Convert units to cc (mL) from the label concentration, such as U-100 insulin, or convert cc to units. Arithmetic only; confirm any dose with a clinician.
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Calculator Functions
| Function | What it does | What it requires |
|---|---|---|
| Units to cc (volume) | Converts an amount in units or IU to a volume in cc, mL or µL | Requires the amount in units and the labeled concentration in units/mL |
| cc to units | Finds how many units a known volume contains | Requires the volume in cc, mL or µL and the labeled concentration in units/mL |
| Concentration from units and volume | Finds the concentration in units/mL from an amount and the volume that holds it | Requires the amount in units and the volume in cc, mL or µL |
The labeled concentration starts at U-100, with U-40, U-200, U-300, U-500 and a custom units/mL value as the other choices. Every result lists the amount, the concentration and the volume in both mL and cc. Display settings limit the answer to 2, 4 or 6 decimals.
Units to cc Formulas
| V | Volume in cc. One cc is one cubic centimeter, which is the same volume as 1 mL [1][2] |
| U | Amount in units or IU |
| C | Concentration printed on the product label (units/mL). The number after “U-” is this figure: U-100 is 100 units/mL [3] and U-500 is 500 units/mL [4] |
Units have no fixed volume. The same 20 units is 0.2 cc of a U-100 product and 0.04 cc of a U-500 product, so the concentration has to come from the label of the exact product in hand.
Units to cc (volume)
The amount is divided by the concentration. At U-100, 20 units is 20 ÷ 100 = 0.2 cc, 100 units is 1 cc and 1 unit is 0.01 cc. The result can also be shown in mL, which is the same number, or in µL, which is 1,000 times larger.
Units to cc Conversion Chart
| Units | cc at U-100 | cc at U-40 | cc at U-500 |
|---|---|---|---|
| 1 | 0.01 | 0.025 | 0.002 |
| 5 | 0.05 | 0.125 | 0.01 |
| 10 | 0.1 | 0.25 | 0.02 |
| 20 | 0.2 | 0.5 | 0.04 |
| 25 | 0.25 | 0.625 | 0.05 |
| 30 | 0.3 | 0.75 | 0.06 |
| 40 | 0.4 | 1 | 0.08 |
| 50 | 0.5 | 1.25 | 0.1 |
| 100 | 1 | 2.5 | 0.2 |
The chart is arithmetic only. A dose written in mg is a different conversion, because it depends on the product’s mg/mL strength. The mg to cc Converter covers that case.
cc to units
The volume in mL is multiplied by the concentration. At U-100, 0.2 cc holds 0.2 × 100 = 20 units and a full 1 cc holds 100 units. At U-40, 0.5 mL holds 20 units. A volume entered in µL is divided by 1,000 first.
Concentration from units and volume
The amount is divided by the volume in mL. A 3 mL pen that contains 1,500 units works out to 1,500 ÷ 3 = 500 units/mL, which is the U-500 strength [4].
Limits of This Estimate
- The result is arithmetic. It does not set a dose, and a pharmacist or clinician should confirm the prescribed dose, the exact product and the delivery device.
- The markings on an insulin syringe are made for one concentration. A U-100 vial is labeled for use only with a U-100 syringe [3], and measuring U-500 insulin in a U-100 syringe can give a 5 times overdose [4]. A calculated volume is not a syringe marking.
- A concentrated insulin pen shows the dose in units and needs no conversion. The U-500 pen label says not to transfer its insulin into any syringe, because overdose and severe hypoglycemia can result [4].
- U-40, U-200 and U-300 are listed as concentration examples, not as interchangeable products. A very small answer, such as 0.002 cc, may be too small to measure with a given device.
Sources
- NIST, Guide for the Use of the International System of Units (SP 811), Chapter 5, Table 6: 1 L equals 1 cubic decimeter, so 1 mL equals 1 cubic centimeter
- NIST, Guide for the Use of the International System of Units (SP 811), Section 6.1.8: cc as an abbreviation for cubic centimeter
- U.S. National Library of Medicine, DailyMed, Humulin R (insulin human) injection label: U-100 as 100 units/mL and the U-100 syringe instruction, as of the label published September 7, 2026
- U.S. National Library of Medicine, DailyMed, Humulin R U-500 (insulin human) injection label: U-500 as 500 units/mL, the 3 mL pen with 1,500 units, the syringe overdose warning and the pen transfer warning, as of the label published September 2, 2026
