Insulin Units to mL Calculator
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
Convert between insulin units and millilitres for any concentration: U-40, U-100, U-200, U-300, U-500. Critical for correct syringe selection. Educational use only.
🔬 Units ↔ mL Converter
Conversion Result
How to Use the Insulin Units to mL Calculator
- Select your insulin concentration — U-100 is standard; U-40 is mostly veterinary.
- Choose the direction — units → mL, or mL → units.
- Enter the amount and convert. The result shows the volume (or units) with the calculation and a quick-reference table.
Use the volume only with a syringe that matches the concentration. For U-200, U-300 and U-500, dose with the dedicated pen rather than drawing a volume.
Insulin Units to mL Conversion Chart
Volumes for 1 to 1,000 units at the three concentrations people convert most. For U-100 insulin, 1 unit = 0.01 mL, so you move the decimal point two places: 8 units is 0.08 mL and 150 units is 1.5 mL. For U-40, 1 unit = 0.025 mL.
| Insulin units | U-100 volume (mL) | U-40 volume (mL) | U-500 volume (mL) |
|---|---|---|---|
| 1 unit | 0.01 mL | 0.025 mL | 0.002 mL |
| 2 units | 0.02 mL | 0.05 mL | 0.004 mL |
| 3 units | 0.03 mL | 0.075 mL | 0.006 mL |
| 4 units | 0.04 mL | 0.10 mL | 0.008 mL |
| 5 units | 0.05 mL | 0.125 mL | 0.01 mL |
| 6 units | 0.06 mL | 0.15 mL | 0.012 mL |
| 8 units | 0.08 mL | 0.20 mL | 0.016 mL |
| 10 units | 0.10 mL | 0.25 mL | 0.02 mL |
| 12 units | 0.12 mL | 0.30 mL | 0.024 mL |
| 14 units | 0.14 mL | 0.35 mL | 0.028 mL |
| 15 units | 0.15 mL | 0.375 mL | 0.03 mL |
| 18 units | 0.18 mL | 0.45 mL | 0.036 mL |
| 20 units | 0.20 mL | 0.50 mL | 0.04 mL |
| 21 units | 0.21 mL | 0.525 mL | 0.042 mL |
| 25 units | 0.25 mL | 0.625 mL | 0.05 mL |
| 28 units | 0.28 mL | 0.70 mL | 0.056 mL |
| 30 units | 0.30 mL | 0.75 mL | 0.06 mL |
| 35 units | 0.35 mL | 0.875 mL | 0.07 mL |
| 40 units | 0.40 mL | 1.00 mL | 0.08 mL |
| 45 units | 0.45 mL | 1.125 mL | 0.09 mL |
| 50 units | 0.50 mL | 1.25 mL | 0.10 mL |
| 56 units | 0.56 mL | 1.40 mL | 0.112 mL |
| 60 units | 0.60 mL | 1.50 mL | 0.12 mL |
| 70 units | 0.70 mL | 1.75 mL | 0.14 mL |
| 75 units | 0.75 mL | 1.875 mL | 0.15 mL |
| 80 units | 0.80 mL | 2.00 mL | 0.16 mL |
| 100 units | 1.00 mL | 2.50 mL | 0.20 mL |
| 120 units | 1.20 mL | 3.00 mL | 0.24 mL |
| 150 units | 1.50 mL | 3.75 mL | 0.30 mL |
| 200 units | 2.00 mL | 5.00 mL | 0.40 mL |
| 240 units | 2.40 mL | 6.00 mL | 0.48 mL |
| 300 units | 3.00 mL | 7.50 mL | 0.60 mL |
| 500 units | 5.00 mL | 12.50 mL | 1.00 mL |
| 1,000 units | 10.00 mL | 25.00 mL | 2.00 mL |
Large amounts follow the same rule. 300 units of U-100 insulin is 3 mL, the contents of a standard prefilled pen or cartridge, and 1,000 units is 10 mL, a full standard vial.
