How to Convert International Units (IU) to micro or milli Grams

How to Convert International Units (IU) to micro or milli Grams

People wonder why the International unit isn't in the lists featured in the mass and weight converter. The reason for this is that the conversion isn't as simple as one might think.

What is an International unit?
IU stands for International units and is a unit commonly used in the measurement of medications, vaccines and vitamins.

The volume or mass that makes up one International unit is dependent on the concentration or potency of the substance and therefore varies from substance to substance depending on what is being measured.

This means that converting between international units and micrograms or milligrams is not a constant or definite  calculation. The exact measure of one IU of a substance is in fact established by international agreement for each substance.

How to find out the conversion value?

If you want to find out how many micrograms (mcg) or milligrams (mg) are in one IU of your medication, you could contact your pharmacist to find out. As an alternative, you could try contacting the drug manufacturer directly. For a vitamin, consider contacting the vitamin manufacturer - their contact information is usually listed on the bottle.

Convertingfrom mg or mcg to IU for Vitamins A, C, D and E

We've included mass equivalents of 1 IU for selected vitamins below. This information is from the Office of the Dietary Supplements and the Ultumate Pharmacy Calculations Guide.

• Vitamin A: 1 IU is the biological equivalent of 0.3 mcg retinol, or of 0.6 mcg beta-carotene
• Vitamin C: 1 IU is 50 mcg L-ascorbic acid
• Vitamin D: 1 IU is the biological equivalent of 0.025 mcg cholecalciferol or ergocalciferol
• Vitamin E: 1 IU is the biological equivalent of about 0.67 mg d-alpha-tocopherol, or 0.9 mg of dl-alpha-tocopherol.

Example
Let's say you have a soft gel capsule that contains 500 IU of Vitamin A as retinol. To convert this to mcg, using the information above, you would multiply it by 0.3:

500 × 0.3 = 150mcg.

Conversely, if the soft gel capsule was described as '150mcg of Vitamin A as retinol' and you wanted to convert to IU, divide it by 0.3.

150 ÷ 0.3 = 500 IU.


Note that the information contained here is purely for casual interests and is not intended to replace your doctor's advice. Please use it at your own risk. As with all calculations where health could suffer from inaccurate conversions, you are advised to check with a health professional before taking a dosage of any vitamin or supplement.

Additional Recources
A vitamin converter is available on the RFA Regulatory Affairs Website.


-The Calculators Site

This is Teach, Learn and Connect! 

-AdminT