How Much Magnesium Per Day? 310–420 mg RDA, 200–350 mg
Adults need 310–420 mg of magnesium a day from food and supplements together (the NIH RDA: 310–320 mg for women, 400–420 mg for men). From a supplement on its own, 200–350 mg of elemental magnesium a day, with food, stays inside the 350 mg upper limit for magnesium from supplements. Sleep trials of plain magnesium used 250–729 mg, amounts studied and not recommendations.
Best magnesium to hit your dose
- Buy on Amazon for Nature Made Magnesium Glycinate
Our pick: 200 mg, on a testing list
Nature Made Magnesium Glycinate $0.73 a day at list price (200 mg)
200 mg of magnesium in 2 capsules, all glycinate. USP Verified, which checks the dose on the label. One serving a day stays well under the limit.
- Check price on Amazon for Doctor’s Best High Absorption Magnesium
You want to set the dose by the tablet
Doctor’s Best High Absorption Magnesium $0.20 a day at list price (200 mg)
A big bottle you can dose by the tablet: 240 tablets with 100 mg of magnesium each. One serving is 2 tablets (200 mg). The label allows 2 servings a day (400 mg), which is over the 350 mg limit for pills, so take 3 tablets at most. It is on no public testing list.
- Check price on Amazon for Thorne Magnesium Glycinate
A smaller capsule, on a testing list
Thorne Magnesium Glycinate $0.29 a capsule (120 mg) at list price
120 mg a capsule, so 1 or 2 a day. On NSF/ANSI 173. Its label allows up to 4 capsules (480 mg), which is over the limit.
- Check price on Amazon for Vitamin Shoppe Magnesium Glycinate 400 mg
Another big bottle of tablets
Vitamin Shoppe Magnesium Glycinate 400 mg
A big bottle you can dose by the tablet: 135 tablets with 133 mg of magnesium each. Its label serving (3 tablets, 400 mg) is over the 350 mg limit for pills, so take 1 or 2 tablets. It is on no public testing list, and we found no list price.
Costs are each brand’s own list price for one pack, checked October 14, 2026.
Check which number your label shows. The limit is a ceiling, not a target; many adults need less from a pill, or none. The “Magnesium” line on the Supplement Facts panel is the magnesium itself. The big number on the front is often the whole compound; for glycinate that is about 7 times the magnesium. And follow the directions. We checked 833 magnesium labels: the median serving was 250 mg, but the median day as directed came to 399 mg, above the limit. How to read the label.
A summary of NIH guidance and published research, not medical advice. Ask your doctor before taking magnesium if you have kidney disease or take prescription medicines.
How Much Magnesium Per Day?
Adult women need 310–320 mg of magnesium a day and adult men need 400–420 mg, from all sources combined (NIH RDA). The NIH upper limit for magnesium from supplements is 350 mg a day. It applies to supplements and medicines only, not food. Count every serving the label tells you to take, and stay at or under that ceiling. Some trials used more; the table further down shows the amounts studied.
Many people fall short from food alone: 48% of Americans get less magnesium from food and drinks than they need (NIH). That is the gap a supplement fills. You do not need a supplement to reach the whole RDA.
Recommended Daily Allowance (RDA)
These are the total daily magnesium needs from all sources (food and supplements), set by the National Institutes of Health:
| Age | Men | Women | Pregnant | Nursing |
|---|---|---|---|---|
| 14–18 years | 410 | 360 | 400 | 360 |
| 19–30 years | 400 | 310 | 350 | 310 |
| 31–50 years | 420 | 320 | 360 | 320 |
| 51 years and over | 420 | 320 | — | — |
Children: 80 mg (1–3 years), 130 mg (4–8 years), 240 mg (9–13 years), boys and girls alike. The “% Daily Value” on labels is based on 420 mg.
The upper limit for magnesium from supplements
| Age | Upper limit |
|---|---|
| 1–3 years | 65 mg |
| 4–8 years | 110 mg |
| 9 years and over, including pregnancy and breastfeeding | 350 mg |
For some ages the limit is lower than the RDA. That is not a mistake: the RDA counts food, and the limit counts only pills and medicines. The UK’s NHS says 400 mg or less a day from supplements is unlikely to cause harm; NIH’s limit is the stricter of the two.
