How to calculate % Daily Value for supplements

Percent Daily Value (%DV) tells you how much of a reference amount one serving provides. On a Supplement Facts panel it is calculated from the amount per serving and the Daily Value in 21 CFR 101.9.

The formula

%DV = amount per serving ÷ Daily Value × 100

Step 1: get the amount per serving

If you know the amount per capsule, multiply it by the capsules per serving. For example, 7.5 mg of zinc per capsule × 2 capsules = 15 mg per serving.

Step 2: use the same unit as the Daily Value

Several Daily Values use special units:

• Vitamin A in mcg RAE. Retinol at 1 IU = 0.3 mcg RAE.
• Folate in mcg DFE. 1 mcg of folic acid = 1.7 mcg DFE.
• Niacin in mg NE.
• Vitamin D in mcg. 1 IU = 0.025 mcg.
• Vitamin E in mg. Natural form: 1 IU = 0.67 mg. Synthetic form: 1 IU = 0.45 mg.

The factors come from FDA’s 2019 unit-conversion guidance. The unit converter applies them.

Step 3: divide, multiply and round

Zinc 15 mg ÷ 11 mg × 100 = 136.36%, which is declared as 136%. Supplement Facts %DVs are declared to the nearest whole percent (21 CFR 101.36(b)(2)(iii)).

The “less than 1%” rule

For nutrients with a Daily Reference Value, such as total carbohydrate, protein, fat and fiber, an amount that is present but rounds to 0% is declared as “Less than 1%” or “<1%”. For example, 1 g of carbohydrate ÷ 275 g = 0.36%, declared as <1%.

Common mistakes

• Using the weight of the compound instead of the nutrient. 100 mg of magnesium citrate is not 100 mg of magnesium.
• Mixing units, for example using mcg of folic acid against a DFE Daily Value.
• Using outdated Daily Values. Our ruleset uses the values in 21 CFR 101.9(c)(8)(iv) and (c)(9) as published on eCFR, with the review date shown.

Try it with the Daily Value calculator.