Guide
Convert mg to units on a U-100 syringe.
Milligrams and syringe units are not the same thing. The concentration of the liquid is what connects them.
Vialist does arithmetic on numbers you give it. It does not give dosing advice. Every example here is for illustration only, so use the dose your prescriber gave you and the instructions on your product label or from your pharmacist.
What a unit is
A U-100 insulin syringe holds 100 units in 1 mL, so 1 unit is 0.01 mL. Units measure volume. Milligrams measure how much compound is in that volume. A 10-unit draw is always 0.1 mL, but how many mg that is depends on the concentration in the vial.
The formula
units = dose in mg ÷ concentration in mg per mL × 100
If your dose is in mcg, divide by 1000 first, because 1000 mcg is 1 mg. For example, 250 mcg is 0.25 mg. If the vial is labeled in IU, see the hCG units calculator, because IU cannot be converted to mg.
Worked example. A concentration of 5 mg per mL and an example amount of 0.5 mg gives 0.5 ÷ 5 = 0.1 mL, and 0.1 × 100 = 10 units. Example only. Use the dose your prescriber gave you.
Table of examples
The amounts and the three concentrations are arbitrary examples chosen to show the arithmetic. They are not doses. Find the concentration on your own label, or work it out from the vial amount and the water you added (see how to reconstitute a vial).
| Amount (mg) | 2.5 mg/mL | 5 mg/mL | 10 mg/mL |
|---|---|---|---|
| Units | Units | Units | |
| 0.1 | 4 | 2 | 1 |
| 0.25 | 10 | 5 | 2.5 |
| 0.5 | 20 | 10 | 5 |
| 1 | 40 | 20 | 10 |
| 2.5 | 100 | 50 | 25 |
Each cell is computed by the same code as the calculators. At the same amount, a higher concentration means fewer units.
Other syringe scales
The same mL reads differently on other scales. This table shows how many mL a number of units is on each syringe type.
| Units | U-100 (mL) | U-50 (mL) | U-40 (mL) |
|---|---|---|---|
| 5 | 0.05 | 0.1 | 0.125 |
| 10 | 0.1 | 0.2 | 0.25 |
| 20 | 0.2 | 0.4 | 0.5 |
| 25 | 0.25 | 0.5 | 0.625 |
| 50 | 0.5 | 1 | 1.25 |
| 100 | 1 | 2 | 2.5 |
Check the markings on the syringe you are using. More detail is on the units to mg page.
Check before you draw
- Confirm the syringe says U-100.
- Use the concentration on your label, not one from a table.
- Compare the result with the pharmacy label, or ask your pharmacist to check it with you.
Related calculators
- Doses left in a vial calculator
- The general reconstitution calculator
- Semaglutide units calculator
- Tirzepatide units calculator
- Retatrutide units calculator
- Tesamorelin units calculator
- hCG units calculator (IU)
- Testosterone cypionate mg to mL calculator
- Units to mg: how many units is 0.25 mg?
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- How to reconstitute a vial: the math
- How long does a mixed vial last?
- Injection sites and rotation
- How to track peptide injections
- All guides
Vialist Log does this automatically
Vialist does the conversion for you. It shows the units to draw for the dose you enter, with the mg and the mL underneath, and it never asks you to do the arithmetic by hand.