How Much Magnesium Should You Take a Day? Amounts by Age, Sex and Source

Most adults need 310 to 420 mg of magnesium a day, and that total counts food, drinks and supplements together. Women need 310 to 320 mg and men 400 to 420 mg, depending on age, according to the NIH Office of Dietary Supplements (ODS). The supplement share is usually much smaller. It only has to fill the gap your diet leaves, and magnesium from supplements and medicines should stay at or below 350 mg a day for adults, a limit that doesn't count food at all.

So the real answer to "how much magnesium should I take?" is a two-part number: your daily target, and the slice of it that comes from a bottle. This guide gives you both, by age and sex, plus the label-reading trick that stops a big front-of-pack number from fooling you. If you want the why before the how much, start with what magnesium does in your body.

How much magnesium do you need per day?

As an adult, your Recommended Dietary Allowance (RDA) for magnesium is 310 to 420 mg a day, set by the Food and Nutrition Board and published by NIH ODS. The target climbs through childhood to 410 mg for teenage boys and 360 mg for teenage girls, then settles at 420 mg for men and 320 mg for women from age 31 onward. The RDA covers everything you eat, drink and take. The upper limit (UL) in the last column covers supplements and medicines only, which is why it can sit below the RDA without contradicting it.

Magnesium RDAs (total intake from food, drinks and supplements) and upper limits (supplements and medicines only), mg per day. Source: NIH Office of Dietary Supplements, Tables 1 and 3.

Age	Male	Female	Pregnancy	Breastfeeding	Upper limit from supplements and medicines
0–6 months	30*	30*	n/a	n/a	Not established
7–12 months	75*	75*	n/a	n/a	Not established
1–3 years	80	80	n/a	n/a	65
4–8 years	130	130	n/a	n/a	110
9–13 years	240	240	n/a	n/a	350
14–18 years	410	360	400	360	350
19–30 years	400	310	350	310	350
31–50 years	420	320	360	320	350
51+ years	420	320	n/a	n/a	350

*Infant values are Adequate Intakes, based on what healthy breastfed infants take in. Europe uses a different yardstick: the European Food Safety Authority (EFSA) set an Adequate Intake of 350 mg a day for men and 300 mg for women in 2015 (an intake target, not a limit), with no extra amount for pregnancy or breastfeeding. Different method, same ballpark.

How much magnesium per day for a woman?

An adult woman needs 310 mg of magnesium a day from ages 19 to 30 and 320 mg from age 31 on, including after 50. Pregnancy raises the target to 350 mg (ages 19 to 30) or 360 mg (ages 31 to 50). Teens aged 14 to 18 need 360 mg, or 400 mg when pregnant. Breastfeeding brings the target back to the non-pregnant level: 310 or 320 mg for adults and 360 mg for teens. The supplement limit doesn't change during pregnancy or breastfeeding.

How much magnesium should you take as a supplement?

Aim to cover the gap between what your food supplies and your RDA, and keep all supplemental magnesium at or under 350 mg a day. The supplement is a top-up, not the whole target. Plenty of people do have a gap: an analysis of NHANES 2013–2016 data found that 48% of Americans of all ages get less magnesium from food and drinks than their Estimated Average Requirement, the intake that meets the needs of half of healthy people. Men 71 and older and teenagers are the most likely to fall short (NIH ODS).

Here's the arithmetic with real averages. In NHANES 2003–2006, adults who didn't use magnesium supplements got about 234 mg (women) and 268 mg (men) from food alone. Use those figures as an example, not as your own intake:

• A 40-year-old woman: a 320 mg RDA minus 234 mg from food leaves a gap of about 86 mg.
• A 40-year-old man: a 420 mg RDA minus 268 mg from food leaves a gap of about 152 mg.

Both gaps fit comfortably under the supplement limit, and neither calls for a heroic dose. Your own number depends on what you eat, and age plays a part too: older adults tend to eat and absorb less magnesium while their RDA holds steady, so the gap can widen with age. Our guide to foods high in magnesium lists milligrams per serving so you can estimate yours. Load up on seeds, beans and leafy greens and the gap shrinks; skip them and it grows.

