How to Read Supplement Labels

The parts of a Supplement Facts panel

Read the panel from the top down:

1. Supplement Facts. The heading at the top of the box.
2. Serving Size. The amount the panel describes, written in a word that fits the product, like "1 tablet" or "2 capsules".
3. Servings Per Container. How many servings are in the pack. The rule lets a maker skip this line if the net contents already say it.
4. Amount Per Serving. The heading over the list of ingredients and their amounts by weight.
5. % Daily Value. A column that compares each amount to the FDA's Daily Value for that nutrient.
6. The star note. A star in the % Daily Value column points to the words "Daily Value not established" at the bottom.

Every number in the panel is for one serving, not for the whole pack. That is the first thing to check.

The units on the panel

The amounts on the panel use weight units, plus a few special ones. Here is what each means:

The FDA set these units for US labels and explained how to convert old IU values in a 2019 guide. If you need to switch units, use the mg to mcg converter or the mcg to IU converter. If mcg is new to you, start with what is mcg.

A sample panel, read line by line

These lines use the FDA's own worked examples from its 2019 guide. They are not a real product and not amounts to take.

How to read it:

• Vitamin A, 1,050 mcg. The unit for vitamin A is mcg RAE. The FDA's example turned 3,500 IU of beta carotene into 1,050 mcg RAE with a factor of 0.3.
• Vitamin D, 25 mcg (1,000 IU). The mcg number comes first, as the rule requires. The IU number in brackets is optional.
• Folate, 680 mcg DFE. The brackets show the folic acid by weight. DFE adjusts for the form, so folic acid counts 1.7 times. 400 mcg × 1.7 = 680 mcg DFE.

Proprietary blends

Some panels list a "Proprietary Blend", or a blend with a made up name. The rule says the panel must give the total weight of the blend. The other ingredients inside are listed from most to least by weight, and their separate amounts do not have to be shown. Vitamins and minerals that have a Daily Value still show their own amounts.

So for those other ingredients, a blend line tells you the total and the order, but not how much of each one is in it.

Tips that save mistakes

• Check the unit on every line. 500 mcg and 500 mg are 1,000 times apart. The mg vs mcg guide shows why.
• Read mcg as written. The FDA uses mcg on labels, and a safety group, ISMP, asks people not to use µg because it can be misread as mg.
• Note that the rule lets zeros after a point be dropped. So you may see 2 mg and not 2.0 mg.