How Much Magnesium Per Day? Daily Needs by Age, Sex and Goal
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Most adults need 310–420 mg of magnesium per day from food and supplements combined. Men need 400–420 mg and women 310–320 mg (more in pregnancy). Supplements on their own shouldn't exceed 350 mg a day unless a doctor advises it, because higher amounts commonly cause diarrhea.
Magnesium is involved in more than 300 enzyme reactions, from turning food into energy to keeping your heartbeat steady. Yet the right amount isn't one number. It depends on your age, your sex, whether you're pregnant, and whether you're counting food, supplements, or both.
So how much magnesium per day do you actually need? This guide gives you your exact daily target, explains the one limit that applies only to supplements, and helps you decide whether you need a supplement at all.
Daily magnesium needs by age and sex
The Recommended Dietary Allowance (RDA) is the amount that covers the needs of nearly all healthy people. It includes magnesium from all sources: food, drinks and supplements.
| Age | Male | Female | Pregnancy | Breastfeeding |
|---|---|---|---|---|
| 1–3 years | 80 mg | 80 mg | – | – |
| 4–8 years | 130 mg | 130 mg | – | – |
| 9–13 years | 240 mg | 240 mg | – | – |
| 14–18 years | 410 mg | 360 mg | 400 mg | 360 mg |
| 19–30 years | 400 mg | 310 mg | 350 mg | 310 mg |
| 31+ years | 420 mg | 320 mg | 360 mg | 320 mg |
Source: NIH Office of Dietary Supplements, based on the National Academies' Dietary Reference Intakes.
The 350 mg limit applies to supplements only
The Tolerable Upper Intake Level (UL) for magnesium is 350 mg per day for adults. It's lower than the RDA, which confuses many people.
The UL covers only magnesium from supplements and medications, not from food. Magnesium in food is absorbed gradually and the kidneys remove what you don't need. A concentrated supplement dose, on the other hand, pulls water into the gut. That's why the first sign of "too much" is usually diarrhea, nausea or cramping rather than anything dangerous.
So a healthy adult could reasonably get 250 mg from food and add a 200 mg supplement. The total of 450 mg is above the RDA, but the supplement portion stays under 350 mg.
Who should be careful: People with reduced kidney function can't clear extra magnesium well, and very high intake can build up in the blood. Check with your doctor before supplementing if you have kidney disease.
How to tell if you're getting enough
There's no reliable home test, and a standard blood test doesn't show the whole picture because most magnesium is stored in bone and cells, not in the blood. A practical approach:
- Estimate your food intake. Log a typical day in a free nutrition app and look at the magnesium total.
- Look at risk factors. Low intake is more likely if you rarely eat greens, legumes, nuts or whole grains, drink alcohol heavily, have a digestive condition such as Crohn's or celiac disease, have type 2 diabetes, or take certain medications.
- Talk to your clinician if you have symptoms such as muscle cramps, fatigue or an irregular heartbeat. These have many causes, so don't assume it's magnesium.
Medications that affect magnesium
- Proton pump inhibitors (such as omeprazole) used for many months can lower magnesium levels.
- Some diuretics increase how much magnesium you lose in urine.
- Certain antibiotics (tetracyclines, quinolones) and osteoporosis drugs (bisphosphonates) bind to magnesium. Take them at least 2 hours apart from a magnesium supplement.
Foods that cover most of your daily needs
You can often close the gap without a pill. Typical amounts per serving:
| Food | Serving | Magnesium |
|---|---|---|
| Pumpkin seeds, roasted | 1 oz (28 g) | about 156 mg |
| Chia seeds | 1 oz (28 g) | about 111 mg |
| Almonds, dry roasted | 1 oz (28 g) | about 80 mg |
| Spinach, boiled | ½ cup | about 78 mg |
| Cashews, dry roasted | 1 oz (28 g) | about 74 mg |
| Black beans, cooked | ½ cup | about 60 mg |
| Plain yogurt | 8 oz | about 42 mg |
| Brown rice, cooked | ½ cup | about 42 mg |
A handful of pumpkin seeds, a portion of beans and a side of spinach already add up to around 290 mg.
Choosing a magnesium supplement dose
If you decide to supplement, these steps keep it simple:
- Start low. 100–200 mg of elemental magnesium per day is enough for most people topping up a diet.
- Read the elemental amount. "500 mg magnesium glycinate" on the front may contain only about 70 mg of actual magnesium. The Supplement Facts panel lists the elemental figure.
- Split larger doses. Two smaller doses are easier on the stomach than one large one.
- Take it with food if you notice any stomach upset.
- Pick the form for your goal. Glycinate tends to be gentle, citrate is well absorbed but can loosen stools, and oxide is cheap but poorly absorbed. Our magnesium glycinate vs citrate comparison goes deeper.
Signs you've taken too much
From supplements, the most common signs are diarrhea, nausea and abdominal cramps. These usually stop when you lower the dose.
Serious toxicity (low blood pressure, muscle weakness, confusion, irregular heartbeat) is rare and mostly linked to very large doses of magnesium-containing laxatives or antacids, often in people with kidney problems. Seek medical care if you notice these symptoms.
The bottom line
Aim for the RDA for your age and sex from all sources: about 400–420 mg for men and 310–320 mg for women. Get as much as you can from food. If you add a supplement, keep it at or below 350 mg a day, check the elemental magnesium on the label, and talk to your doctor first if you have kidney disease or take medications that interact with magnesium.
Where to buy
We don't accept payment for rankings. These links open a store search filtered to the form we discuss, so you can compare brands using the checklist above.
Magnesium glycinate capsules
A good default for daily top-ups. Look for the elemental magnesium amount on the label, ideally 100–200 mg per serving.
Magnesium citrate powder
Easy to split into smaller doses. Also has a mild laxative effect, which some people want and others don't.
Frequently asked questions
Is 500 mg of magnesium a day too much?
From food, no. Your kidneys clear the excess. From supplements, 500 mg is above the 350 mg upper limit set for adults and often causes loose stools or cramps. Only take that much if a clinician recommends it.
Can I get enough magnesium from food alone?
Many people can. A day that includes leafy greens, beans, nuts or seeds and whole grains can reach 300–400 mg. US survey data suggest about half of adults fall short, mainly because of low intake of these foods.
Should I take magnesium every day?
If you're filling a regular gap in your diet, daily use at or below 350 mg is considered safe for healthy adults. People with kidney disease should not take magnesium supplements without medical supervision.
What time of day should I take magnesium?
Timing matters less than consistency. Many people take it in the evening, and taking it with food reduces stomach upset.
Sources
This page is for education and is not a substitute for advice from your doctor. Read our medical disclaimer.