Magnesium citrate vs oxide: what is the difference?
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 $0.01 against $0.052 — about 5.1×.
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 per 200 mg | Units per dose | Products | Panel names |
|---|---|---|---|---|
| Citrate | $0.052 | 0.5 | 6 | Magnesium Citrate |
| Oxide | $0.01 | 0.4 | 6 | Magnesium Oxide |
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.
- Servings per container are derived from net weight rather than read off the label, except where a note on the product says otherwise.
- Most source records have not been checked by a person. The ones that have say so.
- Amazon and Walmart are not included, so “cheapest” means cheapest among the retailers we track.
- Prices go stale. Each one shows when it was last checked, and says so when it is older than the retailer allows us to cache it.
Full comparison of every product in this category: Magnesium. How these numbers are made: How we compare.