Ask The Pharmacist: Vitamin D3 Dosing Question

In our latest question and answer, the pharmacist discusses converting units of Vitamin D3 to micrograms.


How many MCG is 5000 IU Vitamin D3?

Asked by Florinda On Jul 16, 2023

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jul 17, 2023
Last updated Dec 08, 2023

Key points

  • 1 microgram (mcg) of vitamin D is equal to 40 International Units (IU).

Quick Answer

5000 IU of vitamin D3 is equivalent to 125 micrograms (mcg).

Detailed Answer

Vitamin D3 is often measured in International Units (IU), but many vitamin D3 products also provide the microgram (mcg) amount for reference.

To convert between IU and mcg (micrograms) for vitamin D3, a conversion factor is used: 1 mcg of vitamin D is equal to 40 IU. This conversion factor helps determine the appropriate dosage of vitamin D3 supplements.

Using the conversion factor of 1 mcg = 40 IU, we can calculate the mcg equivalent of 5000 IU of vitamin D3:

5000 IU รท 40 = 125 mcg (micrograms)

Therefore, 5000 IU of vitamin D3 is equal to 125 mcg.

Here are a few more examples to illustrate the conversion:

  • 1000 IU of vitamin D3 = 25 mcg
  • 2000 IU of vitamin D3 = 50 mcg
  • 4000 IU of vitamin D3 = 100 mcg
  • 10,000 IU of vitamin D3 = 250 mcg

I want to point out here as well the difference between micrograms and milligrams.

A microgram is equal to one millionth of a gram or 0.001 milligrams. On the other hand, a milligram is equal to one thousandth of a gram or 1000 micrograms.

To convert micrograms to milligrams, you need to divide the number of micrograms by 1000. For example, if you have 500 micrograms (500 mcg), dividing it by 1000 gives you 0.5 milligrams (0.5 mg). Conversely, to convert milligrams to micrograms, you need to multiply the number of milligrams by 1000.

In your specific question about 5,000 IU of Vitamin D3 equaling 125 mcg, that is equal to 0.125 milligrams (mg).

Final Words

Thank you for reaching out to us! Feel free to contact us again if you have any further questions.

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

Recent Questions