mL to Insulin Units Chart (reverse)
Going the other way — how many units a given volume holds:
| Volume (mL) | U-100 units | U-40 units |
|---|---|---|
| 0.01 mL | 1 unit | 0.4 units |
| 0.02 mL | 2 units | 0.8 units |
| 0.025 mL | 2.5 units | 1 unit |
| 0.03 mL | 3 units | 1.2 units |
| 0.04 mL | 4 units | 1.6 units |
| 0.05 mL | 5 units | 2 units |
| 0.06 mL | 6 units | 2.4 units |
| 0.08 mL | 8 units | 3.2 units |
| 0.1 mL | 10 units | 4 units |
| 0.12 mL | 12 units | 4.8 units |
| 0.125 mL | 12.5 units | 5 units |
| 0.15 mL | 15 units | 6 units |
| 0.2 mL | 20 units | 8 units |
| 0.25 mL | 25 units | 10 units |
| 0.3 mL | 30 units | 12 units |
| 0.4 mL | 40 units | 16 units |
| 0.5 mL | 50 units | 20 units |
| 0.6 mL | 60 units | 24 units |
| 0.75 mL | 75 units | 30 units |
| 1 mL | 100 units | 40 units |
| 3 mL | 300 units | 120 units |
| 10 mL | 1000 units | 400 units |
Need a value not listed? The converter above handles any amount and any concentration. New to reading a syringe? See How to Read an Insulin Syringe.
Insulin Concentration Explained
The Formula
Example (U-100): 20 units ÷ 100 = 0.2 mL. Example (U-40): 20 units ÷ 40 = 0.5 mL. The same unit dose occupies more volume in a less concentrated insulin.
Concentration mismatches cause the most common dosing errors in this area. Drawing a U-40 dose into a U-100 syringe delivers 2.5 times too little insulin. The syringe calculator marks the exact fill line for a given dose. For pharmacology reference rather than dosing, the units-to-mg converter handles IU-to-milligram conversion, and the dilution calculator covers preparing U-10 or U-50 from U-100 for very small doses.
Common Insulin Concentrations
| Concentration | Units/mL | Common Products | Syringe Required |
|---|---|---|---|
| U-40 | 40 | Vetsulin, Caninsulin (pets) | U-40 syringe |
| U-100 | 100 | Lantus, Levemir, Humalog, NovoLog, Humulin N/R, Novolin N/R | U-100 syringe (standard) |
| U-200 | 200 | Humalog U-200 KwikPen | Pre-measured pen — no syringe drawing |
| U-300 | 300 | Toujeo (glargine 300) | Pre-measured pen — no syringe drawing |
| U-500 | 500 | Humulin R U-500 (severe resistance) | U-500 syringe or dedicated pen |
U-200, U-300, and U-500 insulins are typically dispensed in dedicated pens that dose in units — not drawn up in syringes. Never draw U-300 or U-500 into a standard U-100 syringe. If you must draw from a U-500 vial, use a U-500 syringe or consult your pharmacist for specific instructions.
Reading the Volume on an Insulin Syringe
Syringe sizes and markings
Standard U-100 insulin syringes come in three capacities, and the right one makes small doses easier to read accurately:
| Syringe size | Holds up to | Best for |
|---|---|---|
| 0.3 mL (3/10 cc) | 30 units | Small doses; often has half-unit marks |
| 0.5 mL (1/2 cc) | 50 units | Mid-range doses |
| 1 mL (1 cc) | 100 units | Larger doses (lines often = 2 units) |
Drawing the dose without errors
On a U-100 syringe each numbered line is units, not millilitres, so 30 units is simply the "30" mark — no volume math needed. Draw a little air into the syringe first, inject it into the vial to ease withdrawal, then pull to the unit mark and tap out air bubbles, which otherwise reduce the real dose. Keep the syringe and the insulin at the same concentration.
Insulin Units to mL Calculator: Limitations & Safety Notes
- The conversion depends entirely on concentration. One unit is 0.01 mL of U-100, 0.025 mL of U-40 and 0.002 mL of U-500 — the same unit count gives very different volumes.
- The syringe must match the insulin concentration. A mismatch between U-40 insulin and a U-100 syringe is a well-documented cause of serious dosing error.
- Volumes below roughly 0.05 mL cannot be measured reliably on a standard syringe, so very small doses need a half-unit syringe, a pen or dilution.
- Never draw up a dose from a converted volume without first checking the concentration printed on the vial you are holding.
Unit mistakes are where most dosing errors begin, which is why the full insulin calculator library starts with conversions like this one.
