This vitamin A calculator converts different forms of vitamin A to Retinol Activity Equivalents expressed in the mass unit micrograms, which are used in Dietary Reference Intakes for vitamin A. This is also a new requirement for nutrition labels of supplements, where vitamin A was listed in international units (IUs) before.

Read the article below to find out more about vitamin A function, its sources, the consequences of vitamin A deficiency, and vitamin A toxicity. We will also answer the question of how much vitamin A per day you should eat and explain how beta carotene to vitamin A conversion works.

Disclaimer: We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace the professional advice of a health care provider.

What is vitamin A?

Vitamin A is a fat-soluble vitamin that is essential for humans. Just like other vitamins, it needs to be provided with food (or supplements when required) in recommended amounts, as its deficiency is associated with serious health problems.
There are two forms of vitamin A available in food:

  • Preformed vitamin A (retinol and its esterified form, retinyl ester); and
  • Provitamin A carotenoids (β-carotene, α-carotene, β-cryptoxanthin).

What does vitamin A do? Vitamin A function

Have you ever wondered what does vitamin A do? Well, it turns out that this vitamin has multiple functions in the human body:

  • It is necessary for normal human growth and development;
  • It supports the functioning of our immune system;
  • It is required for good vision - both low-light and color;
  • It plays an important role in gene transcription; and
  • It helps maintain healthy skin.

Vitamin A deficiency symptoms

As vitamin A has many functions in the human body, its deficiency is associated with serious health problems. One of the earliest and the most specific manifestations of vitamin A deficiency is impaired vision, particularly in dim light, also known as night blindness. If the deficiency persists, further eye damage may occur, which can eventually result in total blindness. Other consequences of vitamin A deficiency include impaired immunity and various skin problems. Moreover, the right amounts of vitamin A are extremely important for pregnant and breastfeeding women to support normal child development.

Vitamin A deficiency is rather rare in developed countries, however, it is common in many developing countries. Some supplementation strategies have been introduced there, including the . The World Health Organization estimated that vitamin A supplementation has saved 1.25 million lives in 40 countries since 1998.

What should I eat? - vitamin A foods

Different forms of vitamin A can be found in many foods:

  • Preformed vitamin A: liver, fish oils, milk, eggs, butter, cheese; and
  • Provitamin A: leafy green vegetables, orange and yellow vegetables (e.g. pumpkin, squash, carrots), tomatoes and their products, various fruits (e.g. mango, cantaloupe, dried apricots), some vegetable oils.

How much vitamin A per day?

The Dietary Reference Intakes (DRIs) for vitamin A developed by the Food and Nutrition Board at the Institute of Medicine of the National Academies are expressed as Recommended Dietary Allowance (RDA). It means that this amount is sufficient to meet the nutrient requirements of nearly all (97% – 98%) healthy individuals. The recommendations depend on age and sex, and you can see them below:

  • Infants 0-6 months: 400 μg/day (adequate intake, not RDA);
  • Infants 6-12 months: 500 μg/day (adequate intake, not RDA);
  • Children 1-3 years: 300 μg/day;
  • Children 4-8 years: 400 μg/day;
  • Children 9-13 years: 600 μg/day;
  • Males > 14 years: 900 μg/day;
  • Females > 14 years: 700 μg/day;
  • Pregnancy: 770 μg/day (750μg/day for women 14-18 years old); and
  • Breastfeeding: 1300 μg/day (1200 μg/day for women 14-18 years old).

Too much vitamin A? Vitamin A toxicity

Vitamin A is fat-soluble, which means it can accumulate in our body. Large amounts of beta-carotene and other provitamin A carotenoids are not associated with major adverse effects, but preformed vitamin A can have significant toxicity, so it is possible to have too much vitamin A. The symptoms of hypervitaminosis may include nausea, irritability, anorexia (reduced appetite), vomiting, blurry vision, headaches, and hair loss, but it can also result in liver damage.

The vitamin A calculator

Have you ever wondered how beta carotene to vitamin A conversion works? Our vitamin A calculator will do it for you. 🙃

Vitamin A has previously been reported in international units (IU), but new labelling guidelines require the use of a new unit - RAE (retinol activity equivalent). This allows takes into account the differing bioavailability of the forms. So how do we do it? The rules are as follows:

  • 1 IU retinol = 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

The above correlations have been implemented into our vitamin A calculator. You can use it both ways - no matter if you want to exchange IU to RAE, or the other way round.

Interested in nutritional calculators? You may also check our vitamin D, micronutrient, macronutrient, protein, fat intake, carbohydrate, and fiber calculators.


Joanna Michałowska, PhD candidate
Recommended Daily Allowance
Retinol (animal source) 🧈
International Units
Retinol Activity Equivalents
Dietary beta-carotene from food (plant source) 🥕
International Units
Retinol Activity Equivalents
Supplemental beta-carotene 💊
International Units
Retinol Activity Equivalents
Dietary alpha-carotene and/or beta-cryptoxanthin (plant source) 🍊
International Units
Retinol Activity Equivalents
Total Retinol Activity Equivalents (RAEs)
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