Best Magnesium Oxide
The best magnesium oxide we track, ranked by real cost-per-dose — not paid placements. Across 14 tracked options the typical dose runs $0.09 per serving.
Updated August 2026prices checked what’s changed
Ranked across 14 products · prices checked Aug 25, 2026
How we rank
We rank by cost-per-dose — price ÷ servings, normalized to the daily dose (300 mg/day)— so bottle sizes and strengths compare fairly. Prices are scraped at publication and re-checked when the catalog refreshes (see the “Prices checked” stamp above). There is no paid placement and no kickback for ordering. Full methodology · Editorial standards.
That cost-per-dose number is the one most retailers and review sites leave out — they’ll show a sticker price and a serving size, but not what a day actually costs. We compute it for every product so you can compare like for like.
When cheapest ≠ best value
Our cheapest magnesium oxide per dose is an oxide form — cheap and concentrated, but a low-absorption form, so your body takes up relatively little of it. Chelated forms (e.g. glycinate, citrate) are absorbed far better, so compare cost per absorbed unit, not sticker price alone. A bigger bottle isn’t automatically cheaper per dose either — this list already ranks by cost per dose, so a larger count only wins if it truly costs less per serving. Compare Magnesium Oxide forms.
Our data on this: the big bottle saves a median ~86% per serving · the gummy tax (~2× more) · the form premium · the price spread.
Full ranking by cost per dose
Cost-per-serving normalizes price across bottle sizes — a 60-count and a 365-count compare fairly.
See also: Magnesium Oxide basics · all best-value rankings
Read: Magnesium Oxide guides
Related comparisons, stacks & nutrients
Frequently asked
What is the best-value Magnesium Oxide supplement?+
Magnesium Oxide 400mg, 500 Capsules | Elemental Form for Max Concentration… — $0.03 per serving ($15.19 for 500 servings), the lowest cost-per-dose magnesium oxide in our Amazon US catalog as of August 2026.
How much does Magnesium Oxide cost per day?+
The cheapest magnesium oxide we track works out to $0.03 per serving, against a typical $0.09 per serving across 14 products; to reach the commonly-studied 300 mg/day dose the cheapest is $0.02/day. Retailers and review sites list a price and a serving size but rarely divide it out — this is what a day actually costs, as of August 2026.
What is the typical cost per dose for Magnesium Oxide?+
About $0.09 per serving across 14 tracked magnesium oxide products — the cheapest we track is $0.03 per serving, with most falling between $0.05 and $0.16.
What's the cheapest effective Magnesium Oxide?+
To reach the commonly-studied 300 mg/day dose, Magnesium Oxide 400mg, 500 Capsules | Elemental Form for Max… is the best value at $0.02 per day — cheaper than bottles that look low-priced per serving but are underdosed.
Which Magnesium Oxide is the top rated?+
We don't republish marketplace star ratings — they belong to the retailer, they move constantly, and a 4.6 average tells you nothing about what is in the capsule. The two things you can verify are what a dose costs and whether an independent lab checked the label. On this page the best value is Magnesium Oxide 400mg, 500 Capsules | Elemental Form for Max… at $0.03 per serving; no brand here holds a certification we could verify in a public registry.
References & sources
We link primary sources and paraphrase their findings — never copy their text, tables, or images. Cost-per-dose figures are our own first-party catalog data.