Vitamin A Calculator (IU to mcg RAE, RDA and upper limit)

Understanding the vitamin A calculator — concept and principle

This calculator converts a vitamin A amount on a supplement or food label from international units (IU) or micrograms into micrograms of retinol activity equivalents (mcg RAE), and compares it with the recommended intake and the upper limit for your life stage. Labels have changed units over the years, so this conversion is a common source of confusion.

IU → mcg RAE: with the default inputs the result is 1,500 mcg RAE (167% of RDA · 50% of UL).

How it is calculated

mcg RAE = amount × factor for the form:

1 IU retinol (retinyl acetate or palmitate) = 0.3 mcg RAE
1 IU supplemental beta-carotene = 0.3 mcg RAE; 1 IU dietary beta-carotene = 0.05 mcg RAE
1 IU dietary alpha-carotene or beta-cryptoxanthin = 0.025 mcg RAE
1 mcg retinol = 1 mcg RAE; 1 mcg supplemental beta-carotene = 0.5; 1 mcg dietary beta-carotene = 1/12; 1 mcg alpha-carotene or beta-cryptoxanthin = 1/24

Share of RDA = RAE ÷ RDA × 100; share of upper limit = RAE ÷ UL × 100 (preformed vitamin A only).

The principle

Vitamin A comes as preformed retinol from animal foods and supplements, and as carotenoids from plants that the body converts to retinol. Conversion and absorption differ a lot between forms, so RAE puts them on a common scale of biological activity. Too much preformed vitamin A can be toxic, so the upper limit applies to retinol and its esters, not to beta-carotene, which the body converts only as needed.

Worked example

Default inputs: 5,000 IU of retinol, man 19 years or older.

RAE = 5,000 × 0.3 = 1,500 mcg RAE.
RDA for men = 900 mcg RAE → 1,500 ÷ 900 = 167%.
Upper limit = 3,000 mcg → 1,500 ÷ 3,000 = 50%; upper limit applies Yes: preformed vitamin A.

Each point is the calculator re-run with only “Amount of vitamin A” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Amount of vitamin A	Vitamin A (mcg RAE)
1,250	375
2,500	750
3,750	1,125
5,000	1,500
6,250	1,875
7,500	2,250
10,000	3,000

How to read the result

Where does your result fall?

Above 100% of the RDA from one product is not harmful by itself as long as total preformed vitamin A from all sources stays under the upper limit. Regular intake above the limit can damage the liver and bones, and in pregnancy high preformed vitamin A can harm the baby. Count multivitamins, fish liver oils and fortified foods together.

Common mistakes

Treating all IU as equal; beta-carotene IU from food count far less.
Forgetting cod liver oil and liver, which are very rich in retinol.
Applying the upper limit to beta-carotene.

Keep in mind: This is general nutrition information, not medical advice. Pregnant people should not take high-dose vitamin A supplements without medical advice.

Frequently asked questions

How many mcg is 5,000 IU of vitamin A?

1,500 mcg RAE if it is retinol; less if it is dietary beta-carotene.

What is the adult upper limit?

3,000 mcg of preformed vitamin A a day.

Can I get too much vitamin A from carrots?

No. Beta-carotene from food is not toxic, though very large amounts can tint the skin orange.

Sources: NIH Office of Dietary Supplements, "Vitamin A and Carotenoids: Fact Sheet for Health Professionals" · Institute of Medicine, Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc, National Academies Press, 2001

Checked 9 Nov 2026. NIH Office of Dietary Supplements, “Vitamin A and Carotenoids — Fact Sheet for Health Professionals” (updated 15 June 2022): IU conversions, RAE equivalents, Table 1 (RDAs/AIs) and Table 3 (ULs for preformed vitamin A), based on the Institute of Medicine DRI report (2001).

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