the reverse conversion is useful when reading a partly-filled syringe, checking a leftover volume in a vial, working from an older prescription written in mL, or confirming a veterinary dose on an unusual concentration.
The pet-insulin trap (U-40 vs U-100)
Many pet insulins — Vetsulin / Caninsulin — are U-40, not U-100. Drawing U-40 insulin into a U-100 syringe under-doses the animal by 2.5×, and the reverse over-doses. Always use the U-40 syringe that matches U-40 insulin, and only use this converter to double-check, never to substitute the wrong syringe.
Frequently Asked Questions
How do I convert mL to insulin units?
Multiply the volume in mL by the insulin's concentration. For U-100 insulin, 0.5 mL × 100 = 50 units. For U-40 insulin, 0.5 mL × 40 = 20 units.
How many units is 1 mL of insulin?
It depends on concentration. 1 mL of U-100 insulin is 100 units; 1 mL of U-40 is 40 units; 1 mL of U-200 is 200 units. The concentration is printed on the vial or pen.
How many units is 0.5 mL of insulin?
For standard U-100 insulin, 0.5 mL is 50 units. For U-40 it is 20 units, and for U-200 it is 100 units.
Why does concentration matter when converting mL to units?
Because units measure insulin activity, not volume. Two vials of the same size can hold very different total units, so the same mL contains different units depending on whether the insulin is U-40, U-100, or U-200. Always match the syringe to the concentration.
How many units is 0.3 mL of insulin?
For standard U-100 insulin, 0.3 mL is 30 units (0.3 × 100). At U-40 it would be 12 units, and at U-200 it would be 60 units. Always check the concentration printed on the vial or pen before relying on the number.
My pet's insulin is U-40 — how do I measure it correctly?
Use a U-40 syringe with U-40 insulin (such as Vetsulin or Caninsulin) — the markings then read the correct units directly. Don't use a U-100 syringe with U-40 insulin, as it under-doses by 2.5×. If you only have the volume, multiply by 40 to get the units, then confirm the dose and syringe with your vet.
Reference
- Insulin vial and pen labeling (U-40, U-100, U-200, U-500 concentrations).
Last reviewed: June 2025