Magnesium labels, decoded.
Read elemental magnesium, check serving sizes and compare cost per 100 mg using worked label examples.
Read the elemental amount
On a U.S. Supplement Facts panel, the magnesium amount refers to elemental magnesium: the magnesium itself, rather than the total weight of a compound such as magnesium citrate. Check the serving size too. The stated amount may cover several capsules.
Sources: NIH · Magnesium fact sheet · NIH · What you need to know about supplements
Put cost beside contents
Divide the bottle price by the number of labelled servings. A hypothetical $24 bottle with 60 servings costs $0.40 per serving, before delivery or discounts. Keep the elemental amount and form beside that price: equal prices per serving do not necessarily mean equal contents.
Sources: NIH · Magnesium fact sheet · NIH · What you need to know about supplements
Keep the question in context
This guide compares labels; it does not determine an appropriate intake. For personal advice about use and possible interactions, speak to a qualified health professional.
Sources: NIH · Magnesium fact sheet · NIH · What you need to know about supplements
Compare the same amount, not just the same price
Using the selected label records: 200 mg across two tablets is 100 mg per tablet; 400 mg across three capsules is about 133.33 mg per capsule. A hypothetical price of 24 for 90 servings of 200 mg is about 0.13 per 100 mg. The same price for 40 servings of 400 mg is 0.15 per 100 mg. This is quantity arithmetic, not evidence of equal absorption or a recommended intake.
Calculate your magnesium comparisonLabel/source checks carried forward from 9 September 2026. Worked examples and navigation added 26 September 2026; this is not a new medical or manufacturer-label review.
Go to the source
Check the original material and the label on the product you are considering.
NIH · Magnesium fact sheetNIH · What you need to know about supplementsThis guide uses published sources. NutraRadar has not conducted product or laboratory testing and has no active affiliate partnerships. Read our disclosure.