From: Vitamin E, Fact Sheet for Health Professionals, National Institutes of Health

Vitamin E is listed on the Nutrition Facts and Supplement Facts labels in milligrams. The FDA required manufacturers to use milligrams on labels starting in January 2020.

To convert from mg to IU:
1 mg of alpha-tocopherol is equivalent to 1.49 IU of the natural form or 2.22 IU of the synthetic form.

To convert from IU to mg:
1 IU of the natural form is equivalent to 0.67 mg of alpha-tocopherol.
1 IU of the synthetic form is equivalent to 0.45 mg of alpha-tocopherol.

For example:
15 mg of natural alpha-tocopherol = 22.4 IU (15 mg x 1.49 IU/mg = 22.4 IU).
200 IU of natural alpha-tocopherol = 134 mg (200 IU x 0.67 mg/IU = 134 mg).