Magnesium gluconate is 5.9% magnesium by weight and glycinate 11.8–14.1%, so 200 mg of magnesium takes 3,410 mg of gluconate or 1,420–1,690 mg of glycinate. Gluconate carries the smallest magnesium share of the 15 salts in the site's chemistry table. Label counts come from the NIH Dietary Supplement Label Database (DSLD) snapshot of 2026-08-10; prices come from Amazon offers observed 2026-10-26 to 2026-11-02 and are compared only inside one salt.
Which to pick for what
At 400 mg of magnesium, gluconate needs 10 size 00 capsules of salt alone and glycinate 4–5, by the formulas Mg(C₆H₁₁O₇)₂ and Mg(C₂H₄NO₂)₂ at 0.8 g/mL.
- Fewest capsules. For 200 mg of magnesium: 3,410 mg of gluconate, 5 size 00 or 4 size 000 capsules, against 1,420–1,690 mg of glycinate, 2–3 size 00 or 2 size 000. For 400 mg: 6,830 mg of gluconate, 10 size 00 or 7 size 000, against 2,840–3,380 mg of glycinate, 4–5 size 00 or 3–4 size 000. Counts assume salt alone at 0.8 g/mL: 730 mg per size 00, 1,100 mg per size 000.
- What labels declare. Median magnesium per serving on DSLD labels, snapshot 2026-08-10, gluconate: 133 mg; glycinate: 238 mg. The 400 mg figures are a yardstick for comparing salts, not a serving.
- Lowest cost inside each salt. Ranked US price offers as of 2026-11-02, gluconate: 1; glycinate: 17. 30 days at 400 mg a day from the cheapest ranked glycinate offer: $7.99. From the cheapest ranked gluconate offer: $73.97.
- What studies measured. One study in the site's PubMed-checked registry includes both salts, and it was done in rats; as of October 2026 none compared them in people.
- PMID 16548135 (2005): 80 magnesium-depleted rats each received one of ten salts, both of these included, traced with stable isotopes. Depletion itself raises absorption.
- PMID 1468087 (1992): 12 adults with normal blood magnesium spent a week each on a magnesium chloride solution, slow-release chloride tablets and gluconate tablets, 16 mmol (about 389 mg of magnesium) per dose. Urinary, serum and white-cell magnesium were measured over 24 hours.
- For glycinate: PMID 14596323 (2003; 46 adults, 300 mg a day, amino-acid chelate against citrate and oxide) and PMID 39770988 (2024; 40 adults, plasma magnesium over 6 hours after single doses).
Side by side
For 400 mg of magnesium, glycinate takes 2,840–3,380 mg of compound and gluconate 6,830 mg; label counts are from the DSLD snapshot of 2026-08-10 and prices were observed 2026-10-26 to 2026-11-02.
| Measure | Magnesium glycinate | Magnesium gluconate |
|---|---|---|
| Magnesium by weight | 11.8–14.1% | 5.9% |
| Compound for 400 mg of magnesium | 2,840–3,380 mg | 6,830 mg |
| Size 00 capsules for 400 mg (salt alone) | 4–5 | 10 |
| Most magnesium one size 000 capsule can hold | 130–155 mg | 64 mg |
| Labels in NIH DSLD naming the salt | 126 | 20 |
| Median magnesium per serving on those labels | 238 mg | 133 mg |
| Ranked US price offers | 17 | 1 |
| Lowest price per 100 mg of magnesium, within the salt | $0.0666 | $0.6164 |
Compound masses are rounded to the nearest 10 mg.
What to check on the label
In the DSLD snapshot of 2026-08-10, 6 of 20 gluconate labels and 73 of 126 glycinate labels name that salt as the only magnesium source.
- Magnesium or compound? Supplement Facts should state the magnesium itself. As compound weight, "Magnesium Gluconate 500 mg" holds 29 mg of magnesium, and "Magnesium Glycinate 400 mg" holds 47–56 mg.
- Per-capsule ceiling. One size 000 capsule holds at most 64 mg of magnesium as gluconate alone at 0.8 g/mL, and a size 00 about 43 mg. A gluconate capsule declaring more cannot be gluconate alone; the label audit lists labels like that.
- "Buffered" glycinate. The word means an alkaline magnesium salt, usually oxide, is mixed in, and the label rarely says how much. This site keeps such labels out of single-salt counts.
Where to go next
The glycinate ranking orders 17 ranked offers by price per 100 mg of magnesium, prices observed 2026-10-26 to 2026-11-02. Gluconate gets a ranking page once it has 3 ranked offers; it has 1 as of 2026-11-02.