How this calculator works
Vitamin A activity depends on chemical form and whether carotenoids come from food or supplements. IU conversions therefore require a source choice. This page converts a single known source; mixtures must be converted component by component and then summed as RAE. The comparison is against the DRI intake target, not a recommended supplement dose. Preformed vitamin A has a distinct upper limit and excess is especially concerning during pregnancy. The result is an estimate for information only and is not medical advice.
Formula
1 IU = 0.3 mcg RAE for retinol or supplemental beta-carotene; 0.05 for food beta-carotene; 0.025 for food alpha-carotene or beta-cryptoxanthin. 1 mcg RAE = 1 mcg retinol = 2 mcg supplemental beta-carotene = 12 mcg food beta-carotene = 24 mcg other listed food carotenoids.
Worked example
3000 IU retinol equals 900 mcg RAE. By contrast, 3000 IU food beta-carotene equals 150 mcg RAE. A source mass of 10800 mcg food beta-carotene equals 900 mcg RAE.
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Frequently asked questions
Can I use the same conversion for all foods?
No. The source matters, and mixed sources require their component proportions.
Is RAE the same as older retinol equivalents?
Not for all carotenoids. Modern RAE uses different food-carotenoid activity factors.
Is reaching 100% a supplement recommendation?
No. The reference includes dietary intake, and upper limits and clinical context matter.