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Magnesium Dosage Calculator: Daily RDA by Age and Sex

Find your recommended daily magnesium intake (RDA) by age and sex, based on NIH Office of Dietary Supplements guidelines. Includes full table by age group, best supplement form, and top food sources. Instant, no sign-up needed.

🗓️ Updated June 2026 Reviewed by Martín Rodríguez

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Reviewed by: Martín Rodríguez (editorial policy ) · Last reviewed: Jun 20, 2026

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Daily Magnesium Requirement Calculator (RDA by Age & Sex)Find out exactly how much magnesium you need per day. RDA table by age and sex (310–420 mg), top food sources, and supplement guide: glycinate, citrate, malate.How Much Calcium Do You Need Per Day? Calculator by AgeCalculate your daily calcium requirement by age, sex, and pregnancy status. NIH/IOM RDA: 1,000–1,300 mg/day. Includes food sources table and personalized recommendation.How much iron do I need per day? RDA by sex and life stage8 mg/day · Women 19–50: 18 mg/day · Pregnancy: 27 mg/day (IOM/NIH). Enter your daily dietary iron to see if you meet your RDA. Free iron intake calculator.How Much Zinc Per Day? Dosage by Sex and Health GoalHow much zinc per day? Men 11 mg, women 8 mg (NIH RDA); 15 mg for immunity, up to 50 mg to shorten a cold (5–7 days), 12 mg in pregnancy. Full reference table with the 40 mg/day safe upper limit.

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Magnesium is involved in over 300 enzymatic reactions — from protein synthesis to muscle contraction to blood glucose control — yet surveys consistently find that roughly half of US adults consume less than their recommended daily intake. This calculator uses the NIH Office of Dietary Supplements Dietary Reference Intakes (DRI) to return your personal magnesium RDA based on age and sex, recommend the most bioavailable supplement form, and list the best whole-food sources to close the gap.

When to use this calculator

An adult starting a magnesium supplement who wants to confirm the right dose before buying
A pregnant woman checking whether her prenatal vitamin covers her increased magnesium requirement
An athlete or heavy exerciser wanting to know if stress-induced magnesium losses warrant supplementation
A dietitian or nutritionist quickly cross-checking a client's target intake against NIH DRI values

Magnesium RDA by Age & Sex (NIH DRI) + Supplement UL

Age Group	Male (mg/day)	Female (mg/day)	Pregnancy (mg/day)
9–13 years	240	240	—
14–18 years	410	360	400
19–30 years	400	310	350
31–50 years	420	320	360
51+ years	420	320	—
Supplement UL (adults)	350	350	350

Fuente: NIH Office of Dietary Supplements — Magnesium Fact Sheet for Health Professionals (2022). UL applies only to magnesium from supplements/medications, not from food.

How it works

How it's calculated

The calculator looks up the Dietary Reference Intake (DRI) — specifically the Recommended Dietary Allowance (RDA) — published by the NIH Office of Dietary Supplements (last revised 2022).

The RDA represents the average daily intake sufficient to meet the nutrient requirement of 97–98% of healthy individuals in a given age/sex group.

NIH magnesium RDA table by age group

Age group	Male (mg/day)	Female (mg/day)
9–13 years	240	240
14–18 years	410	360
19–30 years	400	310
31–50 years	420	320
51+ years	420	320
Pregnancy (≤18 years)	—	400
Pregnancy (19–30 years)	—	350
Pregnancy (31–50 years)	—	360
Breastfeeding	—	310–360

Note: Pregnant women need 350–400 mg/day and breastfeeding women 310–360 mg/day — the calculator uses the base female values; discuss your prenatal needs with your doctor.

Supplement form and bioavailability

Not all magnesium supplements are equal. Organic salts (glycinate, citrate, malate) are more soluble in intestinal fluid and have consistently higher bioavailability than inorganic forms:

Magnesium glycinate — highest absorption, well tolerated, minimal laxative effect. Preferred for sleep, anxiety, and muscle recovery.