Find your magnesium dose
Answer a few questions for an estimate based on the NIH RDA. It's an estimate, not a prescription — talk to your clinician.
Understanding Elemental vs Compound Weight
This is the most common source of dosing mistakes. Magnesium in a pill is always bonded to something else, such as glycinate, citrate or oxide. A label can show the weight of that whole compound, or only the magnesium in it. The “Magnesium” line on the Supplement Facts panel is the magnesium itself (the elemental amount), not the weight of the whole compound (NIH).
How to read the label: find the line that says “Magnesium,” with the form in brackets, for example “Magnesium (as Magnesium Bisglycinate) 200 mg.” That mg is the magnesium your body counts. If the panel also lists a compound line (like “Magnesium Citrate 800 mg”), ignore it for dosing.
Gummies are where this bites hardest. In April 2026, the advertising watchdog NAD reviewed a gummy sold as “Magnesium Glycinate Gummies 200 mg Per Serving.” Its Supplement Facts panel showed 22 mg of magnesium. NAD recommended changing the 200 mg claim, and the brand agreed (NAD decision). The case was brought by Pharmavite, the maker of Nature Made, our pick. No magnesium gummy we score reaches 300 mg a serving.
The labels we checked show the same gap: of 216 labels that put a magnesium number in the product name, 28 name a bigger number than the magnesium on the panel.
| Item | Value (%) |
|---|---|
| Oxide | 60% |
| Citrate | 16% |
| Malate | 15% |
| Glycinate | 14% |
| Taurate | 9% |
| L-threonate | 7.2% |
| Compound | Compound for 300 mg of magnesium |
|---|---|
| Oxide | 500 mg |
| Citrate | 1,900 mg |
| Malate | 2,000 mg |
| Glycinate | 2,150 mg |
| Taurate | 3,350 mg |
| L-threonate | 4,150 mg |
Small studies found the citrate, aspartate, lactate and chloride forms absorbed better than oxide and sulfate (NIH). NIH says nothing about glycinate either way. Oxide is the form the constipation trials tested (see the table below).
Amounts Used in Published Trials
These are the magnesium amounts reported in reviews of published trials. They are the amounts studied, not recommendations, and some are above the NIH supplemental limit. This is research, not advice for any condition.
| Topic | Amount studied | What the review found |
|---|---|---|
| Sleep | 250–729 mg a day, 3 to 8 weeks | 3 trials in older adults, 151 people: they fell asleep about 17 minutes faster than on placebo; total sleep time did not change significantly; low to very low quality evidence (Mah 2021). A 2025 trial of 250 mg as glycinate in 155 adults found a small benefit (Schuster 2025). |
| Blood pressure | Median 365 mg a day, median 12 weeks | 38 trials, 2,709 people: top number down about 2.8 points, bottom number about 2.1. No significant change in people with normal blood pressure (Argeros 2025). |
| Migraine | Usually above the limit | Mixed. A 2025 review found fewer attacks (Talandashti 2025); a 2026 review found the drop in how often attacks came was not significant, but magnesium did lower how bad attacks were (Peng 2026). Neurology groups rate it “probably effective”; because the usual dose is over the limit, NIH says to use it only with a doctor. |
| Constipation | Magnesium oxide, as a laxative | 2 trials: 68% got better on magnesium oxide vs 19% on placebo (van der Schoot 2023). |
| Leg cramps | Various; 300 mg as bisglycinate in one pregnancy trial | Unlikely to help typical night cramps in older adults (Cochrane, Garrison 2020). In pregnancy, one trial of 300 mg of magnesium bisglycinate a day for 4 weeks found fewer cramps (Supakatisant 2015); other pregnancy trials did not agree. |
Magnesium amounts in sleep studies
Sleep trials of plain magnesium used 250 to 729 mg of magnesium a day, including a 2025 trial of 250 mg as glycinate (Schuster 2025). Trials of magnesium L-threonate are separate: they used 1 to 2 g of the compound, about 72 to 144 mg of magnesium. In older adults, one trial gave 500 mg a day, as magnesium oxide, for 8 weeks to 46 older adults with insomnia (Abbasi 2012). One gave 320 mg a day as citrate for 7 weeks to adults over 51 who slept poorly; sleep scores improved about as much on placebo (Nielsen 2010). The third built up to 729 mg a day over 20 days in 12 adults aged 60 to 80 (Held 2002). These are amounts studied, not recommendations. Pooled, those three gave small results (Mah 2021, see the table above). The 2025 trial gave 250 mg as glycinate for 4 weeks to 155 adults who slept poorly, a dose under the limit; the benefit was small (Schuster 2025). Some trial amounts are above the supplement limit, so talk to your doctor before taking more. The amount and form in each sleep trial: magnesium amounts in sleep studies.
