How Much Magnesium Should You Take Per Day?
Last updated: August 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
200–400 mg of elemental magnesium daily from supplements, on top of what you eat. The tolerable upper limit for supplemental magnesium is 350 mg for adults — above that, diarrhoea becomes likely. Food magnesium has no upper limit.
Key takeaways
- 200–400 mg elemental daily is the usual supplemental range.
- The 350 mg upper limit applies to supplements only, not food.
- Read the elemental figure — a 500 mg citrate capsule is only about 80 mg magnesium.
Total requirements versus supplemental dose
Recommended total intakes are roughly 310–420 mg daily for adults depending on age and sex, and that includes food. Nuts, seeds, leafy greens, legumes and whole grains are the main sources. A supplement fills a gap; it is not meant to supply the whole requirement, and many people are closer to adequate than the marketing suggests.
The elemental figure trap
This is where most dosing errors happen. Magnesium citrate is around 16% elemental, glycinate around 14%, oxide around 60%, threonate around 8%. A 500 mg magnesium citrate capsule supplies roughly 80 mg of actual magnesium. Labels vary in which figure they show and rarely make it obvious. Look for the words 'elemental magnesium'.
Why the upper limit exists
The 350 mg supplemental limit is set by the point at which osmotic diarrhoea becomes likely, not by toxicity. Food magnesium does not carry the limit because absorption is regulated differently. In reduced kidney function, magnesium can accumulate to genuinely dangerous levels — that group should not supplement without medical advice.
Key ingredients to understand
The ingredients most relevant to this question, with what the evidence actually supports:
- Magnesium — Magnesium is an essential mineral involved in hundreds of body processes, including nerve and muscle function, energy and blood-sugar control.…
- Magnesium Glycinate — Magnesium glycinate (magnesium bound to glycine) is a gentle, well-absorbed form popular for sleep and relaxation, and easier on the stomach…
- Magnesium Citrate — Magnesium citrate is well absorbed and has a notable laxative effect, which makes it a good choice if constipation is part of the picture and a…
- Calcium — Calcium is the main mineral in bones and teeth and is essential for muscle and nerve function. Getting enough matters for bone health, but very…
Frequently asked questions
Should I split the dose?
Above roughly 200 mg elemental, splitting improves both absorption and bowel tolerance.
How do I know if I am deficient?
Serum magnesium is a poor marker because most is intracellular. Symptoms are non-specific. Dietary intake is usually a better guide.
Can I get enough from food?
Most people can. Nuts, seeds, leafy greens, legumes and whole grains are the highest sources.
Related on FactoWiki
- All health answers
- Ingredient evidence guides
- Magnesium — ingredient guide
- Magnesium Glycinate — ingredient guide
- How we review
This article is general information, not medical advice. FactoWiki may earn a commission from links on product review pages (never on comparisons). Always check with a qualified healthcare professional about your own situation.