Reading an Insulin Syringe: Units vs mL
On a standard U-100 insulin syringe, 100 units equal 1 mL, so each unit is 0.01 mL. To convert a dose volume to units, multiply the millilitres by 100. Insulin syringes come in 0.3 mL (30 units), 0.5 mL (50 units), and 1 mL (100 units) sizes; smaller barrels give finer, more accurate marks for small draws.
For educational and research purposes only. Not medical advice. Always consult a licensed healthcare professional before starting any protocol.
What a unit means
Insulin syringes are marked in units rather than millilitres. The near-universal standard is U-100, which means the scale assumes 100 units per millilitre. On that scale one unit equals 0.01 mL. This is a volume marking, not a measure of how much peptide is present, so units only tell you dose once you know the concentration of your solution.
That distinction trips people up. Two syringes both drawn to 10 units contain the same volume, 0.1 mL, but the actual milligrams of peptide depend entirely on how concentrated each solution is.
Converting between units and mL
The conversion is simple arithmetic on the U-100 scale. To go from volume to units, multiply millilitres by 100: 0.1 mL is 10 units, 0.25 mL is 25 units. To go the other way, divide units by 100: 20 units is 0.2 mL. Because the peptide dose is set in milligrams, the usual workflow is dose to volume to units, using the concentration in the middle step.
Choosing a syringe size
Insulin syringes typically come in three barrel sizes: 0.3 mL (30 units), 0.5 mL (50 units), and 1 mL (100 units). The smaller the barrel, the more spread out the markings, which makes small draws easier to measure accurately. For tiny GLP-1 or peptide draws of a few units, a 0.3 mL syringe is usually the most precise choice.
If a dose needs more volume than a syringe can hold, you have overdrawn it. The fix is to pick a larger syringe, split the dose across two injections, or reconstitute with more water so the same dose occupies fewer units.
Frequently asked questions
How many mL is 10 units?
On a U-100 insulin syringe, 10 units is 0.1 mL, because 100 units equal 1 mL. Multiply units by 0.01 to get millilitres.
How do I convert a dose in mg to units?
First divide your dose in mg by the concentration in mg/mL to get the volume in mL, then multiply that volume by 100 to get units. The calculator does this and shows the draw on a to-scale syringe.
Which insulin syringe size should I use?
A 0.3 mL (30-unit) syringe gives the finest markings and is best for small draws. Use a 0.5 mL or 1 mL syringe when a dose needs more volume than a smaller barrel can hold.
What does U-100 mean?
U-100 means the syringe scale is calibrated for 100 units per millilitre. Almost all insulin syringes are U-100, so each unit represents 0.01 mL of liquid.
Related tools
Peptide & GLP-1 Dose Calculator
Free lab-grade calculator for peptide reconstitution and GLP-1 dosing. Calculate your exact dose and see it rendered on a to-scale insulin syringe — semaglutide, tirzepatide, BPC-157 and more.
GLP-1 Dose & Titration Calculator
Free dose calculator for semaglutide and tirzepatide. Get a week-by-week titration schedule with the exact units to draw on a to-scale insulin syringe.