Magnesium Dosage by Body Weight Calculator
Find your optimal magnesium supplement dosage. Based on weight, form, and purpose.
Your current body weight
Type of magnesium supplement
Why you're taking magnesium
Your eating pattern
Known kidney issues?
Taking any medications?
How much magnesium should I take per day?
Adult recommended: 310-420mg daily from all sources (diet + supplements). Supplemental: 200-400mg typical. More isn't better - excess causes diarrhea. Target: Men 400mg, Women 310mg total. Diet provides 100-200mg typically. Supplement the gap. Athletes need more (400-500mg). Keto/diets increase need. Split doses - body absorbs 100-150mg at a time best.
Which magnesium form is best?
Best forms: Glycinate (sleep, anxiety, best absorbed), Citrate (general, somewhat laxative), Threonate (brain, newer). Avoid: Oxide (poor absorption). Choice depends on goal: Sleep/anxiety = glycinate; General = citrate; Brain = threonate; Muscle = malate. Combining forms can be beneficial. Note: Citrate causes loose stools for some - this is a feature if constipated.
When should I take magnesium?
Timing depends on form and goal. Glycinate: 30-60 min before bed for sleep. Threonate: Morning + afternoon (crosses blood-brain). Citrate/Malate: With meals (better absorption). Split doses throughout day helps absorption. Taking with food reduces stomach upset. For sleep: Only in evening. Never take at night if it disturbs sleep. Consistency matters more than exact timing.
Can I take too much magnesium?
Yes. Upper limit: 350mg supplement (not total) for adults. Excess causes: Diarrhea, stomach cramps, nausea. Very high: Low blood pressure, irregular heartbeat, possibly fatal in kidney patients. Kidney disease = don't supplement without doctor. Some forms cause diarrhea at lower doses (citrate, oxide). Start low, increase as tolerated. Split doses throughout day.
Does magnesium interact with medications?
Yes, magnesium interacts with: Antibiotics (take 2+ hours apart), Bisphosphones (osteoporosis), Diuretics, Heart medications, Diabetes medications. Always space magnesium 2+ hours from other supplements/medications. Tell your doctor if taking supplements. Magnesium can affect drug absorption. Consult pharmacist if on multiple medications.