Magnesium: which type?
Magnesium is sold as 6 different salts, each in more than one format. They are not interchangeable: each carries a different amount of actual magnesium per gram, and they differ in how well they are absorbed and tolerated. So each type is compared on its own, and every price below is per 200 mg of elemental magnesium, not per capsule and not per bottle.
The choice of type matters more than the choice of brand within it. Comparing capsules with capsules, the spread across types is 41×, against far less within any one of them. Read that as a reason to choose the type deliberately, not as a reason to buy the cheapest one.
Of the 75 products across every type: 10 named at the exact package by a certifier, 10 at another size only, 55 in no database we searched.
The salt that carries the most magnesium per gram of compound, and commonly described as the least well absorbed, which is a claim this site reports rather than measures. Price per dose flatters it, and that is the point of showing it.
The number on the front of a magnesium bottle is usually the weight of the compound, not the magnesium in it, and some products sold as glycinate name magnesium oxide on the panel as well. Priced on what the panel states.
Widely sold and cheap per elemental milligram. Compared on elemental magnesium, not on the weight of the citrate compound.
Compared on elemental magnesium. Labels commonly print the malate compound weight, which is several times the magnesium it carries.
Magnesium bound to taurine. Panels here state the magnesium itself, which is a small fraction of the compound weight the front of the bottle usually names.
The panels here state a compound weight many times the magnesium it carries, which is why it prices high per dose. What that buys is the question the note on it takes up.
What each type's market looks like
Which type suits you is a question about your body, and this site does not answer it. What it can describe is what is actually on sale in each, and what we were able to check, the things you would otherwise have to open thirty product pages to find out.
| Type | Cheapest capsule | Blended | Certified | Units | Brands |
|---|---|---|---|---|---|
| Oxide powder, capsule, tablet, softgel | $0.033 | Unknown | Unknown | 0.5 | 5 |
| Glycinate powder, capsule, softgel, sachet | $0.125 | 5/26 | 6/26 | 1.5 | 11 |
| Citrate powder, capsule, softgel | $0.128 | Unknown | 3/14 | 2.0 | 6 |
| Malate powder, capsule | $0.143 | 4/9 | Unknown | 1.4 | 5 |
| Taurate powder, capsule | $0.406 | Unknown | Unknown | 4.4 | 4 |
| L-Threonate capsule | $1.36 | Unknown | 1/7 | 4.2 | 5 |
Blended counts products whose own Supplement Facts panel names a second salt, usually magnesium oxide, the cheapest source of elemental magnesium. The product title rarely says so. This is the single most useful column here, because it is a difference between what a product is called and what it contains, and you cannot see it from the shelf.
Certified at size counts products with an NSF or USP listing that names the exact package sold. A listing naming a different size is not counted, which is why this number is smaller than the number of products from certified brands.
Cheapest capsule and units per dose are for capsules, softgels and tablets only: a powder is never priced against a capsule here, and each type's own page ranks its powders separately. Units per dose is how many capsules of the cheapest one make one comparison dose. A cheap form that takes four capsules is a different daily proposition from one that takes half of one.
What this table cannot tell you is which form to take. It says nothing about absorption, tolerability or what any form is typically used for, the one absorption claim this site makes is about magnesium oxide, it carries published citations, and it lives on the cheapest-per-dose page.
Questions about magnesium
Cheapest means the cheapest we track, not the cheapest that exists, and a low cost per dose is a statement about price rather than about how well a form is absorbed, which we do not measure. How these numbers are made: How we compare.
What this rests on: prices we last recorded at the retailer named on each product page, which go stale, and each page says when it was checked; the products we track, not every product sold, and Amazon and Walmart are not among the stores; listings and labels read at the source, each linked from the page. Found an error? Tell us. The full method: How we compare.