What does 1000 IU convert to in mg?

Overview
Definition of milligram
Definition of international unit (IU)
Difference between Milligram and International unit
How to Convert Between IU & mg?
Drugs that measured by mg and others by IU
What does an IU measure used for?

1- Overview:

All drugs must have a specific concentration to identify and control the biological effect, most of these drugs have a concentration unit of milligram (mg) or gram (g), but there are a different class of medications as biological drugs and some of vitamins its concentration is measured by international unit.
In this article we will show you the difference between the two units.

2- Definition of milligram (mg):

Milligram: A unit of measurement of mass in the metric system equal to a thousandth of a gram. A gram is equal to the mass of one milliliter, one thousandth of a liter, of water at 4 degrees C.

The abbreviation for milligram is mg.1

3-Definition of international unit:

International Unit (IU), in pharmacology, quantity of a substance, such as a vitamin, hormone, or toxin, that produces a specified effect when tested according to an internationally accepted biological procedure. For certain substances, the IU has been identified with a weight of a particular purified form of the material; for example, one gram of vitamin A acetate contains 2.904 × 106 IU.2

International unit is different from substance to substance, there are international agreement for each substance. For example, 1 IU of Vit A does not equal 1 IU of Vit C.

4- Difference between Milligram and International unit

Milligram used to measure the mass and concentration of the substance and follow the metric system.

But the international unit measures the biological effect of Vitamins or toxins.3

IU (international unit): An international unit (IU) is an internationally accepted amount of a substance.

This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines).

The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol. Nonetheless, most IUs are quite handy and helpful in use as a means of standardizing measures.

All international units are officially defined by the International Conference for Unification of Formulae.

For example:

VITAMIN A : One milligram of beta carotene = 1667IU of Vitamin A activity.

15mg of beta carotene = 25,000IU of Vitamin A activity.

VITAMIN E : One milligram of Vitamin E = 1.21 to 1.49IU (depending on the carrier).

400IU of d-alpha tocopherol = 268mg.

VITAMIN D: One microgram of Vitamin D = 40 IU.

400IU of Vitamin D = 10ug.

And if their biological equivalent of the same substance may have different IU

For example:

Vitamin A: There are two widely available preparations of vitamin A: retinol and beta carotene. The IU equivalent of vitamin A in the retinol format is 0.3 µg per 1 IU. The value for beta carotene is 0.6 µg per IU. If the RDA for vitamin A as a retinol preparation is 3,000 IU, the equivalent in micrograms is 900 µg. Converted to milligrams, this amount equals 0.9 mg.

Vitamin E: Vitamin E is available in two formats: d-alpha-tocopherol, a natural source, and dl-alpha-tocopherol, a synthetic source. One IU of d-alpha-tocopherol equals 0.67 mg. Converted to micrograms; it equals 670 µg. The dl-alpha-tocopherol formulation contains 0.9 mg vitamin E per IU. In micrograms that is equivalent to 900 µg. The RDA for an adult is 22.4 IU of the natural version and 33.3 IU of the synthetic version, or about 15 mg and 30 mg.

Vitamin D: The most commonly available vitamin D preparation is vitamin D3, or cholecalciferol. 40 IU of vitamin D equals 1 µg, which can be converted to 0.001 mg. The RDA for an adult range from 600-800 IU. In micrograms, that would be 15 to 20 µg. Using milligrams changes the value range to 0.015-0.020 mg.5

5- How to Convert Between IU & mg?

Each IU Vitamin has its specific mass of millimeter which differ from vitamin to another, and to convert from IU to Mg you must know the converting value.

Vitamin A: 1 IU is the biological equivalent of 0.3 mcg retinol, or of 0.6 mcg beta-carotene
Vitamin C: 1 IU is 50 mcg L-ascorbic acid
Vitamin D: 1 IU is the biological equivalent of 0.025 mcg cholecalciferol or ergocalciferol
Vitamin E: 1 IU is the biological equivalent of about 0.67 mg d-alpha-tocopherol, or 0.9 mg of dl-alpha-tocopherol.4

Example conversion

Let’s say that I have a soft gel capsule that contains 500 IU of Vitamin A as retinol. To convert this to mcg, using the information above, I would multiply it by 0.3:

500 × 0.3 = 150mcg.

