Same elemental magnesium · two salts · snapshot 2026-08-10
Magnesium hydroxide vs l-threonate: 480 vs 2,424 mg of compound for 200 mg of magnesium
Magnesium hydroxide is 41.7% elemental magnesium and magnesium l-threonate is 8.3%, so 200 mg of magnesium needs 480 mg of hydroxide against 2,424 mg of l-threonate: 1 vs 4 size 00 capsules at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. No capsule label names hydroxide alone, against 0 of 6 for l-threonate. Prices within each salt: no ranked hydroxide price; l-threonate $1.1572 per 100 mg (a single ranked offer); observed 2026-10-26 to 2026-11-02.
computed from chemical formulas
Chart data
| Displayed chart text |
|---|
| 100 mg magnesium |
| hydroxide 240 · l-threonate 1,212 |
| 200 mg magnesium |
| hydroxide 480 · l-threonate 2,424 |
| 400 mg magnesium |
| hydroxide 960 · l-threonate 4,848 |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-11-02 · chemistry 2026-10-17
How much hydroxide or l-threonate carries the same elemental magnesium?
At the same elemental amount, hydroxide (41.7% magnesium) always needs less compound than l-threonate (8.3%): for 400 mg of magnesium, 960 mg against 4,848 mg. That is the mass of powder per dose; how much of it is absorbed is what the studies below measured.
computed| Elemental magnesium | hydroxide compound | hydroxide size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 100 mg | 240 mg | 1 | 1,212 mg | 2 |
| 200 mg | 480 mg | 1 | 2,424 mg | 4 |
| 400 mg | 960 mg | 2 | 4,848 mg | 7 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Estimated salt mass versus assumed capsule capacity
No capsule label names hydroxide alone, against 0 of 6 for l-threonate. Verdicts use the most favourable hydration and the most units per serving at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range; the audited registry as a whole has 8 of 137 capsule labels above size 000.
computed with assumption| Salt | Audited capsule labels | Fits 0 or 00 | Needs 000 | Exceeds 000 |
|---|---|---|---|---|
| hydroxide | 0 | 0 | 0 | 0 |
| L-threonate | 6 | 6 | 0 | 0 |
Source · NIH DSLD labels; mass balance · recognized salt only; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does each cost per 100 mg of elemental magnesium, within its own salt?
Compared only with offers of the same salt: no ranked hydroxide price; l-threonate $1.1572 per 100 mg (a single ranked offer). Prices observed 2026-10-26 to 2026-11-02; a ranking exists only inside one salt, because the compound mass per 100 mg of magnesium differs between salts.
computed| Salt | Ranked offers | Lowest per 100 mg | Median per 100 mg | Observed |
|---|---|---|---|---|
| hydroxide | 0 | none | none | 2026-11-02 |
| L-threonate | 1 | $1.1572 | $1.1572 | 2026-11-02 |
Source · Amazon via licensed data provider; NIH DSLD · unique ASIN × date; prices observed 2026-10-26 to 2026-11-02 · release 2026-08-10-f441aa9f · CSV · method
Has any study measured hydroxide and l-threonate side by side?
No study in the PubMed-checked registry measured hydroxide and l-threonate side by side as of 2026-08-10; 1 involve hydroxide and 0 involve l-threonate separately.
measured| Year | Study | Salts measured | PubMed |
|---|---|---|---|
| 2025 | Comparing the Bioavailability of Two Seawater-Derived Magnesium Preparations. | citrate, hydroxide | 40955524 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How many labels name both hydroxide and l-threonate?
No label names both hydroxide and l-threonate as of 2026-08-10, against 10 labels naming hydroxide and 9 naming l-threonate.
measured| Label | Declared elemental per serving | NIH DSLD |
|---|---|---|
| No label as of 2026-08-10 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does every dose from 25 to 1,000 mg of magnesium need in each salt?
The table converts 40 elemental amounts, 25 to 1,000 mg in 25 mg steps, into compound mass and size 00 capsules for both salts, against 730 mg per size 00 capsule at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. The first eight rows are shown; the rest open below.
computed| Elemental magnesium | hydroxide compound | hydroxide size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 25 mg | 60 mg | 1 | 303 mg | 1 |
| 50 mg | 120 mg | 1 | 606 mg | 1 |
| 75 mg | 180 mg | 1 | 909 mg | 2 |
| 100 mg | 240 mg | 1 | 1,212 mg | 2 |
| 125 mg | 300 mg | 1 | 1,515 mg | 3 |
| 150 mg | 360 mg | 1 | 1,818 mg | 3 |
| 175 mg | 420 mg | 1 | 2,121 mg | 3 |
| 200 mg | 480 mg | 1 | 2,424 mg | 4 |
32 additional rows
| Elemental magnesium | hydroxide compound | hydroxide size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 225 mg | 540 mg | 1 | 2,727 mg | 4 |
| 250 mg | 600 mg | 1 | 3,030 mg | 5 |
| 275 mg | 660 mg | 1 | 3,333 mg | 5 |
| 300 mg | 720 mg | 1 | 3,636 mg | 5 |
| 325 mg | 780 mg | 2 | 3,939 mg | 6 |
| 350 mg | 840 mg | 2 | 4,242 mg | 6 |
| 375 mg | 900 mg | 2 | 4,545 mg | 7 |
| 400 mg | 960 mg | 2 | 4,848 mg | 7 |
| 425 mg | 1,020 mg | 2 | 5,152 mg | 8 |
| 450 mg | 1,080 mg | 2 | 5,455 mg | 8 |
| 475 mg | 1,140 mg | 2 | 5,758 mg | 8 |
| 500 mg | 1,200 mg | 2 | 6,061 mg | 9 |
| 525 mg | 1,260 mg | 2 | 6,364 mg | 9 |
| 550 mg | 1,320 mg | 2 | 6,667 mg | 10 |
| 575 mg | 1,380 mg | 2 | 6,970 mg | 10 |
| 600 mg | 1,440 mg | 2 | 7,273 mg | 10 |
| 625 mg | 1,500 mg | 3 | 7,576 mg | 11 |
| 650 mg | 1,560 mg | 3 | 7,879 mg | 11 |
| 675 mg | 1,619 mg | 3 | 8,182 mg | 12 |
| 700 mg | 1,679 mg | 3 | 8,485 mg | 12 |
| 725 mg | 1,739 mg | 3 | 8,788 mg | 13 |
| 750 mg | 1,799 mg | 3 | 9,091 mg | 13 |
| 775 mg | 1,859 mg | 3 | 9,394 mg | 13 |
| 800 mg | 1,919 mg | 3 | 9,697 mg | 14 |
| 825 mg | 1,979 mg | 3 | 10,000 mg | 14 |
| 850 mg | 2,039 mg | 3 | 10,303 mg | 15 |
| 875 mg | 2,099 mg | 3 | 10,606 mg | 15 |
| 900 mg | 2,159 mg | 3 | 10,909 mg | 15 |
| 925 mg | 2,219 mg | 4 | 11,212 mg | 16 |
| 950 mg | 2,279 mg | 4 | 11,515 mg | 16 |
| 975 mg | 2,339 mg | 4 | 11,818 mg | 17 |
| 1,000 mg | 2,399 mg | 4 | 12,121 mg | 17 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method