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Supplement Stack Calculator – Add Up Vitamins and Minerals

This supplement stack calculator adds up every product you take and compares each nutrient with US and EU reference intakes and upper limits.

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Write “Product: nutrient amount, …” or just “nutrient amount”, e.g. “Zinc 15 mg”. Units: mg, µg (mcg), g and IU.

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For information only, not medical advice. Reference values describe healthy population groups and do not tell you what dose you should take. Ask a doctor, pharmacist or dietitian before starting, stopping or combining supplements, especially if you are pregnant, take medication or have a health condition.

Reference values are for adults aged 19 and over. Children have different, lower limits. Sources: US Dietary Reference Intakes (NIH Office of Dietary Supplements) and EFSA Dietary Reference Values and Tolerable Upper Intake Levels (2024). Reviewed October 7, 2026.

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How to use the Supplement Stack Calculator

  1. 1 Enter each product on its own line, for example “Multivitamin: vitamin D 10 µg, zinc 10 mg”.
  2. 2 Use the amount you take per day and the unit on the label: mg, µg (mcg), g or IU.
  3. 3 Choose your age and sex to see the matching reference values and check nutrients that appear in more than one product.

Why add up your supplements?

Many people take a multivitamin plus one or two single supplements – vitamin D in winter, magnesium for sleep, zinc during a cold. Each product may look modest on its own, but the same nutrient often appears in several of them. A multivitamin with 10 mg of zinc and a separate 25 mg zinc tablet already add up to 35 mg, above the EU upper limit of 25 mg per day.

The calculator recognises vitamins A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E and K, and the minerals calcium, magnesium, iron, zinc, selenium, iodine, copper, manganese, chromium and molybdenum. English and Dutch names, common forms (such as cholecalciferol, pyridoxine or methylcobalamin) and short notations like “B6” or “D3” are understood.

How the totals are calculated

  • Units are converted to the unit of the reference value: mg, µg or g, and IU for vitamins A, D and E (1 µg vitamin D = 40 IU).
  • Compounds such as “magnesium citrate 750 mg” are converted to the elemental mineral, because the label weight of a compound is not the amount of magnesium. When a label already says “magnesium (as citrate) 200 mg”, the 200 mg is used as is.
  • Folate is counted as folic acid for the upper limit and converted to dietary folate equivalents (1 µg folic acid = 1.7 µg DFE) for the reference intake.
  • Each nutrient is compared with the US RDA or AI and UL, and with the EU PRI or AI and UL from EFSA.

Reading the result

A percentage above 100% of the reference intake is not a problem in itself; reference intakes are the amount that covers the needs of almost everyone in a group. The upper limit is the highest daily intake that is unlikely to cause harm over the long term. Totals above an upper limit are highlighted, as are nutrients that come from more than one product.

Remember that your diet also provides vitamins and minerals. Only the upper limits for magnesium, folic acid, niacin and vitamin E (US) are specific to supplements and fortified foods; the others apply to your total intake from all sources.

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Frequently asked questions

How do I enter a multivitamin?

Write the product name, a colon and the nutrients separated by commas, for example “Multivitamin: vitamin D 10 µg, zinc 10 mg, vitamin B6 2 mg”.

Why does magnesium citrate show a lower amount?

Magnesium citrate is about 16% magnesium. 750 mg of the compound contains roughly 121 mg of elemental magnesium, which is what the reference values are based on.

Why are the US and EU limits different?

The two authorities evaluated the evidence at different times and with different safety margins. For vitamin B6 the EU set 12 mg per day in 2023, while the US limit is 100 mg.

Does exceeding the upper limit mean I am overdosing?

Not necessarily, but the risk of side effects rises above the upper limit, especially over months or years. Discuss amounts above the limit with your doctor or pharmacist.

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