How many mL is 10 units?

On a U-100 insulin syringe, 10 units is 0.1 mL. The rule is that 100 units is 1 mL, so dividing the units by 100 gives millilitres. On a U-40 syringe the same 10 units is 0.25 mL.

How many units is 0.5 mL?

50 units on a U-100 syringe, and 20 units on a U-40 one.

Is a 0.5 mL syringe the same as a U-50 syringe?

They are usually the same thing described two ways, and the naming causes real confusion. A 0.5 mL insulin syringe holds 50 units because it is calibrated U-100 and half a millilitre is half of 100 units. The barrel size is not a different scale. U-40 is a different scale, and that is the one to watch for.

Does the barrel size change the conversion?

No. A 0.3 mL, a 0.5 mL and a 1 mL insulin syringe are all calibrated the same way, so 20 units is 0.2 mL on all three. What changes is how much the barrel holds and how finely it is printed.

Syringe Units Calculator

Converts to

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Enter a figure to convert.

The rule: –

On the barrel

This works out the arithmetic for the figures you enter. It does not recommend doses and does not know what is in your vial.

The conversion

U-100: mL = units ÷ 100 · U-40: mL = units ÷ 40

A syringe's calibration is the number of units it calls one millilitre, and it is a property of the printing rather than of the barrel. U-100 is the standard everywhere insulin is sold in the US, so unless the barrel says otherwise, 100 units is 1 mL and a unit is a hundredth of a millilitre.

Units to mL

Units	On a U-100 syringe	On a U-40 syringe
1 units	0.01 mL	0.025 mL
2 units	0.02 mL	0.05 mL
5 units	0.05 mL	0.125 mL
10 units	0.1 mL	0.25 mL
15 units	0.15 mL	0.375 mL
20 units	0.2 mL	0.5 mL
25 units	0.25 mL	0.625 mL
30 units	0.3 mL	0.75 mL
40 units	0.4 mL	1 mL
50 units	0.5 mL	1.25 mL
75 units	0.75 mL	1.875 mL
100 units	1 mL	2.5 mL

mL to units

Volume	On a U-100 syringe	On a U-40 syringe
0.05 mL	5 units	2 units
0.1 mL	10 units	4 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
0.5 mL	50 units	20 units
0.75 mL	75 units	30 units
1 mL	100 units	40 units

Barrel size is not a different scale

This trips people up constantly, partly because the syringes are sold under both names. A 0.3 mL insulin syringe is often called a 30 unit; a 0.5 mL is called a 50 unit; a 1 mL is called a 100 unit. Those are the same fact stated twice, because all three are calibrated at 100 units to the millilitre.

So switching from a 0.5 mL barrel to a 1 mL barrel does not change what 20 units means. It changes how much the syringe holds, and it changes how finely the barrel is printed, which is why a small dose is easier to draw accurately on a smaller barrel. Theinsulin syringe guide covers the graduations.

U-40 is the genuine exception and the one worth checking for. It is a different calibration, not a different size, and on it the same millilitre reads as 40 units.

Questions

How many mL is 10 units?: On a U-100 insulin syringe, 10 units is 0.1 mL. The rule is that 100 units is 1 mL, so dividing the units by 100 gives millilitres. On a U-40 syringe the same 10 units is 0.25 mL.
How many units is 0.5 mL?: 50 units on a U-100 syringe, and 20 units on a U-40 one.
Is a 0.5 mL syringe the same as a U-50 syringe?: They are usually the same thing described two ways, and the naming causes real confusion. A 0.5 mL insulin syringe holds 50 units because it is calibrated U-100 and half a millilitre is half of 100 units. The barrel size is not a different scale. U-40 is a different scale, and that is the one to watch for.
Does the barrel size change the conversion?: No. A 0.3 mL, a 0.5 mL and a 1 mL insulin syringe are all calibrated the same way, so 20 units is 0.2 mL on all three. What changes is how much the barrel holds and how finely it is printed.