Magnesium citrate vs oxide: what is the difference?
Our pick for each type, capsules and powder ranked separately: Glycinate, capsules: Nature Made High Absorption Magnesium Glycinate 200 mg (60 capsules); Glycinate, powder: Thorne Magnesium Bisglycinate (60 servings); Citrate, capsules: Nature Made High Absorption Magnesium Citrate 250 mg (120 softgels); Citrate, powder: BulkSupplements.com Magnesium Citrate Powder (1 kg) (before delivery); L-Threonate: Momentous Magnesium L-Threonate (90 capsules) (before delivery). Types with no certified product are listed below. Where to buy
On what this site measures, cost per 200 mg of elemental magnesium, and how much you have to swallow to get it, Oxide is the cheaper of the two, at $0.033 against $0.128, about 3.8×.
Capsules here include softgels and tablets. Powders are priced only against other powders, on each type's own page.
The argument usually made between these two forms is about absorption, tolerance and what time of day to take them. Those are claims about physiology. We do not measure any of them, and this page does not settle them. What it can give you is the part that is checkable: what a real dose costs, how many units it takes, and what the panels actually name.
| Form | Cheapest capsule per 200 mg | Units per dose | Single-salt capsules | Panel names |
|---|---|---|---|---|
| Citrate | $0.128 | 2.0 | 9 | Magnesium Citrate |
| Oxide | $0.033 | 0.5 | 8 | Magnesium Oxide |
Where the price actually goes
The oxide panel prints both numbers: 400 mg of magnesium from 714 mg of the compound. So about 56% of what you swallow is magnesium, and the rest is the molecule carrying it.
That is part of the price gap, and that part is arithmetic rather than branding: a dose means buying and swallowing many times more material. It shows up in the units column above as well as the cost one.
What we are not telling you is whether that is worth it. The case made for the more expensive form is that this particular molecule reaches tissue the others reach less well, which, true or not, is a claim about physiology, and we measure prices and labels. A page that priced the compound and then declared the claim overblown would be doing the same thing it criticizes.
Here the cheaper column is the one to be most careful with
Magnesium oxide carries more magnesium per gram than any other common form, which is exactly why it produces the lowest cost per dose on this site and needs the fewest capsules. It is also the form most consistently described as poorly absorbed. Those two facts have the same cause: the compound is mostly magnesium, and it is not very soluble.
We measure the price, not the absorption. So on this page oxide wins the only column we can fill, and that is not a recommendation. If you already know you tolerate oxide and are buying on cost, the number is real. If you are choosing between forms on how well they work, this page cannot answer that and neither can the ranking on any of our category pages.
Check the panel before the argument
Whichever you prefer on absorption grounds, it is worth confirming the product is actually that salt. Several here name a second, cheaper one on their own panel: which magnesium products are one salt and which are blends.
Where to buy: the pick for each type
The pick is the cheapest certified product, at the exact package sold where the certifier names packages, with no adverse finding on record, a price its retailer let us read recently, and no more than a year’s supply at the label’s serving; per delivered dose where the retailer publishes a delivery rate. Where none does, it is the cheapest such product before delivery, and it says how far the order is from free delivery. It is the same pick the category page shows.
How these lines are chosen
Among 19 products and 19 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 8 products and 8 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 9 products and 9 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below.
How these lines are chosen
Among 5 products and 5 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below. No product here publishes a delivery rate below its free-delivery threshold, so the pick is priced before delivery.
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
How these lines are chosen
Among 7 products and 7 retailer listings we track; Amazon and Walmart are not included. A month is thirty doses of the size in the heading, priced the same way as the per-dose figure beside it. “Delivery known” ranks only products whose retailer publishes a delivery rate; a cheaper product with an unpublished rate is on its own line, or in the full list below. No product here publishes a delivery rate below its free-delivery threshold, so the pick is priced before delivery.
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
A pick has to be independently certified, at the exact package sold where the certifier names packages, and carry no recall or failed test. Nothing we track here is yet. Each of these misses at least one bar, and says which:
Full comparison of every product in this category: Magnesium. Every question we answer: the question index.
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.