Daily Magnesium Intake — RDA for Men, Women and Teens

The magnesium RDA is 400 to 420 mg a day for men and 310 to 320 mg for women, and the step between the two figures happens at age 31 — not at 50, where most tables put it. Pick your life stage below, then check the table for the exact age break.

The RDA table, with the real age breaks

Life stage	Magnesium per day
Children 4 to 8	130 mg
Ages 9 to 13	240 mg
Males 14 to 18	410 mg
Females 14 to 18	360 mg
Men 19 to 30	400 mg
Men 31 and older	420 mg
Women 19 to 30	310 mg
Women 31 and older	320 mg
Pregnancy 19 to 30	350 mg
Pregnancy 31 to 50	360 mg
Lactation	310 to 320 mg

The selector above groups adults as 19 to 50 and 51-plus, which is the common layout across nutrients. For magnesium that grouping hides the actual boundary: the DRIs move the male figure from 400 to 420 mg at 31, and the female figure from 310 to 320 mg at the same point. If you are between 31 and 50, use the table rather than the dropdown.

Male teenagers are the surprise in the other direction. At 410 mg, a 16-year-old boy needs more magnesium than a 25-year-old man — growth, not body size, drives it.

The 350 mg upper limit is not what it looks like

This is the most misread number in magnesium guidance. The tolerable upper intake level for adults is 350 mg a day, which is below the RDA of 420 mg. That looks like a contradiction until you read the footnote the National Academies attach to it: the magnesium UL represents intake from a pharmacological agent only and does not include intake from food and water.

So the two numbers answer different questions. Eat 420 mg of magnesium from beans, seeds and greens: correct. Add a 400 mg supplement on top: over the ceiling for the supplemental form, where the limiting effect is osmotic diarrhea rather than any harm to magnesium status.

Where the label number comes from

The FDA Daily Value for magnesium is 420 mg, the highest adult RDA, applied to everyone over age 4. A 35-year-old woman with a 320 mg target hits her full requirement at roughly 76% DV, so the percentage on a package understates how far a serving takes her. As with every nutrient on the Nutrition Facts panel, convert the percentage to milligrams before comparing.

What the mineral does, and where it is

Magnesium is a cofactor in hundreds of enzyme reactions — energy production, muscle and nerve function, blood glucose control, blood pressure regulation. About half the body’s magnesium sits in bone, with another quarter in muscle, which is why it belongs in the same conversation as calcium. See the daily calcium intake numbers.

The food sources are consistent and unglamorous:

• Seeds: pumpkin, chia, sunflower.
• Nuts: almonds, cashews, peanuts.
• Legumes and whole grains, including black beans and oats.
• Leafy greens and dark chocolate.

Refining removes most of the magnesium from grains, which is the mechanical reason a diet built on packaged food runs low without anyone noticing. The same foods carry potassium — see the daily potassium intake figures — and the two minerals are often discussed together in the context of muscle cramps, which is covered on magnesium and potassium deficiency cramps.

This content is informational and does not replace evaluation by a physician or registered dietitian.