Magnesium citrate — good absorption, mildly laxative at higher doses. Common in constipation relief products.

Magnesium oxide — low absorption (~4%), but common because it is inexpensive and delivers a high elemental-magnesium number on the label. Not recommended if absorption is the goal.

Magnesium malate — good absorption, often marketed for energy and fibromyalgia.

Tolerable Upper Intake Level (UL)

The NIH sets the UL for supplemental magnesium at 350 mg/day for adults. This limit applies only to magnesium from supplements and medications — not from food — because food magnesium is absorbed more gradually. Exceeding the supplement UL typically causes osmotic diarrhea rather than serious toxicity, but very high intakes can cause nausea, cramping, and in rare cases (with impaired kidneys) hypermagnesemia.

Why magnesium matters

Magnesium acts as a cofactor in over 300 enzyme systems. Key functions include:

Energy production: required by ATP synthase; every ATP molecule must be bound to a magnesium ion to be biologically active.

Protein synthesis: needed at ribosomal level.

Blood glucose regulation: cofactor for insulin receptor signaling.

Bone health: ~60% of body magnesium is stored in bone; deficiency is linked to lower bone mineral density.

Cardiovascular function: regulates vascular smooth muscle tone and cardiac rhythm.

Nervous system: modulates NMDA receptors, which explains the link to sleep quality, migraine prevention, and anxiety.

Common deficiency signs

Mild deficiency is often silent. As depletion deepens, symptoms may include:

Muscle twitches, cramps, or restless legs

Fatigue and general weakness

Difficulty falling or staying asleep

Heart palpitations or irregular heartbeat

Migraines or frequent tension headaches

Numbness or tingling in extremities

Elevated blood pressure

Note: these symptoms are non-specific. Low serum magnesium (hypomagnesemia, typically <0.75 mmol/L) requires a blood test to confirm.

Final notes

This calculator provides a general dietary reference value, not a clinical prescription. Individual requirements vary based on absorption capacity, kidney function, medication use, digestive conditions (Crohn's, celiac), and lifestyle factors like chronic stress or heavy alcohol use. Consult a doctor or registered dietitian for personalised advice.

Example: 28-year-old woman

Age: 28 → falls in the 19–30 bracket for females

NIH RDA for females 19–30: 310 mg/day

Supplement form with highest bioavailability: magnesium glycinate or citrate

Best foods: 1 oz pumpkin seeds (156 mg) + 1 cup cooked spinach (78 mg) = already 234 mg from two servings

RDA = 310 mg/day. The gap between a typical Western diet (~228 mg/day median) and this target is roughly 80 mg — easily covered by one 100 mg glycinate capsule plus a daily handful of almonds.

Disclaimer: Los resultados son orientativos y no reemplazan la consulta médica profesional. Antes de tomar decisiones con impacto, consultá con un médico, nutricionista o profesional de la salud matriculado.

Frequently asked questions

How much magnesium do I need per day by age and sex?

Per the NIH Office of Dietary Supplements: men ages 19–30 need 400 mg/day; men 31+ need 420 mg/day. Women 19–30 need 310 mg/day; women 31+ need 320 mg/day. Adolescents (14–18) need 360 mg (female) or 410 mg (male). Pregnant women need 350–400 mg depending on age, and breastfeeding women need 310–360 mg.

What are the early signs and symptoms of magnesium deficiency?

Early symptoms include muscle cramps or twitches (especially at night), unexplained fatigue, difficulty sleeping, and frequent headaches. As deficiency progresses, you may notice heart palpitations, numbness or tingling, and irritability. Many people are mildly deficient without obvious symptoms — serum magnesium below 0.75 mmol/L (1.7 mg/dL) on a blood test is the only way to confirm.

Which form of magnesium supplement is best absorbed?

