Same elemental magnesium · two salts · snapshot 2026-08-10
Magnesium aspartate vs l-threonate: 1,279–2,670 vs 2,424 mg of compound for 200 mg of magnesium
Magnesium aspartate is 7.5–15.6% elemental magnesium and magnesium l-threonate is 8.3%, so 200 mg of magnesium needs 1,279–2,670 mg of aspartate against 2,424 mg of l-threonate: 2–4 vs 4 size 00 capsules at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. 0 of 15 capsule labels naming aspartate alone are above the assumed size 000 capacity at powder density 0.8 g/mL, against 0 of 6 for l-threonate. Prices within each salt: no ranked aspartate 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 |
| aspartate 639–1,335 · l-threonate 1,212 |
| 200 mg magnesium |
| aspartate 1,279–2,670 · l-threonate 2,424 |
| 400 mg magnesium |
| aspartate 2,558–5,340 · 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 aspartate or l-threonate carries the same elemental magnesium?
At the same elemental amount, aspartate (7.5–15.6% magnesium) always needs less compound than l-threonate (8.3%): for 400 mg of magnesium, 2,558–5,340 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 | aspartate compound | aspartate size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 100 mg | 639–1,335 mg | 1–2 | 1,212 mg | 2 |
| 200 mg | 1,279–2,670 mg | 2–4 | 2,424 mg | 4 |
| 400 mg | 2,558–5,340 mg | 4–8 | 4,848 mg | 7 |
aspartate: 1:1 magnesium aspartate 15.64%; bis(hydrogen aspartate) 8.42%, its dihydrate 7.49%; stoichiometry and hydration unresolved; hydration ambiguity stays a range.
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
0 of 15 capsule labels naming aspartate alone are above the assumed size 000 capacity at powder density 0.8 g/mL, 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
Chart data
| Displayed chart text |
|---|
| aspartate |
| fits 13 of 15 |
| needs 000 2 of 15 |
| exceeds 0 of 15 |
| l-threonate |
| fits 6 of 6 |
| needs 000 0 of 6 |
| exceeds 0 of 6 |
| Salt | Audited capsule labels | Fits 0 or 00 | Needs 000 | Exceeds 000 |
|---|---|---|---|---|
| aspartate | 15 | 13 | 2 | 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 aspartate 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 |
|---|---|---|---|---|
| aspartate | 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 aspartate and l-threonate side by side?
No study in the PubMed-checked registry measured aspartate and l-threonate side by side as of 2026-08-10; 2 involve aspartate and 0 involve l-threonate separately.
measured| Year | Study | Salts measured | PubMed |
|---|---|---|---|
| 2005 | Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approach | oxide, chloride, sulfate, carbonate, citrate, gluconate, lactate, aspartate, glycinate | 16548135 |
| 2001 | Bioavailability of US commercial magnesium preparations | oxide, chloride, lactate, aspartate | 11794633 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How many labels name both aspartate and l-threonate?
No label names both aspartate and l-threonate as of 2026-08-10, against 46 labels naming aspartate 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 | aspartate compound | aspartate size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 25 mg | 160–334 mg | 1 | 303 mg | 1 |
| 50 mg | 320–668 mg | 1 | 606 mg | 1 |
| 75 mg | 480–1,001 mg | 1–2 | 909 mg | 2 |
| 100 mg | 639–1,335 mg | 1–2 | 1,212 mg | 2 |
| 125 mg | 799–1,669 mg | 2–3 | 1,515 mg | 3 |
| 150 mg | 959–2,003 mg | 2–3 | 1,818 mg | 3 |
| 175 mg | 1,119–2,336 mg | 2–4 | 2,121 mg | 3 |
| 200 mg | 1,279–2,670 mg | 2–4 | 2,424 mg | 4 |
32 additional rows
| Elemental magnesium | aspartate compound | aspartate size 00 | L-threonate compound | L-threonate size 00 |
|---|---|---|---|---|
| 225 mg | 1,439–3,004 mg | 2–5 | 2,727 mg | 4 |
| 250 mg | 1,598–3,338 mg | 3–5 | 3,030 mg | 5 |
| 275 mg | 1,758–3,672 mg | 3–6 | 3,333 mg | 5 |
| 300 mg | 1,918–4,005 mg | 3–6 | 3,636 mg | 5 |
| 325 mg | 2,078–4,339 mg | 3–6 | 3,939 mg | 6 |
| 350 mg | 2,238–4,673 mg | 4–7 | 4,242 mg | 6 |
| 375 mg | 2,398–5,007 mg | 4–7 | 4,545 mg | 7 |
| 400 mg | 2,558–5,340 mg | 4–8 | 4,848 mg | 7 |
| 425 mg | 2,717–5,674 mg | 4–8 | 5,152 mg | 8 |
| 450 mg | 2,877–6,008 mg | 4–9 | 5,455 mg | 8 |
| 475 mg | 3,037–6,342 mg | 5–9 | 5,758 mg | 8 |
| 500 mg | 3,197–6,676 mg | 5–10 | 6,061 mg | 9 |
| 525 mg | 3,357–7,009 mg | 5–10 | 6,364 mg | 9 |
| 550 mg | 3,517–7,343 mg | 5–11 | 6,667 mg | 10 |
| 575 mg | 3,676–7,677 mg | 6–11 | 6,970 mg | 10 |
| 600 mg | 3,836–8,011 mg | 6–11 | 7,273 mg | 10 |
| 625 mg | 3,996–8,344 mg | 6–12 | 7,576 mg | 11 |
| 650 mg | 4,156–8,678 mg | 6–12 | 7,879 mg | 11 |
| 675 mg | 4,316–9,012 mg | 6–13 | 8,182 mg | 12 |
| 700 mg | 4,476–9,346 mg | 7–13 | 8,485 mg | 12 |
| 725 mg | 4,636–9,680 mg | 7–14 | 8,788 mg | 13 |
| 750 mg | 4,795–10,013 mg | 7–14 | 9,091 mg | 13 |
| 775 mg | 4,955–10,347 mg | 7–15 | 9,394 mg | 13 |
| 800 mg | 5,115–10,681 mg | 8–15 | 9,697 mg | 14 |
| 825 mg | 5,275–11,015 mg | 8–16 | 10,000 mg | 14 |
| 850 mg | 5,435–11,348 mg | 8–16 | 10,303 mg | 15 |
| 875 mg | 5,595–11,682 mg | 8–17 | 10,606 mg | 15 |
| 900 mg | 5,754–12,016 mg | 8–17 | 10,909 mg | 15 |
| 925 mg | 5,914–12,350 mg | 9–17 | 11,212 mg | 16 |
| 950 mg | 6,074–12,684 mg | 9–18 | 11,515 mg | 16 |
| 975 mg | 6,234–13,017 mg | 9–18 | 11,818 mg | 17 |
| 1,000 mg | 6,394–13,351 mg | 9–19 | 12,121 mg | 17 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method