Older adults
The RDA does not change after 30: 420 mg a day for men and 320 mg for women. Older adults tend to eat less magnesium, absorb less of it and lose more in urine, and some common medicines lower it further (NIH).
How much magnesium seniors need → kidneys, heartburn pills, water pills and which form to take.
When to Take Magnesium
- Timing: Any time of day works. Some people take glycinate in the evening. Follow the label.
- With food: If it upsets your stomach, try taking it with a meal.
- Antibiotics: take tetracyclines (such as doxycycline) or quinolones (such as ciprofloxacin) at least 2 hours before or 4 to 6 hours after magnesium (NIH).
- Osteoporosis drugs: Bisphosphonates such as alendronate: take them at least 2 hours apart from magnesium (NIH).
- Above the ceiling: Do not go above the everyday ceiling without your doctor's advice.
What magnesium labels tell you to take
We read the Supplement Facts panel and the directions of 833 magnesium labels in the NIH Dietary Supplement Label Database. The median serving was 250 mg, under the limit. The median day as directed was 399 mg, over it. The difference is the directions: a label that says “take 2 capsules twice a day” is four servings, and nothing on the front of the bottle does that math for you.
So check two numbers on the panel: the magnesium per serving, and how many servings a day the label tells you to take. Multiply them, then add any magnesium in your multivitamin. Keep the total from supplements under the limit. A 200 mg serving taken once a day, like our pick, does that easily.
| Measure | Low 10% | Middle | High 10% |
|---|---|---|---|
| Per serving | 100 mg | 250 mg | 500 mg |
| Per day, as directed | — | 399 mg | 500 mg |
| Servings a day | Labels | Share |
|---|---|---|
| 1 | 592 | 72% |
| 2 | 141 | 17% |
| 3 | 76 | 9% |
| 4 | 15 | 2% |
| 5 | 1 | under 1% |
| 6 | 1 | under 1% |
| Main form | Middle serving | High 10% |
|---|---|---|
| Citrate | 250 mg | 500 mg |
| Oxide | 300 mg | 500 mg |
| Glycinate | 233 mg | 400 mg |
| Malate | 355 mg | 480 mg |
| Aspartate | 133 mg | 400 mg |
705 of the 825 labels with an amount (85%) put 420 mg or less in one serving. The total for the day is what matters, and that depends on the directions.
Which form the market actually sells
Citrate and oxide lead by far. Glycinate, the form most guides talk about, is named on far fewer labels. A label is counted once for each form of magnesium its Supplement Facts panel names, so a label with two forms counts under both.
| Item | Value |
|---|---|
| Citrate | 351 |
| Oxide | 244 |
| Glycinate or bisglycinate | 94 |
| Aspartate | 81 |
| Malate | 61 |
| Gluconate | 43 |
We checked 833 of the 39,884 magnesium labels in the database, read August 29, 2026. It shows what labels say, not what is in the bottle or what you absorb. When we split the labels into two random halves, both gave the same middle values.
Why the trials used more than the limit
The NIH limit counts magnesium from supplements, and the sleep trials above used up to 729 mg a day.
