mcg to IU Converter – Convert International Units to mcg or mg

1 mcg of vitamin A is equal to 3.33 IU, use mcg to IU converter to convert measurements between micrograms (mcg) and International Units (IU).

This conversion is particularly important in the fields of nutrition, pharmaceuticals, and dietary supplements, where both units are commonly used to express the potency or concentration of various substances.

Micrograms (mcg) are a metric unit of mass, where 1 mcg is equal to one millionth of a gram. The International Units (IU) are a standardized measurement of biological activity or effect for vitamins and drugs.

The relationship between mcg and IU varies depending on the specific substance being measured, as IU is not a fixed unit of mass but rather a measure of potency.

• Vitamin A: Commonly measured in both mcg RAE (Retinol Activity Equivalents) and IU.
• Vitamin D: Often listed in both mcg and IU on supplement labels.
• Vitamin E: Measured in mg or IU, but can be converted to mcg.
• Vitamin K: Sometimes measured in mcg or IU.
• Biotin: A B-vitamin that can be measured in both mcg and IU.
• Folate: While typically measured in mcg DFE (Dietary Folate Equivalents), it’s occasionally expressed in IU.
• Some hormones: Such as insulin or certain growth factors.
• Certain medications: Particularly some antibiotics and vaccines.

mcg to IU Conversion Formula

IU = mcg × conversion factor

Conversely, to convert from IU to mcg:

mcg = IU ÷ conversion factor

For example, the conversion factor for vitamin D is different from that of vitamin A or vitamin E.

The conversion between mcg and IU is not universal and depends on the specific substance being measured.

Common substances that use mcg to IU conversions include vitamins like Vitamin A, Vitamin D, and Vitamin E.

Here are the conversion factors for these vitamins:

• Vitamin A: 1 IU = 0.3 mcg (retinol) or 1 IU = 0.6 mcg (beta-carotene)
• Vitamin D: 1 IU = 0.025 mcg (cholecalciferol)
• Vitamin E: 1 IU = 0.67 mcg (d-alpha-tocopherol) or 1 IU = 0.9 mcg (dl-alpha-tocopherol)

Using these conversion factors, here are the conversions for the given values:

Vitamin A (retinol)

1 IU = 0.3 mcg

• 400 mcg = 1333.33 IU
• 900 mcg = 3000 IU
• 2.5 mcg = 8.33 IU
• 23 mcg = 76.67 IU
• 100 mcg = 333.33 IU
• 125 mcg = 416.67 IU
• 50 mcg = 166.67 IU
• 1000 mcg = 3333.33 IU

Vitamin D

1 IU = 0.025 mcg

• 400 mcg = 16000 IU
• 900 mcg = 36000 IU
• 2.5 mcg = 100 IU
• 23 mcg = 920 IU
• 100 mcg = 4000 IU
• 125 mcg = 5000 IU
• 50 mcg = 2000 IU
• 1000 mcg = 40000 IU

Vitamin E (d-alpha-tocopherol)

1 IU = 0.67 mcg

• 400 mcg = 597.01 IU
• 900 mcg = 1343.28 IU
• 2.5 mcg = 3.73 IU
• 23 mcg = 34.33 IU
• 100 mcg = 149.25 IU
• 125 mcg = 186.57 IU
• 50 mcg = 74.63 IU
• 1000 mcg = 1492.54 IU

How many mcg are in an IU?

Here are some common examples:

• Vitamin D: 1 IU = 0.025 mcg
• Vitamin A: 1 IU = 0.3 mcg
• Vitamin E: 1 IU = 0.67 mcg (for natural vitamin E)

These conversions highlight the importance of knowing the specific substance when performing mcg to IU calculation.

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What is 100 mcg in IU?

To convert 100 mcg to IU, we use vitamin D as an example:

For vitamin D: 1 IU = 0.025 mcg

Therefore, 100 mcg = 100 ÷ 0.025 = 4000 IU.

So, 100 mcg of vitamin D is equivalent to 4000 IU.

What is 2000 IU to mcg?

Again, let’s use vitamin D for this conversion:

For vitamin D: 1 IU = 0.025 mcg

2000 IU = 2000 × 0.025 = 50 mcg.

2000 IU of vitamin D is equivalent to 50 mcg.

Does 1000 IU equal 25 mcg?

This question is specifically true for vitamin D:

1000 IU of vitamin D = 1000 × 0.025 mcg = 25 mcg.

For vitamin D, 1000 IU does indeed equal 25 mcg. It’s important to remember that this equivalence is specific to vitamin D and does not apply to other substances.

mcg to IU Conversion Table

Substance	mcg	IU	Conversion Factor
Vitamin D	10 mcg	400 IU	1 IU = 0.025 mcg
Vitamin D	25 mcg	1000 IU	1 IU = 0.025 mcg
Vitamin A	300 mcg	1000 IU	1 IU = 0.3 mcg
Vitamin A	900 mcg	3000 IU	1 IU = 0.3 mcg
Vitamin E	10 mg	14.9 IU	1 IU = 0.67 mg
Vitamin E	15 mg	22.4 IU	1 IU = 0.67 mg

Sample calculations:

1. Vitamin D:
   • 10 mcg to IU: 10 ÷ 0.025 = 400 IU
   • 1000 IU to mcg: 1000 × 0.025 = 25 mcg
2. Vitamin A:
   • 300 mcg to IU: 300 ÷ 0.3 = 1000 IU
   • 3000 IU to mcg: 3000 × 0.3 = 900 mcg
3. Vitamin E (note: typically measured in mg, 1 mg = 1000 mcg):
   • 10 mg to IU: 10 ÷ 0.67 = 14.9 IU
   • 22.4 IU to mg: 22.4 × 0.67 = 15 mg