Conversely, if the soft gel capsule was described as ‘150mcg of Vitamin A as retinol’ and I wanted to convert to IU, I would divide it by 0.3.

150 ÷ 0.3 = 500 IU.

6- Drugs that measured by mg and others by IU

Most of drugs measured by Mg and gm even with different dosage forms as tablets or suspension or syrup using mg/ml.
For example : antibiotics as Amoxicillin – Flucloxacillin – ceftriaxone – cefotaxime and all Cephalosporins – metronidazole
Most of OTC drugs measured by using mg : as Paracetamol – aspirin – Pantoprazole – omeprazole
There are many of drugs measured using IU

For example: Insulin and other hormone as oxytocin

Penicillin as Benzathine penicillin G measured by IU.

many of blood drugs as coagulation factor VIII and erythropoietin and Heparin

7- What does an IU measure used for?

IU used in measurement of vitamins as vitamin A and vitamin B and Vitamin D and Vitamin E and their bioequivalent substances, also enzymes of human body in biological Assay, and hormone as oxytocin and insulin and vaccines

8- What Does IU Stand for in Vitamins?

So what does IU mean on vitamin labels?
When it comes to vitamins and minerals, IU stands for the exact same thing: international unit.
The IU of a vitamin tells you how much that vitamin is going to make a difference in your body.
IU measures how specific forms of vitamins are going to react in your body differently.
For example, vitamin D exists as cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2).
Vitamin D3 (cholecalciferol) is going to have a different effect on the body than ergocalciferol will have.
Likewise, vitamin A is available as retinol or beta-carotene, while vitamin E comes as alpha-tocopherol or dl-alpha-tocopherol. Each one of these fat-soluble vitamins has a different level of potency or biological activity in the body. Therefore, we have to measure vitamin levels with the standard unit of measurement, the IU.

What Does 5,000 IU Stand For?

5,000 IU does not tell you the amount based on mass.
In fact, the IU does not measure mass or volume.
Remember, each vitamin supplement has its own level of biological effectiveness. The IU measures the effectiveness rather than the weight or amount.
Let’s think about an example. 5,000 mg of vitamin D3 is going to have a different effect on the body than 5,000 mg of beta-carotene.
These measurements don’t mean anything in terms of effectiveness, so we need to measure the effectiveness of each vitamin through a standardized measurement like the IU.
5,000 IU of Vitamin D3 is a standard daily amount of vitamin D3, especially for women who have a slightly low vitamin D level.
On the other hand, 5,000 IUs of beta-carotene is too much of the vitamin.
In fact, this much vitamin A can leave someone prone to fractures.

Is IU the Same as MG or MCG?

IU is not the same as mg or mcg. To refresh, IU stands for international unit, mg stands for milligrams, and mcg stands for micrograms.
Each one of these units of measurement stands on its own. The difference between all of these units is crucial to understand.
IU doesn’t measure mass or volume, while mg and mcg measure mass. While both of these measure weight, mg is 1,000 times more than mcg.
When you’re reading the vitamin label, you need to read carefully to ensure that you’re getting the dosage that you need.
Unfortunately, some vitamin labels use IUs while others use mg and mcg. You may find yourself in the pharmacy aisle needing to do a little math.
Or, you can cross your fingers in hope that the back of the bottle tells you the weight and IU values.
If you’re converting from IU to weight, you need to divide by the conversion factor.
However, if you’re converting from weight to IU, you need to multiply by the conversion factor.
Since each vitamin has its own level of potency and biological effectiveness, each kind of vitamin has its own conversion factor.

Is 1,000 IU the Same as 1,000 MG?