Too much magnesium from pills most often causes diarrhea, sometimes with nausea and stomach cramps. That is why the limit is set where it is (NIH). A trial can go above the limit because its researchers watch for that side effect. At home, the limit is the number to use, unless your doctor tells you otherwise.
- Food does not count. The limit covers supplements and medicines only. Your body controls how much magnesium it takes in from food.
- Kidney disease is the exception that matters. If you have kidney disease, ask your doctor before you take magnesium. Weak kidneys cannot clear the extra, so it can build up (NIH).
- Real toxicity is rare. It has mostly come from very large doses of magnesium laxatives or antacids, usually more than 5,000 mg a day, or from kidney failure (NIH). Signs include low blood pressure, nausea, flushing and muscle weakness.
- If one dose upsets your stomach, try two smaller doses with meals.
How Much Magnesium Are You Getting from Food?
Nuts, seeds, beans, whole grains and leafy greens are the richest sources. Still, 48% of Americans get less than they need from food and drinks (NIH). Some common foods:
| Food | Magnesium |
|---|---|
| Pumpkin seeds, roasted, 1 ounce | 156 mg |
| Chia seeds, 1 ounce | 111 mg |
| Almonds, dry roasted, 1 ounce | 80 mg |
| Spinach, boiled, ½ cup | 78 mg |
| Cashews, dry roasted, 1 ounce | 74 mg |
| Peanuts, oil roasted, ¼ cup | 63 mg |
| Soymilk, plain or vanilla, 1 cup | 61 mg |
| Black beans, cooked, ½ cup | 60 mg |
| Peanut butter, smooth, 2 tablespoons | 49 mg |
| Potato, baked with skin, 3.5 ounces | 43 mg |
| Brown rice, cooked, ½ cup | 42 mg |
| Yogurt, plain, low fat, 8 ounces | 42 mg |
| Banana, 1 medium | 32 mg |
A blood test for magnesium reflects only a small share of the magnesium in your body, so a normal result does not rule out low levels; some clinicians order an RBC magnesium test instead, though it has limits of its own.
Frequently Asked Questions
How much magnesium should I take per day?
Adults need 310 to 420 mg a day from food and supplements together: 310 to 320 mg for women and 400 to 420 mg for men (NIH). If you take a supplement, keep it at or under the upper limit for magnesium from pills (next question). Food does not count toward that limit.
Is 350 mg the maximum? Is the RDA a limit?
The RDA is a goal for food and supplements together, not a limit. The limit is separate: 350 mg a day of magnesium from supplements and medicines for anyone 9 and older (NIH). Food has no limit, because the body controls how much it absorbs from food.
Is 400 or 500 mg of magnesium too much?
From supplements, both are over NIH’s limit. High doses from pills often cause diarrhea (NIH); the NHS says that happens above 400 mg. Some trials used more. Don’t go over the limit unless your doctor tells you to, and never with kidney disease.
Can I take my magnesium all at once, or should I split it?
Either works for a normal dose. If one dose upsets your stomach, take half with breakfast and half with dinner. Taking it with food can also help.
What amount did the sleep trials use?
Sleep trials of plain magnesium used 250 to 729 mg of magnesium a day, including a 2025 trial of 250 mg as glycinate (Schuster 2025). Trials of magnesium L-threonate are separate: they used 1 to 2 g of the compound, about 72 to 144 mg of magnesium. Some of those amounts are above the supplement limit. These are amounts studied, not advice. Our magnesium dosage for sleep page goes through each trial.
When is the best time to take magnesium?
Any time you will remember. Take it with food if it upsets your stomach, and space it from some antibiotics and osteoporosis drugs. See our full best time to take magnesium guide.
Can you take too much magnesium?
Yes. High doses from supplements often cause diarrhea, sometimes with nausea and cramps (NIH); that is why the limit is set where it is. Dangerous levels are rare and have mostly come from laxatives or antacids giving more than 5,000 mg a day, or from kidney failure.
What's the difference between elemental magnesium and compound weight?
Magnesium in a pill is bonded to another molecule, such as glycinate or citrate. Elemental magnesium is the magnesium part. On the Supplement Facts panel, the “Magnesium” line already shows the elemental amount (NIH). The front of the bottle may show the whole compound: 2,000 mg of magnesium glycinate holds only about 280 mg of magnesium.