Sources & References
- FDA. Insulin products labeling. Various manufacturers.
- American Diabetes Association. Standards of Care in Diabetes — 2026. Section 9. Link
- Institute for Safe Medication Practices (ISMP). Insulin Safety. Link
Written by Ryan Mitchell · Last updated: October 2026
Frequently Asked Questions: Insulin Units to mL Calculator
How many units are in 1 mL of insulin?
It depends on the concentration. U-100 (the most common human insulin): 100 units/mL. U-40 (e.g., Vetsulin for pets): 40 units/mL. U-200 (Humalog U-200): 200 units/mL. U-300 (Toujeo): 300 units/mL. U-500 (Humulin R U-500): 500 units/mL. Always check the label and use the syringe that matches your concentration.
How do I convert insulin units to mL?
Divide units by concentration: mL = Units ÷ Concentration. For U-100: 20 units ÷ 100 = 0.2 mL. For U-40: 20 units ÷ 40 = 0.5 mL. To convert back: Units = mL × Concentration. Always match the syringe markings to the concentration being used.
What happens if I use a U-100 syringe with U-40 insulin?
Using a U-100 syringe with U-40 insulin causes a 2.5× underdose — you draw what appears to be 25 units on the syringe, but actually contains only 10 units of U-40. Conversely, using a U-40 syringe with U-100 insulin causes a 2.5× overdose — 10 units marked on a U-40 syringe delivers 25 units of U-100. Both errors can be clinically dangerous. This is especially critical for pet owners using Vetsulin (U-40).
What is the most common insulin concentration?
U-100 is the global standard for human insulin — essentially all insulins dispensed in the US, Canada, UK, and Australia for human use are U-100, unless the label specifically states otherwise. Standard insulin syringes sold in pharmacies are U-100. U-40 is used for some veterinary insulins. U-200, U-300, and U-500 are available for specific populations (high-dose, insulin-resistant patients) but are always dispensed with dedicated pens or specific instructions.
How many mL is 50 units of insulin?
For standard U-100 insulin, 50 units is 0.5 mL (50 ÷ 100). At U-40 the same 50 units would be 1.25 mL, and at U-200 it would be 0.25 mL. On a U-100 syringe you simply draw to the "50" mark — no volume conversion needed.
What size insulin syringe do I need?
Match the syringe to your largest usual dose: a 0.3 mL syringe holds up to 30 units (and often has half-unit marks for fine dosing), a 0.5 mL holds up to 50 units, and a 1 mL holds up to 100 units. Smaller syringes make small doses easier to read accurately. All are U-100 — use them only with U-100 insulin.
Is IU the same as a unit of insulin?
Yes. For insulin, IU (international unit), U and "units" all mean the same amount, and some languages write it as UI or IE. So 4 IU of U-100 insulin is 0.04 mL, 20 IU is 0.20 mL and 100 IU is 1 mL. The volume still depends on concentration: 20 IU of U-40 insulin is 0.5 mL.
How many mL is 300 units, and how many units are in a pen or vial?
For U-100 insulin, 300 units is 3 mL and 1,000 units is 10 mL. That matches standard packaging: most prefilled pens and cartridges hold 3 mL (300 units), and a standard vial holds 10 mL (1,000 units). Concentrated pens differ. A Toujeo SoloStar (U-300), for example, holds 450 units in 1.5 mL. Do not draw insulin out of a pen with a syringe unless your care team has told you to.
Can I convert 10,000 or 100,000 units to mL here?
Not with insulin values. Large unit counts such as 4,000, 10,000 or 100,000 usually refer to other medicines, like heparin, vitamin D or penicillin, and each comes in several strengths. Heparin, for example, is sold at 1,000, 5,000 and 10,000 units per mL. Use the concentration printed on that product's label: mL = units ÷ units per mL. Insulin syringes are marked for insulin only, so never use them to measure another medicine.
How many mL is 40 units of insulin added to an IV bag?
For U-100 regular insulin, 40 units is 0.4 mL (40 ÷ 100). This is a common pharmacy and nursing exam question, and for U-100 insulin the answer is always units ÷ 100. In hospital practice, IV insulin is usually prepared by the pharmacy as a standard mix such as 100 units in 100 mL of saline, which gives 1 unit per mL.