Converting Vitamin D mcg to IU | Chart and Calculator
Written By Kobi Nathan, Pharm.D., M.Ed., CDP, BCGP, AGSF
Sleep Disorders
July 28, 2023

Important note: The information below does not constitute medical advice and is purely informational. No internet post or YouTube post should claim to offer medical advice. Always check with your doctor to ensure your Vitamin D intake is appropriate. Inappropriate use can be dangerous.

Vitamin D mcg to IU conversion

There are 40 IU per mcg of Vitamin D.

Using this equation, we can easily convert any corresponding value of Vitamin D.

For example, there are 2,000 IU in 50 mcg of Vitamin D (40 x 50 = 2,000).

And there are 5,000 IU in 125 mcg of Vitamin D (40 x 125 = 5,000).

The above equivalents are the most common regimens seen in people.

The table below shows other common doses:

Vitamin D IU to mcg and mg conversion chart

Dose in International Units (IU)Dose in micrograms (mcg)Dose in milligrams (mg)

Vitamin D conversion calculator

If you want to do a quick conversion, use the tool below to convert Vitamin D both ways between IU and mcg.

Just use the drop-down carrot to scroll down to “Vitamin D,” specify the unit you want (mcg or mg), then type in the strength accordingly.

The exact conversion will be calculated for you.

You can use this calculator to calculate the conversions for many other drugs, as you can see:

mcg to IU Converter

How to convert mcg to mg


Here’s a short video on how to convert mcg to mg using simple math:

Now, let’s dive deeper into Vitamin D, dosing, food sources of vitamin D, and common issues regarding its use…

It is always recommended to consult a healthcare professional for personalized advice on Vitamin D intake.

Key Takeaways

  • IU is a measure of biological activity used to define a substance’s effect, not its weight.
  • International units vary for different substances (Vitamin A vs. Vitamin D vs. Vitamin E, etc.)
  • As of 2021, drug manufacturers started listing IU and mg/mcg on drug labels.

Overview of Vitamin D

Vitamin D, or “calciferol,” is a fat-soluble nutrient.

This means it can be naturally found in certain foods, added to others, and available as a supplement.

Additionally, your body produces vitamin D when exposed to sunlight, specifically the ultraviolet (UV) rays.

Interestingly, the vitamin D you get from sunlight, food, and supplements is initially inactive and needs to go through a two-step process in your body to become active.

This process is called hydroxylation.

The first step occurs in the liver, where vitamin D is converted to a compound called 25-hydroxyvitamin D, or “calcidiol.”

The second step primarily happens in the kidney, transforming the compound into the active form of vitamin D, known as 1,25-dihydroxyvitamin D or “calcitriol.”

Vitamin D plays a critical role in the body.

It helps absorb calcium in our digestive system and maintains a healthy balance of calcium and phosphate in our bloodstream.

This balance is important for normal bone formation and preventing hypocalcemic tetany, a condition causing muscle cramps and spasms due to low calcium levels.

Vitamin D also contributes to bone growth and the renewal process of specialized cells known as osteoblasts and osteoclasts.

If a person doesn’t get enough vitamin D, their bones may become thin, brittle, or misshapen.

It’s crucial to have enough vitamin D to prevent diseases related to bone weakening.

In children, vitamin D helps prevent rickets, which causes soft, weak bones.

In adults, it prevents osteomalacia, leading to soft bones and muscular weakness.

Moreover, together with calcium, vitamin D aids in protecting older adults from developing osteoporosis, a condition characterized by fragile bones.

Low vitamin D and IBS symptoms are also connected. Read my detailed article exploring this issue here.

Research suggests that taking Vitamin D and Vitamin K2 together may yield positive health benefits. Click here to read my article about this interesting concept.

Vitamin D2 vs Vitamin D3

There are two main forms of Vitamin D:

  • Vitamin D2 (ergocalciferol).
  • Vitamin D3 (cholecalciferol).

Vitamin D3 is exclusively obtained from foods derived from animals, while D2 primarily originates from plant-based foods and those enriched with nutrients (cereals, etc.).

Vitamin D Content in Foods

The vitamin D content in foods varies significantly, presenting a range of dietary sources to meet the recommended intake.

Fatty fish, such as salmon and mackerel, are good sources of vitamin D, with amounts reaching up to 25 mcg per serving.

Cod liver oil, although not a common food item, contains a high concentration of vitamin D.

Certain mushrooms, particularly those exposed to ultraviolet light, also contribute to vitamin D intake.

Fortified foods, including milk and breakfast cereals, often have vitamin D added, enhancing their nutritional value and making it easier to meet the body’s requirement for this essential vitamin.

The table below details specific amounts of Vitamin D in some of the most common foods:

Vitamin D in Selected Foods

Foodmcg per servingIU per servingPercent Daily Value (DV)
Cod liver oil, 1 tablespoon34.01,360170
Trout (ranibow), farmed, cooked, 3 ounces16.264581
Salmon (sockeye), cooked, 3 ounces14.257071
Mushrooms, white, raw, sliced, exposed to UV light, one-half cup9.236646
Milk, 2%, vitamin D fortified, 8 fluid ounces2.912015
Soy, almond, and oat milks, Vitamin D fortified, 8 fluid ounces2.5-3.6100-14413-18
Cereal, fortified with 10% of DV for Vitamin D, 1 serving2.08010
Sardines (Atlantic), canned in oil, drained, 2 sardines 1.2466
Egg, 1 large, scrambled1.1446
Liver, beef, braised, 3 ounces1.0425
Tuna fish (light), canned in water, drained, 3 ounces1.0405
Cheese, cheddar, 1.5 ounce0.4172
Portabella mushrooms, raw, one-half cup0.141
Chicken breast, roasted, 3 ounces0.141
Beef, ground, 90% lean, broiled, 3 ounces01.70
Broccoli, raw, chopped, one-half cup000
Banana, large, 000
Source: Accessed 7/27/2023.

Risks of excessive Vitamin D

Excessive intake of this essential nutrient, often through over-supplementation, can lead to toxicity and adverse health effects, illustrating the importance of adhering to recommended daily allowances.

High intakes of vitamin D can cause a range of problems:

  • Hypercalcemia: This condition, characterized by elevated calcium levels in the blood, can result from excessive vitamin D intake. Symptoms may include nausea, vomiting, and in severe cases, kidney damage.
  • Altered immune function: High vitamin D levels can disrupt the immune system, potentially leading to autoimmune diseases or an increased risk of infection.
  • Other risks: Over-supplementation can lead to other health hazards, including heart disease and certain types of cancer. Regular monitoring of vitamin D levels is essential to decrease the risks of excessive vitamin D.

This is why I suggest your doctor oversee your Vitamin D supplementation.

The video below from a doctor describes what can happen when you take too much Vitamin D:

The shift from IU to mcg

On August 15, 2019, the U.S. Food and Drug Administration (FDA) released a step-by-step guidance for industry requiring all nutrition facts and supplement labels to convert previous units of measure from IU to mcg.

Specifically, Vitamin A, D, and E labels must list the strength of their ingredients in metric units, such as milligrams or micrograms.

To go to the specific document citing 21 CFR Part 101, click here.

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