The formula
%NRV = amount per daily dose ÷ NRV × 100
Example: a capsule with 25 µg of vitamin D. The NRV for vitamin D is 5 µg, so 25 ÷ 5 × 100 = 500%.
Always use the amount per daily dose, not per capsule, if the dose is more than one capsule. For a dose of 2 tablets each with 100 mg of magnesium, use 200 mg: 200 ÷ 375 × 100 = 53%.
UK NRV values
These are the reference values for adults set out in the food information rules (Annex XIII).
| Nutrient | NRV | Unit |
|---|---|---|
| Vitamin A | 800 | µg |
| Vitamin D | 5 | µg |
| Vitamin E | 12 | mg |
| Vitamin K | 75 | µg |
| Vitamin C | 80 | mg |
| Thiamin (B1) | 1.1 | mg |
| Riboflavin (B2) | 1.4 | mg |
| Niacin (B3) | 16 | mg |
| Vitamin B6 | 1.4 | mg |
| Folic acid | 200 | µg |
| Vitamin B12 | 2.5 | µg |
| Biotin | 50 | µg |
| Pantothenic acid | 6 | mg |
| Potassium | 2000 | mg |
| Chloride | 800 | mg |
| Calcium | 800 | mg |
| Phosphorus | 700 | mg |
| Magnesium | 375 | mg |
| Iron | 14 | mg |
| Zinc | 10 | mg |
| Copper | 1 | mg |
| Manganese | 2 | mg |
| Fluoride | 3.5 | mg |
| Selenium | 55 | µg |
| Chromium | 40 | µg |
| Molybdenum | 50 | µg |
| Iodine | 150 | µg |
Common mistakes
- Mixing units. Entering selenium in mg instead of µg gives an answer 1,000 times too high.
- Using the wrong form. The NRV applies to the vitamin or mineral itself, not the compound. 100 mg of magnesium citrate does not contain 100 mg of magnesium.
- Giving %NRV for non-vitamins. Ingredients like CoQ10, omega-3 or ashwagandha have no NRV. Show their amount and mark the %NRV column with a dash or “†no NRV established”.
- Forgetting the footnote. Explain “NRV” on the label, for example “*NRV = Nutrient Reference Value”.
Not legal advice. This guide covers the general rules for food supplements sold in Great Britain. Check your own product with a regulatory adviser, your local Trading Standards team or your Primary Authority partner.