Magnesium supplements compared
We compare what each label says: magnesium per serving, form, how big a serving is and how many you get. We have not tested any product, and we do not say how much you should take.
General information only, not medical advice. Ask a doctor or pharmacist before starting magnesium, especially if you are pregnant, take medicines or have a health condition. Medical disclaimer.
Last checked November 10, 2026. How we evaluate · Corrections and updates
What the official figures say
The US Food and Drug Administration publishes one reference figure for each nutrient, the Daily Value (FDA, content current as of March 5, 2024):
- FDA Daily Value for magnesium: 420 mg a day, the figure the %DV on labels is based on.
The FDA describes Daily Values as the recommended amounts of nutrients to consume or not to exceed each day, and the %DV on a Supplement Facts label is based on them. It is one figure for the label, so it does not show differences by age, sex or pregnancy, or an upper limit. The FDA Daily Value table does not give an upper limit, and we state none. The NIH Office of Dietary Supplements publishes a fact sheet on magnesium; we have not read it for this page, and we link it as a place to look for amounts by age, sex and pregnancy and for upper limits. Ask a doctor or pharmacist about medicines and about any serving above the Daily Value. Source: FDA, Daily Value on the Nutrition and Supplement Facts Labels, content current as of March 5, 2024.
How to read a magnesium label
- Magnesium, not the compound. In the table, the Per serving column is the magnesium amount as recorded in the label record, which may differ from the weight of a compound named in the product title. Compare that column.
- Serving size. Check how many capsules, tablets, softgels or scoops make one serving before you compare doses or count servings.
- Form. The label names the form, such as citrate, bisglycinate or L-threonate.
- Percent Daily Value. The %DV on a label compares one serving with the Daily Value above. The records here give it for adults and children 4 or more years of age.
- Other ingredients. Read the "Other ingredients" list for allergens and added ingredients.
- Independent testing. A testing or certification mark on a label is a statement on the label record, and we have not checked any mark with the certifier. The table quotes the marks a record states (Kosher, Halal and GMP statements are not listed). Check each one on the certifier's own site.
- Your total. The amounts on different labels add up across every supplement and multivitamin.
Comparison
Only products whose label data we have read appear here: on the maker's own page, or in the National Institutes of Health's Dietary Supplement Label Database (DSLD), which records labels as submitted. A label can change after it was recorded. Selection is not a sales ranking. We will add Amazon best-seller positions only with a dated source.
| Product | Per serving | % DV on label | Servings | Form | Marks on the label | Label record |
|---|---|---|---|---|---|---|
| Nature Made Magnesium Glycinate 200 mg, 60 capsules | 200 mg magnesium per serving (2 capsules) | 48% | 30 | Magnesium bisglycinate | No testing mark stated in the record | Source |
| NOW Magnesium Citrate 400 mg, 60 veg capsules | 400 mg magnesium per serving (3 capsules) | 95% | 20 | Magnesium citrate | No testing mark stated in the record | Source |
| Thorne Magnesium Bisglycinate, powder 187 g | 200 mg magnesium per serving (3.11 g powder) | 48% | 60 | Magnesium bisglycinate | NSF Certified Sport | Source |
| Sports Research Magnesium L-Threonate 2000 mg, 90 veggie capsules | 144 mg magnesium per serving (3 capsules) | 34% | 30 | Magnesium L-threonate (named in the product name; the DSLD record lists no ingredient form) | Non-GMO Project Verified; Certified Vegan (Vegan.org) | Source |
All 4 products print a %DV, from 34% to 95% of the Daily Value. The Sports Research product name quotes 2,000 mg, while its record lists 144 mg of magnesium per serving. A clinician or pharmacist can answer questions about any supplement serving.
Marks are quoted from each product's label record and have not been checked with the certifier. Kosher, Halal and GMP statements are not listed.
Products are added as their labels are read. Where a maker's site blocks automated reading, we wait until the label is available on the maker's page or in the DSLD instead of copying it from a retailer.
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Questions
Does a higher dose mean a better product?
A higher dose is a larger number on the label, not a measure of quality. We do not rank products by dose.
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