How many capsules of a “400 mg magnesium glycinate” should I take?
Check the Supplement Facts panel, not the front. If “400 mg” is the compound, each capsule may hold only about 56 mg of magnesium. If the magnesium line says 400 mg per serving, that one serving is already over the limit, so take part of it.
How much magnesium should older adults (seniors) take?
The RDA does not rise after 30: 420 mg a day for men and 320 mg for women. Ask your doctor first if you have kidney disease. Our magnesium for seniors guide covers the medicines and health problems that change the answer.
How much magnesium should a woman take per day?
The RDA for adult women is 310 mg a day (ages 19 to 30) or 320 mg (31 and over), from food and supplements together. In pregnancy it is 350 to 400 mg, depending on age.
Should I take a magnesium supplement while pregnant?
Ask your prenatal provider before taking any supplement, including magnesium. Many prenatal vitamins already contain some.
Bottom line: get what you can from food, and keep magnesium from supplements under the limit. Our pick is Nature Made Magnesium Glycinate, 200 mg a serving, USP Verified.
Related Guides
- How Much Magnesium for Seniors? — same RDA; kidneys and medicines change the answer
- Magnesium side effects and too much magnesium — diarrhea by form, and who must be careful
- Magnesium Forms Compared — which form to choose for your goal
- Best Magnesium Glycinate — dose per capsule, testing and cost
- Magnesium and Sleep — research and products compared
- Magnesium for Muscle Cramps — what the cramp trials found
- All Magnesium Guides
Sources
- NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (updated January 6, 2026; read October 14, 2026). RDA (Table 1), foods (Table 2), upper limit (Table 3), intakes, absorption by form, labels, toxicity, kidney disease, interactions, older adults, migraine.
- Mah J, Pitre T. Oral magnesium supplementation for insomnia in older adults: a systematic review & meta-analysis. BMC Complement Med Ther. 2021. PubMed 33865376
- Abbasi B, et al. The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. J Res Med Sci. 2012. PubMed 23853635
- Nielsen FH, et al. Magnesium supplementation improves indicators of low magnesium status and inflammatory stress in adults older than 51 years with poor quality sleep. Magnes Res. 2010. PubMed 21199787
- Held K, et al. Oral Mg(2+) supplementation reverses age-related neuroendocrine and sleep EEG changes in humans. Pharmacopsychiatry. 2002. PubMed 12163983
- Schuster J, et al. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. Nat Sci Sleep. 2025. PubMed 40918053
- Argeros Z, et al. Magnesium supplementation and blood pressure: a systematic review and meta-analysis of randomized controlled trials. Hypertension. 2025. PubMed 41000008
- Talandashti MK, et al. Effects of selected dietary supplements on migraine prophylaxis: a systematic review and dose-response meta-analysis of randomized controlled trials. Neurol Sci. 2025. PubMed 39404918
- Peng J, et al. Nutritional supplements for migraine prevention: evaluating evidence sufficiency and effect modifiers through network meta-analysis, trial sequential analysis, and meta-regression. Front Nutr. 2026. PubMed 42707444
- van der Schoot A, et al. The effect of food, vitamin, or mineral supplements on chronic constipation in adults: a systematic review and meta-analysis of randomized controlled trials. Neurogastroenterol Motil. 2023. PubMed 37243443
- Supakatisant C, Phupong V. Oral magnesium for relief in pregnancy-induced leg cramps: a randomised controlled trial. Matern Child Nutr. 2015. PubMed 22909270
- Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020. PubMed 32956536
- BBB National Programs, National Advertising Division. Nature’s Truth magnesium glycinate gummies (April 27, 2026).
- NHS. Vitamins and minerals: others (magnesium).
- NIH Dietary Supplement Label Database: label 336938, and 833 magnesium labels read August 29, 2026; our analysis. Product labels and list prices: each brand’s own page, read October 14, 2026. Testing lists searched October 14, 2026.
This page is for information. It is not medical advice.