Vitamin D3 (Cholecalciferol)
Vitamin D3 is crucial for bone health, immune function, and calcium absorption. 1 IU = 0.025 mcg.
Data verified against NIHLast verified: 2026-02-01
IU → mcgmcg → IU
Result
0 mcg
Conversion factor: 1 IU = 0.025 mcg
Source: NIH Office of Dietary Supplements, WHO 2026
Common Dosages
| IU | mcg |
|---|---|
| 400 IU | 10 mcg |
| 1,000 IU | 25 mcg |
| 2,000 IU | 50 mcg |
| 5,000 IU | 125 mcg |
| 10,000 IU | 250 mcg |
Click any row to use that value in the calculator
Frequently Asked Questions
1000 IU of Vitamin D3 equals 25 mcg. The conversion factor is 1 IU = 0.025 mcg, based on WHO/NIH 2026 standards.
The tolerable upper intake level (UL) for Vitamin D3 is 100 mcg (4000 IU) per day for adults, as established by the NIH Office of Dietary Supplements. Exceeding this limit may cause adverse effects.
International Units (IU) are the traditional measurement for fat-soluble vitamins. While mcg is the metric standard, IU accounts for biological activity. Many supplement labels now show both units for clarity.