Magnesium citrate is 11.3–16.2% magnesium by weight and glycinate 11.8–14.1%, so 200 mg of magnesium takes 1,240–1,770 mg of citrate or 1,420–1,690 mg of glycinate. The ranges exist because labels rarely say which citrate or which hydrate is inside. 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.
People searching for magnesium for sleep usually compare these two salts. This page shows what the labels contain and what studies measured. No trial in the site's PubMed-checked registry compared these two salts for sleep; the one sleep trial on bisglycinate is on magnesium glycinate for sleep.
Which to pick for what
At 400 mg of magnesium, both salts need 4–5 size 00 capsules of salt alone at 0.8 g/mL, so capsule count does not separate them; label wording and price inside each salt do.
- Fewest capsules. For 200 mg of magnesium, either salt needs 2–3 size 00 or 2 size 000 capsules. For 400 mg: 2,480–3,540 mg of citrate or 2,840–3,380 mg of glycinate, which is 4–5 size 00 or 3–4 size 000 capsules for either. Counts assume salt alone at 0.8 g/mL, the top of the usual powder density: 730 mg per size 00, 1,100 mg per size 000; fillers add capsules.
- Lowest cost inside each salt. 30 days at 400 mg a day from the cheapest ranked glycinate offer: $7.99. From the cheapest ranked citrate offer: $4.13. At the median ranked offer, glycinate: $22.67; citrate: $13.90. These are two within-salt figures, not a ranking of the salts.
- What studies measured. Four studies in the site's PubMed-checked registry include both salts:
- PMID 14596323 (2003): a randomised, double-blind trial gave 46 adults 300 mg of magnesium a day as an amino-acid chelate, citrate or oxide and compared bioavailability at that equal dose. The chelate arm was a class of compounds, not one defined glycinate.
- PMID 39770988 (2024): 40 women and men took single doses of oxide, citrate, bisglycinate and a microencapsulated magnesium; plasma magnesium was measured at 0, 1, 4 and 6 hours, with gut side effects such as gastric heaviness.
- PMID 30761462 (2020): absorption of oxide, citrate, glycinate and malate was profiled across several doses, so a result at one dose need not hold at another.
- PMID 16548135 (2005): 80 magnesium-depleted rats each received one of ten salts, both of these included, traced with stable isotopes. Rats, and depletion itself raises absorption.
Side by side
For 400 mg of magnesium, glycinate takes 2,840–3,380 mg of compound and citrate 2,480–3,540 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 citrate |
|---|---|---|
| Magnesium by weight | 11.8–14.1% | 11.3–16.2% |
| Compound for 400 mg of magnesium | 2,840–3,380 mg | 2,480–3,540 mg |
| Size 00 capsules for 400 mg (salt alone) | 4–5 | 4–5 |
| Most magnesium one size 000 capsule can hold | 130–155 mg | 124–178 mg |
| Labels in NIH DSLD naming the salt | 126 | 212 |
| Median magnesium per serving on those labels | 238 mg | 235 mg |
| Ranked US price offers | 17 | 12 |
| Lowest price per 100 mg of magnesium, within the salt | $0.0666 | $0.0344 |
Compound masses are rounded to the nearest 10 mg from the formulas Mg(C₂H₄NO₂)₂ and Mg₃(C₆H₅O₇)₂.
What to check on the label
In the DSLD snapshot of 2026-08-10, 73 of 126 glycinate labels and 135 of 212 citrate labels name that salt as the only magnesium source.
- Magnesium or compound? In Supplement Facts, "Magnesium 200 mg (as magnesium bisglycinate)" should state the magnesium itself. A front label reading "Magnesium Glycinate 400 mg" can be the weight of the whole compound: 400 mg of glycinate holds 47–56 mg of magnesium, and 400 mg of citrate holds 45–65 mg.
- "Buffered" glycinate. The word means an alkaline magnesium salt, usually oxide, is mixed in, and the label rarely says how much. This site keeps buffered labels out of single-salt counts.
- Per-capsule ceiling. A glycinate capsule declaring more than 155 mg of magnesium, or a citrate capsule above 178 mg, cannot hold that much of the named salt alone at 0.8 g/mL. The label audit lists labels like that.
- Which citrate. Trimagnesium dicitrate is 16.2% magnesium; dibasic and hydrated citrates go as low as 11.3%. Few labels say which.
Where to go next
The glycinate ranking and the citrate ranking order 17 and 12 ranked offers by price per 100 mg of magnesium, prices observed 2026-10-26 to 2026-11-02.
- Salt pages: magnesium glycinate · magnesium citrate
- Best by price per 100 mg, single-salt label and capsule count, inside each form
- Related: glycinate vs oxide · citrate vs oxide · glycinate vs malate · citrate vs malate
- Method: salt fractions · capsule capacity · price per 100 mg · what studies measured