Enter the vitamin D amount in IU into the calculator to convert it to micrograms (mcg), or use the formula below to convert IU to mcg manually.
Quick overview: Vitamin D IU to mcg
Vitamin D supplements are often labeled in IU, while dietary recommendations may use micrograms (mcg). For both vitamin D2 and vitamin D3, the conversion is the same: 1 IU = 0.025 mcg and 1 mcg = 40 IU.
- 400 IU = 10 mcg
- 600 IU = 15 mcg
- 800 IU = 20 mcg
- 1,000 IU = 25 mcg
This calculator applies the standard factor automatically for vitamin D2, vitamin D3, and unspecified vitamin D.
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Vitamin D IU to mcg Formula
The following formula is used to convert vitamin D from international units (IU) to micrograms (mcg).
mcg = IU × 0.025 = IU / 40
Variables:
- mcg is the amount of vitamin D in micrograms
- IU is the amount of vitamin D in international units
To convert vitamin D from IU to mcg, multiply the IU value by 0.025 or divide it by 40.
What is Vitamin D IU to mcg Conversion?
Vitamin D dosage can be listed in either international units (IU) or micrograms (mcg). IU measures biological activity, while mcg measures mass. For vitamin D, health and nutrition references use a fixed relationship: 1 IU = 0.025 mcg and 1 mcg = 40 IU. Because this factor is constant, converting between IU and mcg is straightforward.
This same conversion applies to vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). For example, 800 IU of vitamin D equals 20 mcg, and 2,000 IU equals 50 mcg.
How to Convert Vitamin D IU to mcg?
The following steps outline how to convert vitamin D from IU to mcg.
- First, determine the vitamin D amount in international units (IU).
- Next, use the standard conversion factor of 0.025 mcg per IU.
- Multiply the IU value by 0.025, or divide the IU value by 40.
- After calculating the result, check your answer with the converter above.
Example Problem:
Use the following values as an example problem to test your knowledge.
Vitamin D Amount (IU) = 800
Micrograms (mcg) = 800 × 0.025 = 20 mcg
Vitamin D IU to mcg Conversion Table
The table below lists common vitamin D doses in IU along with their equivalent values in mcg.
| Vitamin D Dose (IU) | Dose in mcg | Notes |
|---|---|---|
| 400 IU | 10 mcg | 400 × 0.025 = 10 |
| 600 IU | 15 mcg | 600 × 0.025 = 15 |
| 800 IU | 20 mcg | 800 × 0.025 = 20 |
| 1,000 IU | 25 mcg | 1,000 × 0.025 = 25 |
| 2,000 IU | 50 mcg | 2,000 × 0.025 = 50 |
| 4,000 IU | 100 mcg | 4,000 × 0.025 = 100 |
| 10,000 IU | 250 mcg | 10,000 × 0.025 = 250 |
Different regions, supplement labels, and dietary references may use either IU or mcg for vitamin D. Since the conversion factor is fixed, knowing that 1 mcg = 40 IU makes it easy to compare dosages across labels and recommendations.