Magnesium Dosage Calculator
See how your magnesium intake compares to the recommended amount and the safe supplement limit.
This tool was built by Serge (MSc) using established science and government sources. My academic background covers plant biology, environmental biology, and biogeochemistry. My tools are for educational purposes and give practical guidance, not professional advice.
Magnesium has two numbers worth knowing: the recommended daily amount, and the safe upper limit for magnesium from supplements. This tool compares your intake to both. Pick your group, enter what you get from a supplement, and add a rough food figure if you know it. Use elemental magnesium, which you can work out with the Elemental Mineral Calculator.
How this works
The tool adds your supplement and food magnesium, then compares that total to your recommended amount. It also checks your supplement figure on its own against the safe upper limit for supplemental magnesium.
Percentage of recommended = (supplement + food) ÷ recommended amount × 100
The recommended amounts are 400 to 420 mg a day for men and 310 to 320 mg for women, depending on age. The upper limit for magnesium from supplements is 350 mg a day, which applies to supplements only, not to magnesium from food.
Understanding your result
The percentage tells you how close your total intake is to the recommended amount. The separate upper-limit check matters because too much magnesium from supplements, above 350 mg a day, commonly causes diarrhoea and stomach upset in healthy adults. Magnesium from food does not carry this limit, because the body clears the excess. If your supplement figure alone is over 350 mg, the tool flags it.
Important limitations
- The 350 mg upper limit is for supplemental magnesium in healthy adults. People with kidney problems can be at real risk at lower amounts and should speak with a doctor.
- Recommended amounts vary by age, sex, pregnancy, and health. This tool uses the standard adult figures only.
- Use the elemental magnesium amount, not the compound weight, or the result will be too high.
- This is a general comparison to published reference values, not personal medical advice.
Scientific basis
The recommended amounts and the supplemental upper limit come from these sources:
- Magnesium fact sheet, NIH Office of Dietary Supplements
- Magnesium, Harvard T.H. Chan School of Public Health
This calculator is for general education only and is not medical or professional advice. Speak with a qualified professional before making decisions about supplements, especially if you have a health condition or take medication.