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Magnesium intake calculator: how much per day

Short answer

The US Recommended Dietary Allowance for magnesium is 400 mg a day for men aged 19–30 and 420 mg from 31, and 310 mg for women aged 19–30 and 320 mg from 31. The upper limit of 350 mg a day for anyone 9 and over applies only to magnesium from supplements and medicines, not to what you get from food and water.

Last reviewed 28 October 20263 published sourcesNot medical advice

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Magnesium intake calculator

US Dietary Reference Intakes for magnesium from age 1, by age, sex, pregnancy and breastfeeding.

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Magnesium: daily RDA by age and sex
AgeFemaleMaleUpper limit
1–3 years80 mg80 mg65 mg
4–8 years130 mg130 mg110 mg
9–13 years240 mg240 mg350 mg
14–18 years360 mg410 mg350 mg
19–30 years310 mg400 mg350 mg
31–50 years320 mg420 mg350 mg
51–70 years320 mg420 mg350 mg
71+ years320 mg420 mg350 mg
Recommended Dietary Allowances (mg a day) and upper limits for supplemental magnesium only, from the National Academies' DRI summary tables (NASEM, 2019 (DRI tables)).
Magnesium in pregnancy and breastfeeding
AgePregnancyBreastfeedingUpper limit
14–18 years400 mg360 mg350 mg
19–30 years350 mg310 mg350 mg
31–50 years360 mg320 mg350 mg

Where the numbers come from

The magnesium RDAs were set by the Institute of Medicine in 1997 (IOM, 1997 (magnesium)). The National Academies' current summary tables list them alongside the upper limits, with the note that the magnesium upper limits represent intake from a pharmacological agent only and do not include intake from food and water (NASEM, 2019 (DRI tables)).

US food and supplement labels use a single Daily Value of 420 mg (FDA Daily Values), the amount for men aged 31 and over.

Related tools

For other minerals, see the calcium intake calculator and the potassium intake calculator. For a daily food target beyond minerals, try the fiber intake calculator.

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Common questions

How much magnesium do I need a day?

Adult men need 400–420 mg a day and adult women 310–320 mg, with the higher figure from age 31. In pregnancy it is 350 mg at ages 19–30.

What is the upper limit for magnesium?

350 mg a day from age 9 and 110 mg at ages 4–8. The limit covers magnesium from supplements and medicines only; magnesium in food and water does not count toward it.

Why is the magnesium upper limit lower than the RDA?

Because they measure different things. The RDA (for example 420 mg for a man over 30) is your total from food and supplements, while the 350 mg upper limit counts only supplements and medicines. Getting more than 350 mg from food does not put you over the limit.

Sources

Figures on this page were checked against these publications on 28 October 2026.

  1. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium. Washington, DC: The National Academies Press; 2019. Appendix J: Dietary Reference Intakes Summary Tables. doi.org/10.17226/25353
  2. Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: The National Academies Press; 1997. doi.org/10.17226/5776
  3. U.S. Food and Drug Administration. Daily Value on the Nutrition and Supplement Facts labels. Content current as of 5 March 2024. www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels

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