Vitamin A Calculator — IU to mcg RAE Converter
Convert vitamin A from IU to mcg RAE, add beta-carotene from food and supplements, and see how your total stacks up against the RDA and the 3,000 mcg RAE upper safety limit.
Sex
IU
mcg
mcg
Retinol activity equivalents — the standard unit for comparing all vitamin A sources
- 1
Retinol → mcg RAE
5,000 × 0.3 = 1,5001 IU preformed retinol = 0.3 mcg RAE (IOM 2001) - 2
Supplement beta-carotene → mcg RAE
0 ÷ 2 = 0 - 3
Food beta-carotene → mcg RAE
0 ÷ 12 = 0 - 4
Total vitamin A
1,500 + 0 + 0 = 1,500
How does this calculator work?
Convert vitamin A from IU to mcg RAE using 1 IU retinol = 0.3 mcg RAE. Add beta-carotene (2 mcg supp = 1 mcg RAE; 12 mcg food = 1 mcg RAE) for total intake. RDA is 900 mcg RAE (men) or 700 mcg RAE (women); the adult UL for preformed retinol is 3,000 mcg RAE — beta-carotene from food does not count toward the UL.
Formula
How this is calculated
Vitamin A is found in food and supplements in several chemical forms. Preformed vitamin A (retinol) from animal sources and supplements is measured in IU or micrograms. Provitamin A carotenoids such as beta-carotene from plant foods are also vitamin A precursors but convert much less efficiently. The standard unit for comparing all sources is the Retinol Activity Equivalent (mcg RAE), defined by the Institute of Medicine (IOM) in 2001.
Conversion factors: 1 IU of retinol = 0.3 mcg RAE (equivalently, 1 mcg RAE = 3.33 IU). Supplemental beta-carotene is absorbed more efficiently than food beta-carotene: 2 mcg of supplement beta-carotene = 1 mcg RAE, whereas 12 mcg of food beta-carotene = 1 mcg RAE. This calculator adds all three sources in mcg RAE so you can see your total intake.
Only preformed vitamin A (retinol) counts toward the Tolerable Upper Intake Level (UL) of 3,000 mcg RAE per day for adults, because dietary beta-carotene does not cause vitamin A toxicity — the body down-regulates its conversion. Chronic excess preformed vitamin A can cause liver damage, bone loss, and is teratogenic in pregnancy. Always check supplement labels: many multivitamins contain both retinol and beta-carotene.
Frequently asked questions
Multiply IU by 0.3 to get mcg RAE (for preformed retinol). For example, 5,000 IU of retinol = 1,500 mcg RAE. Beta-carotene conversions are different: 1 IU supplemental beta-carotene = 0.15 mcg RAE, and food beta-carotene converts at about 0.05 mcg RAE per IU.
Dietary beta-carotene has no established UL because the body limits its conversion to vitamin A. However, high-dose beta-carotene supplements (≥ 20 mg/day) have been associated with increased lung cancer risk in smokers and should be avoided by that group.
Many multivitamins supply 750–900 mcg RAE, often as a mix of retinol and beta-carotene. Check the label for the form — labels now typically list "vitamin A (as retinyl acetate and beta-carotene)" with the mcg RAE or IU amount.
Also known as
TG we-Calculate Editorial Team. (2026). Vitamin A Calculator — IU to mcg RAE Converter [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/vitamin-a-calculator
TG we-Calculate Editorial Team. "Vitamin A Calculator — IU to mcg RAE Converter." TG we-Calculate. 2026. https://we-calculate.com/calculator/vitamin-a-calculator.
TG we-Calculate Editorial Team, "Vitamin A Calculator — IU to mcg RAE Converter," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/vitamin-a-calculator
@misc{wecalculate_vitamin_a_calculator, title = {Vitamin A Calculator — IU to mcg RAE Converter}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/vitamin-a-calculator}}, year = {2026}, note = {TG we-Calculate} }
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