ElementalDose

Same elemental magnesium · two salts · snapshot 2026-08-10

Magnesium aspartate vs sulfate: 1,279–2,670 vs 991–2,028 mg of compound for 200 mg of magnesium

Magnesium aspartate is 7.5–15.6% elemental magnesium and magnesium sulfate is 9.9–20.2%, so 200 mg of magnesium needs 1,279–2,670 mg of aspartate against 991–2,028 mg of sulfate: 2–4 vs 2–3 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 none for sulfate (no capsule label names it alone). Neither salt has a ranked US retail price as of 2026-11-02.

computed from chemical formulas
aspartate for 200 mg Mg1,279–2,670 mg7.5–15.6% magnesium · 2–4 size 00
sulfate for 200 mg Mg991–2,028 mg9.9–20.2% magnesium · 2–3 size 00
Exceeds size 0000 of 15 · noneaspartate · sulfate capsule labels
Cheapest by declared elemental magnesium, per 100 mg, within each saltaspartate none · sulfate none0 and 0 ranked offers · 2026-11-02
dumbbell · aspartate vs sulfate · compound mass for 100, 200 and 400 mg magnesium, 1,279–2,670 vs 991–2,028 mg at 200 mg · chemistry 2026-08-10
Compound mass for the same elemental magnesium: dark dot sulfate (9.9–20.2%, lower mass bound), grey dot aspartate (7.5–15.6%, upper mass bound); the labels give each salt's full range.
Chart data
Chart labels and values for the main chart
Displayed chart text
100 mg magnesium
sulfate 495–1,014 · aspartate 639–1,335
200 mg magnesium
sulfate 991–2,028 · aspartate 1,279–2,670
400 mg magnesium
sulfate 1,981–4,057 · aspartate 2,558–5,340

Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-11-02 · chemistry 2026-10-17

Elemental: The magnesium itself; the rest of the compound weight is the partner molecule.

Compound: The whole salt that must physically fit in a capsule; a lower magnesium fraction means more compound for the same magnesium.

How much aspartate or sulfate carries the same elemental magnesium?

At the same elemental amount, sulfate (9.9–20.2% magnesium) always needs less compound than aspartate (7.5–15.6%): for 400 mg of magnesium, 1,981–4,057 mg against 2,558–5,340 mg. That is the mass of powder per dose; how much of it is absorbed is what the studies below measured.

computed
Compound mass and size 00 capsules for aspartate and sulfate
Elemental magnesiumaspartate compoundaspartate size 00sulfate compoundsulfate size 00
100 mg639–1,335 mg1–2495–1,014 mg1–2
200 mg1,279–2,670 mg2–4991–2,028 mg2–3
400 mg2,558–5,340 mg4–81,981–4,057 mg3–6

aspartate: 1:1 magnesium aspartate 15.64%; bis(hydrogen aspartate) 8.42%, its dihydrate 7.49%; stoichiometry and hydration unresolved; sulfate: anhydrous 20.2%, heptahydrate 9.9%; 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 none for sulfate (no capsule label names it alone). 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
Capsule verdicts for aspartate and sulfate labels
SaltAudited capsule labelsFits 0 or 00Needs 000Exceeds 000
aspartate151320
sulfate0000

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?

No ranked US retail price is matched for either salt as of 2026-11-02.

computed
Price per 100 mg of declared elemental magnesium, within each salt
SaltRanked offersLowest per 100 mgMedian per 100 mgObserved
aspartate0nonenone2026-11-02
sulfate0nonenone2026-11-02

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 sulfate side by side?