The 350 mg limit dates from 1997, when the US Institute of Medicine set it with diarrhea as the limiting effect. A 2023 perspective in Advances in Nutrition argues it is due for re-evaluation, but for now it remains the reference to plan within.

What does "elemental magnesium" mean on a label?

Elemental magnesium is the magnesium itself, without the compound it's bound to, and it's the number that counts toward your RDA and the upper limit. Magnesium in a supplement always comes paired with a partner: glycinate, citrate, oxide, gluconate and so on. The Supplement Facts panel declares the elemental magnesium, not the weight of the whole compound (NIH ODS).

The front of the bottle is where things get creative. A headline like "1,000 mg magnesium glycinate" describes the compound, and the magnesium inside is only a fraction of that. Flip the bottle and read the Magnesium line on the panel; that's your dose. The %DV beside it is calculated against a Daily Value of 420 mg for adults and children 4 and older, which makes it handy for quick comparisons even if your own RDA is lower.

How much magnesium glycinate should you take?

The same amount as any other form: enough elemental magnesium to cover your gap, with all supplements and medicines together staying within the upper limit. Glycinate counts toward the limit exactly like citrate or oxide, because the glycine partner doesn't come with a separate allowance. So when you ask how many mg of magnesium glycinate per day, answer in elemental milligrams from the Supplement Facts panel, not in compound weight. Our breakdown of magnesium bisglycinate vs glycinate walks through the compound math, and magnesium glycinate vs citrate compares the two most popular forms.

For a real-world reference point, a 2025 randomized, placebo-controlled trial assigned 155 adults aged 18 to 65 who reported poor sleep to 250 mg of elemental magnesium as bisglycinate (77 people) or a placebo (78) every day. After four weeks, Insomnia Severity Index scores fell 3.9 points with magnesium versus 2.3 with placebo (p = 0.049), a small effect (d = 0.2), and exploratory analyses pointed to bigger improvements in people who ate less magnesium at the start. For how glycinate compares with every other form, see our guide to the types of magnesium.

Do antacids, laxatives and other supplements count?

Yes. The 350 mg upper limit covers magnesium from all dietary supplements and medicines, so every magnesium-containing product you use goes into the same total. Some carry a lot more than you'd guess:

Magnesium sources and whether each counts toward the 350 mg adult upper limit. Source: NIH Office of Dietary Supplements.

Source	Elemental magnesium	Counts toward the limit?
Phillips' Milk of Magnesia (laxative)	500 mg per tablespoon	Yes
Extra-strength Rolaids (antacid)	55 mg per tablet	Yes
Tums (antacid)	None	Nothing to count
Multivitamin or other supplement listing magnesium	See the Supplement Facts panel	Yes
Food and drinks	Varies	No

Laxative directions can go well above the upper limit, and ODS notes that some of that magnesium isn't absorbed because of the laxative effect. For everyday use, add up the Magnesium line on your multivitamin, any sleep or electrolyte powder that lists magnesium, and any antacids before you pick a standalone supplement dose.

Other minerals can get in the way, too. One study cited by ODS found that very high doses of zinc from supplements, 142 mg a day, can interfere with magnesium absorption and disrupt the body's magnesium balance. That's a very high zinc intake, so it mainly matters if you take a standalone high-dose zinc product.

Who should check with a clinician first?

