Oxide is 60.3% magnesium by weight and glycinate 11.8–14.1%, so one price list across forms always puts oxide first; this page ranks supplements inside each form instead. It draws on 716 labels from 273 brands in the NIH Dietary Supplement Label Database (DSLD) snapshot of 2026-08-10 and on Amazon prices observed 2026-10-26 to 2026-11-02.
Lowest price per 100 mg of magnesium inside each form: oxide — Nutricost Magnesium Oxide, $0.0148 per 100 mg; citrate — Best Naturals Magnesium Citrate 200 mg, $0.0344 per 100 mg; glycinate — Amazon Elements Chelated Magnesium 270 mg, $0.0666 per 100 mg; malate — Seeking Health Magnesium Malate 500 mg, $0.0460 per 100 mg; taurate — KAL Magnesium Taurate +, $0.1033 per 100 mg. The table below adds the cheapest single-salt label and the fewest capsules for 400 mg in each form.
Three measures, each named
Each form below gets 3 winners, each best by one named measure (price per 100 mg of magnesium, single-salt wording, capsules for 400 mg), computed from labels filed by 2026-08-10 and prices observed 2026-10-26 to 2026-11-02.
- Lowest price per 100 mg of magnesium. Offer price divided by the declared magnesium in the pack, among ranked offers: Amazon listings whose brand, salt, form, dose and pack match the DSLD label.
- Lowest price, single-salt label. The same ranking, limited to labels that name the form as their only magnesium source, with no oxide, "buffered", "complex" or "blend" wording in the DSLD record.
- Fewest capsules for 400 mg. Single-salt hard-capsule labels, ordered by the capsules needed to reach 400 mg of magnesium, kept only when the declared magnesium fits the capsule at a powder density of 0.8 g/mL.
400 mg is a fixed yardstick for comparing labels, not a serving. The Daily Value used on US labels is 420 mg (21 CFR 101.9).
Winners inside each form
A form gets a ranking page at 3 ranked offers; as of 2026-11-02 the counts are glycinate 17, citrate 12, oxide 5, malate 4 and taurate 4.
- Glycinate. 400 mg of magnesium takes 2,840–3,380 mg of glycinate, 4–5 size 00 capsules of salt alone. Labels naming glycinate as the only magnesium source: 73 of 126. "Buffered" glycinate has an alkaline salt, usually oxide, mixed in. Compare: glycinate vs citrate · glycinate vs oxide
- Citrate. 400 mg takes 2,480–3,540 mg of citrate, 4–5 size 00 capsules; the range spans trimagnesium dicitrate and hydrated forms. Single-salt labels: 135 of 212. Compare: citrate vs oxide · citrate vs malate
- Oxide. 400 mg takes 660 mg of oxide, one size 00 capsule. Oxide tops any cross-form price sort, so it is ranked only against other oxide. Single-salt labels: 61 of 124. Compare: glycinate vs oxide · citrate vs oxide
- Malate. 400 mg takes 2,570–3,170 mg of malate, 4–5 size 00 capsules. "Dimagnesium malate" is a different compound and is not counted as malate. Single-salt labels: 20 of 73. Compare: glycinate vs malate · citrate vs malate
- Taurate. 400 mg takes 4,480 mg of taurate, 7 size 00 capsules. Single-salt labels: 4 of 12. Compare: glycinate vs taurate
Other forms
L-threonate (8.3% magnesium), aspartate (7.5–15.6%), gluconate (5.9%) and chloride (12.0–25.5%) have salt pages listing every label; ranked offers as of 2026-11-02 are threonate 1, aspartate 0, gluconate 1 and chloride 0.
- Salt pages: L-threonate · aspartate · gluconate · chloride · all forms
- Compare: glycinate vs threonate · glycinate vs aspartate · glycinate vs gluconate · chloride vs glycinate
What these winners do not mean
The 3 measures above come from label arithmetic and prices observed 2026-10-26 to 2026-11-02; none of them is a lab test or a claim about what magnesium does in the body.
- This site does not test what is inside a capsule. The label audit flags labels whose declared magnesium cannot fit their capsule.
- What published studies measured, salt by salt, is on the absorption page.
- People searching for magnesium for sleep usually compare glycinate and citrate; the labels side by side are in glycinate vs citrate.
- Method: price per 100 mg · price matching · capsule capacity · salt fractions