U-100 · U-50 · U-40 Insulin Syringe
mg to Units Converter
Enter your working concentration, pick your syringe, and this shows the exact units to draw and the volume in mL for any milligram (or microgram) dose.
Updated June 2026
Use mcg/mL for most peptides, mg/mL for compounded GLP-1.
Draw syringe to
0 units
(0.00 mL)
mg → units on U-100
| Dose (mg) | Volume (mL) | Units (U-100) |
|---|---|---|
| 0.25 mg | — | — |
| 0.5 mg | — | — |
| 1 mg | — | — |
| 1.5 mg | — | — |
| 2 mg | — | — |
| 2.5 mg | — | — |
| 3 mg | — | — |
| 4 mg | — | — |
| 5 mg | — | — |
| 7.5 mg | — | — |
| 10 mg | — | — |
| 15 mg | — | — |
| 20 mg | — | — |
Enter a working concentration to populate the Volume and Units columns.
For educational and research purposes only. This calculator provides estimates based on standard formulas.
Always verify calculations with your healthcare provider before use. We assume no liability for dosing errors, adverse events, or outcomes resulting from use of this tool.
mg to units reference (2.5 mg/mL, U-100)
Common concentration: a 5 mg vial reconstituted with 2 mL BAC water (2.5 mg/mL = 2,500 mcg/mL). Read off your own concentration in the calculator above.
| Dose | Volume (mL) | Units (U-100) |
|---|---|---|
| 0.25 mg | 0.100 | 10 |
| 0.5 mg | 0.200 | 20 |
| 1 mg | 0.400 | 40 |
| 2 mg | 0.800 | 80 |
| 2.5 mg | 1.000 | 100 |
Why you can't convert mg to units without your concentration
Here's the thing that trips everyone up: "units" on an insulin syringe don't measure how much drug you're taking. They measure volume, how far up the barrel the liquid goes. A U-100 syringe just means 100 units equals 1 mL. So 1 mg in a weak solution fills more units than 1 mg in a strong one, even though it's the same dose. That's why there's no single "1 mg equals X units" answer. You have to pin your concentration first, then the units fall out of it.
How the conversion actually works
Two steps, and the calculator does both. First it works out the volume: your dose divided by your concentration. 1 mg at 2.5 mg/mL is 0.4 mL. Then it turns volume into units using your syringe: on a U-100, multiply mL by 100, so 0.4 mL is 40 units. On a U-40 the same 0.4 mL is 16 units. Same dose, same volume, different number on the barrel, because the syringe is scaled differently.
U-100 vs U-50 vs U-40: which syringe are you holding?
Most peptide and GLP-1 users are on U-100 (the standard 1 mL insulin syringe, 100 units to a mL). U-40 syringes are scaled for a more dilute liquid, so the same volume reads as fewer units. U-50 sits in between. The liquid you draw is identical, only the printed scale changes, so the one rule that matters: read the units off the syringe you're actually holding, not someone else's. If you're not sure which you have, it's printed on the barrel.
A quick worked example
Say you reconstituted a 5 mg vial with 2 mL of bacteriostatic water. That's 2.5 mg/mL. You want a 2 mg dose. Volume is 2 ÷ 2.5, which is 0.8 mL. On your U-100 syringe that's 80 units. Want 2.5 mg instead? That's 1.0 mL, the full barrel, or 100 units. Set the concentration once and the whole table updates, so you're not redoing the math every time you change your dose.
If you'd rather not re-derive this every cycle, log your concentration and each dose in Regimen and your draw amount is saved with every shot.
Frequently Asked Questions
How many units is 1 mg on an insulin syringe?
It depends on your concentration. At 2.5 mg/mL (2,500 mcg/mL), 1 mg is 0.40 mL, which is 40 units on a U-100 syringe (or 16 units on a U-40). Set your concentration in the calculator above to get your exact number.
How many units is 2 mg on a 1 mL syringe?
At a common 2.5 mg/mL concentration, 2 mg is 0.80 mL, which is 80 units on a U-100 (1 mL) insulin syringe. At 5 mg/mL it is 40 units. Change the concentration above for your exact figure.
How do you convert mg to insulin units?
Two steps: divide your dose by your concentration to get the volume in mL, then multiply by your syringe factor (100 for U-100, 50 for U-50, 40 for U-40). The calculator does both automatically.
Do units measure the dose or the volume?
Volume. Units are marks on the syringe barrel showing how far up the liquid goes. The same mg dose lands at a different number of units at a different concentration, which is why you set concentration first.
What's the difference between a U-100 and a U-40 syringe?
The scale. A U-100 reads 100 units per mL; a U-40 reads 40 units per mL. The same 0.5 mL of liquid shows as 50 units on a U-100 and 20 units on a U-40. Always read the syringe you're holding.
Can I enter a dose in mcg on this calculator?
Yes. Toggle the dose unit from mg to mcg next to the dose field. The math is identical (1 mg = 1,000 mcg); the toggle only controls how you enter and read the dose row.
How many units is 2.5 mg of tirzepatide?
At 5 mg/mL, 2.5 mg is 50 units on a U-100 syringe. At 10 mg/mL it is 25 units. For the full tirzepatide-specific chart, see the tirzepatide reconstitution calculator linked below.
Working in mcg or units instead? See the units to mL calculator, the units vs mL vs mg explainer, and how to read an insulin syringe.
How to use this calculator
Enter your working concentration
Use mg/mL (e.g. 2.5 mg/mL) or toggle to mcg/mL. This is set by how much BAC water you mixed into the vial.
Pick your syringe
U-100 is the standard 1 mL insulin syringe. U-50 and U-40 use a different scale.
Enter your dose
Type the dose in mg (or toggle to mcg). The calculator returns exact units and mL.
Read the live reference table
Common doses are pre-seeded; the volume and units columns recalculate for your concentration and syringe.
Related Tools
Units to mL Calculator
Reverse direction: convert units on the syringe to volume in mL.
Peptide Reconstitution Calculator
Start from vial size and BAC water — works out your concentration for you.
Tirzepatide Reconstitution Calculator
Tirzepatide-specific reconstitution and dose chart.
GLP-1 Dose Calculator
Multi-compound reconstitution for semaglutide, tirzepatide, retatrutide.
Skip the math every cycle
Regimen saves your concentration with each compound and shows the exact units to draw on every dose log.
- Built-in dose calculators
- Smart injection reminders
- Track weight and side effects
- Private, secure health data