One study in the PubMed-checked registry measured both salts in the same design; 2 involve aspartate and 2 involve sulfate in total. They measured outcomes of the salts, not of any label.

measured
Registry studies involving aspartate or sulfate
YearStudySalts measuredPubMed
2005Study of magnesium bioavailability from ten organic and inorganic Mg salts in Mg-depleted rats using a stable isotope approachoxide, chloride, sulfate, carbonate, citrate, gluconate, lactate, aspartate, glycinate16548135
2001Bioavailability of US commercial magnesium preparationsoxide, chloride, lactate, aspartate11794633
2019Timeline (Bioavailability) of Magnesium Compounds in Hours: Which Magnesium Compound Works Best?sulfate, oxide, taurate, citrate, malate29679349

Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method

How many labels name both aspartate and sulfate?

No label names both aspartate and sulfate as of 2026-08-10, against 46 labels naming aspartate and 4 naming sulfate.

measured
Labels naming both salts
LabelDeclared elemental per servingNIH 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
Compound mass reference, 25 to 1,000 mg of elemental magnesium
Elemental magnesiumaspartate compoundaspartate size 00sulfate compoundsulfate size 00
25 mg160–334 mg1124–254 mg1
50 mg320–668 mg1248–507 mg1
75 mg480–1,001 mg1–2371–761 mg1–2
100 mg639–1,335 mg1–2495–1,014 mg1–2
125 mg799–1,669 mg2–3619–1,268 mg1–2
150 mg959–2,003 mg2–3743–1,521 mg2–3
175 mg1,119–2,336 mg2–4867–1,775 mg2–3
200 mg1,279–2,670 mg2–4991–2,028 mg2–3
32 additional rows
Compound mass reference, 25 to 1,000 mg of elemental magnesium, additional rows
Elemental magnesiumaspartate compoundaspartate size 00sulfate compoundsulfate size 00
225 mg1,439–3,004 mg2–51,114–2,282 mg2–4
250 mg1,598–3,338 mg3–51,238–2,535 mg2–4
275 mg1,758–3,672 mg3–61,362–2,789 mg2–4
300 mg1,918–4,005 mg3–61,486–3,043 mg3–5
325 mg2,078–4,339 mg3–61,610–3,296 mg3–5
350 mg2,238–4,673 mg4–71,734–3,550 mg3–5
375 mg2,398–5,007 mg4–71,857–3,803 mg3–6
400 mg2,558–5,340 mg4–81,981–4,057 mg3–6
425 mg2,717–5,674 mg4–82,105–4,310 mg3–6
450 mg2,877–6,008 mg4–92,229–4,564 mg4–7
475 mg3,037–6,342 mg5–92,353–4,817 mg4–7
500 mg3,197–6,676 mg5–102,476–5,071 mg4–7
525 mg3,357–7,009 mg5–102,600–5,325 mg4–8
550 mg3,517–7,343 mg5–112,724–5,578 mg4–8
575 mg3,676–7,677 mg6–112,848–5,832 mg4–8
600 mg3,836–8,011 mg6–112,972–6,085 mg5–9
625 mg3,996–8,344 mg6–123,096–6,339 mg5–9
650 mg4,156–8,678 mg6–123,219–6,592 mg5–10
675 mg4,316–9,012 mg6–133,343–6,846 mg5–10
700 mg4,476–9,346 mg7–133,467–7,099 mg5–10
725 mg4,636–9,680 mg7–143,591–7,353 mg5–11
750 mg4,795–10,013 mg7–143,715–7,606 mg6–11
775 mg4,955–10,347 mg7–153,839–7,860 mg6–11
800 mg5,115–10,681 mg8–153,962–8,114 mg6–12
825 mg5,275–11,015 mg8–164,086–8,367 mg6–12
850 mg5,435–11,348 mg8–164,210–8,621 mg6–12
875 mg5,595–11,682 mg8–174,334–8,874 mg6–13
900 mg5,754–12,016 mg8–174,458–9,128 mg7–13
925 mg5,914–12,350 mg9–174,581–9,381 mg7–13
950 mg6,074–12,684 mg9–184,705–9,635 mg7–14
975 mg6,234–13,017 mg9–184,829–9,888 mg7–14
1,000 mg6,394–13,351 mg9–194,953–10,142 mg7–14

Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method