Magnesium glycinate and magnesium citrate have the best bioavailability in clinical studies — both are organic salts that dissolve well in intestinal fluid. Magnesium oxide, the most common cheap supplement, has only about 4% absorption and is not recommended if your goal is correcting a deficiency. Glycinate is preferred for sleep and anxiety; citrate works well for constipation-prone individuals.

What is the maximum safe dose of magnesium from supplements?

The NIH Tolerable Upper Intake Level (UL) for supplemental magnesium is 350 mg/day for adults. This ceiling applies only to magnesium from supplements and medications — not from food — because the intestine gradually regulates absorption from food. Exceeding the supplement UL usually causes osmotic diarrhea rather than serious harm in healthy adults; people with kidney disease should never supplement without medical supervision.

What foods are highest in magnesium?

Best food sources: pumpkin seeds (1 oz = 156 mg), almonds (1 oz = 80 mg), cooked spinach (1 cup = 78 mg), black beans (½ cup = 60 mg), edamame (½ cup = 50 mg), dark chocolate 70%+ (1 oz = 50 mg), avocado (one medium = 44 mg), banana (one medium = 32 mg). Combining two or three of these daily typically covers the typical dietary gap for most adults.

Does magnesium help with sleep, cramps, and migraines?

Evidence suggests yes, especially for people with low magnesium levels. Muscle cramps usually improve within 5–14 days of supplementation with glycinate. For sleep, improvement may appear in 1–2 weeks. For migraines, the American Headache Society recommends 400–600 mg/day as level B prevention (discuss prophylactic doses with your neurologist, as these exceed the supplement UL). Benefit is greatest in people who actually have a deficiency.

Does magnesium interact with medications?

Yes. Magnesium can reduce absorption of fluoroquinolone and tetracycline antibiotics (separate by 2–4 hours), bisphosphonates for osteoporosis (separate by 2 hours), and levothyroxine. It can also enhance the effect of blood pressure medications. Proton pump inhibitors (PPIs like omeprazole), loop and thiazide diuretics, and certain chemotherapy drugs may lower magnesium levels. Always tell your pharmacist about any supplement you take.

Why do athletes and people under chronic stress need more magnesium?

Strenuous exercise increases urinary and sweat magnesium losses. Psychological stress activates the HPA axis, raising cortisol; cortisol in turn increases urinary magnesium excretion. Both mechanisms can deplete magnesium faster than a typical diet replenishes it — contributing to muscle cramps, poor recovery, and disrupted sleep, all common athlete complaints.

What medications most commonly cause magnesium deficiency?

Proton pump inhibitors (omeprazole, pantoprazole, lansoprazole) used for more than 1 year are the most common pharmaceutical cause — the FDA issued a warning in 2011. Others include loop diuretics (furosemide), thiazide diuretics (hydrochlorothiazide), aminoglycosides, amphotericin B, cisplatin, and cyclosporine. If you take any of these long-term, ask your doctor to check serum magnesium at least once a year.

How is magnesium deficiency diagnosed?

Serum magnesium is the standard lab test: normal range is approximately 0.75–0.95 mmol/L (1.7–2.2 mg/dL). However, serum levels reflect only ~1% of total body magnesium (most is in bone and cells), so serum can appear normal even with intracellular depletion. A 24-hour urinary magnesium test or an RBC (red blood cell) magnesium test can provide a more accurate picture of whole-body status.

Sources & references

Methodology & trust

Editorial

Calculadora de salud revisada por el equipo editorial de Hacé Cuentas, contrastada con NIH Office of Dietary Supplements — Magnesium Fact Sheet for Health Professionals, según nuestra política editorial y metodología.

Updates

Última revisión: June 20, 2026. Los parámetros se verifican periódicamente con las fuentes citadas.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). Magnesium Dosage Calculator: Daily RDA by Age and Sex. Hacé Cuentas. https://hacecuentas.com/magnesio-dosis-deficiencia-sintomas

Contenido bajo licencia CC-BY 4.0 — reutilizable citando la fuente con enlace a Hacé Cuentas.

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