Most healthy adults can work out their number with the steps above. A few situations call for a quick conversation with your doctor or pharmacist before you start (NIH ODS):

• Kidney disease or reduced kidney function. Healthy kidneys clear extra magnesium. When they can't, the risk of magnesium building up rises.
• Osteoporosis medicines. Magnesium can reduce absorption of oral bisphosphonates such as alendronate, so take them at least 2 hours apart.
• Tetracycline or quinolone antibiotics. Doxycycline, ciprofloxacin and related drugs should be taken at least 2 hours before or 4 to 6 hours after a magnesium supplement.
• Diuretics and long-term acid reducers. Loop and thiazide diuretics can increase magnesium loss, potassium-sparing diuretics reduce it, and proton pump inhibitors taken for more than about a year can cause low magnesium. Your prescriber may want to check your levels.
• Pregnancy and breastfeeding. Pregnancy raises your RDA, and a prenatal vitamin that lists magnesium counts toward the same supplement limit.
• Children. Upper limits are 65 mg a day for ages 1 to 3 and 110 mg for ages 4 to 8, so adult products and servings aren't for kids without a pediatrician's advice.

Where a 200 mg liquid serving fits

Once you know your gap, a measured serving makes the math easy. Infinite Labs Liposomal Magnesium+ provides 200 mg of elemental magnesium per 10 mL serving (2 teaspoons), from magnesium bisglycinate and magnesium gluconate, in a liposomal liquid made with sunflower lecithin.

One serving sits under the 350 mg adult limit for supplements and medicines on its own, leaving 150 mg of headroom for anything else in your routine, such as a multivitamin or an occasional antacid. For the 40-year-old man in our example, one serving covers his roughly 152 mg gap. For the 40-year-old woman, it more than covers her roughly 86 mg gap, and both still keep their supplemental totals well under the limit.

If you'd rather drink your magnesium than swallow another capsule, Magnesium+ is a strong pick. Shake the bottle, measure 10 mL and stir it into water or juice once a day, or take it as your healthcare professional directs. Each bottle holds 18 servings; store it somewhere cool and dry and use it within 30 days of opening. It's third-party tested and made in GMP-certified facilities, and certificates of analysis are available on request.

Quick answers

What are the signs of too much magnesium?

Diarrhea is usually the first sign, often with nausea and abdominal cramping, when supplements or medicines push intake too high. Serious magnesium toxicity is rare. It has been linked to very large doses of magnesium-containing laxatives and antacids, typically more than 5,000 mg a day, and the risk rises when kidney function is impaired. Our guide to how much magnesium is too much covers the details, including where 500 mg fits.

What are the signs your body needs more magnesium?

Early signs of magnesium deficiency include loss of appetite, nausea, vomiting, fatigue and weakness, according to NIH ODS. Those overlap with plenty of everyday causes, so they can't confirm a deficiency on their own. Symptomatic deficiency from diet alone is uncommon in healthy people because the kidneys hold on to magnesium when intake runs low. If you have symptoms, talk to a clinician rather than self-diagnosing.

What vitamins cannot be mixed with magnesium?

The NIH ODS interaction list for magnesium names medicines, not vitamins. The ones to manage are very high-dose zinc (covered with other supplements above) and the bisphosphonates and antibiotics in the clinician list. A pharmacist can check your full list in a few minutes.

The takeaway

Your magnesium number takes about two minutes to work out:

1. Find your RDA in the table above: 310 to 320 mg for most women, 400 to 420 mg for most men, more during pregnancy.
2. Estimate what your food supplies with the magnesium foods guide linked above.
3. Fill the gap with a supplement, keeping magnesium from all supplements and medicines at or under 350 mg a day and reading the elemental number on every label.

Want to compare forms before you choose? The types of magnesium guide linked above lays them side by side.

Sources

• NIH Office of Dietary Supplements: Magnesium, Fact Sheet for Health Professionals (updated January 6, 2026).
• EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on Dietary Reference Values for magnesium. EFSA Journal, 2015.
• Costello R, Rosanoff A, Nielsen F, West C. Perspective: Call for Re-evaluation of the Tolerable Upper Intake Level for Magnesium Supplementation in Adults. Advances in Nutrition, 2023.
• Schuster J et al. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep, 2025.

This article is educational and is not medical advice. Infinite Labs Liposomal Magnesium+ is not intended to diagnose, treat, cure, or prevent any disease.