Same elemental magnesium · two salts · snapshot 2026-08-10
Magnesium aspartate vs citrate: 1,279–2,670 vs 1,238–1,770 mg of compound for 200 mg of magnesium
Magnesium aspartate is 7.5–15.6% elemental magnesium and magnesium citrate is 11.3–16.2%, so 200 mg of magnesium needs 1,279–2,670 mg of aspartate against 1,238–1,770 mg of citrate: 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 5 of 62 for citrate. Prices within each salt: no ranked aspartate price; citrate from $0.0344 per 100 mg (median $0.1159, 12 ranked offers); observed 2026-10-26 to 2026-11-02.
computed from chemical formulas
Chart data
| Displayed chart text |
|---|
| 100 mg magnesium |
| citrate 619–885 · aspartate 639–1,335 |
| 200 mg magnesium |
| citrate 1,238–1,770 · aspartate 1,279–2,670 |
| 400 mg magnesium |
| citrate 2,475–3,540 · 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
How much aspartate or citrate carries the same elemental magnesium?
At the same elemental amount, citrate (11.3–16.2% magnesium) always needs less compound than aspartate (7.5–15.6%): for 400 mg of magnesium, 2,475–3,540 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| Elemental magnesium | aspartate compound | aspartate size 00 | citrate compound | citrate size 00 |
|---|---|---|---|---|
| 100 mg | 639–1,335 mg | 1–2 | 619–885 mg | 1–2 |
| 200 mg | 1,279–2,670 mg | 2–4 | 1,238–1,770 mg | 2–3 |
| 400 mg | 2,558–5,340 mg | 4–8 | 2,475–3,540 mg | 4–5 |
aspartate: 1:1 magnesium aspartate 15.64%; bis(hydrogen aspartate) 8.42%, its dihydrate 7.49%; stoichiometry and hydration unresolved; citrate: trimagnesium dicitrate 16.2%; dibasic and hydrated forms as low as 11.3%; 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 5 of 62 for citrate. 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 |
| citrate |
| fits 25 of 62 |
| needs 000 32 of 62 |
| exceeds 5 of 62 |
| Salt | Audited capsule labels | Fits 0 or 00 | Needs 000 | Exceeds 000 |
|---|---|---|---|---|
| aspartate | 15 | 13 | 2 | 0 |
| citrate | 62 | 25 | 32 | 5 |
Source · NIH DSLD labels; mass balance · recognized salt only; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which aspartate and citrate labels are above the assumed size 000 capacity at powder density 0.8 g/mL?
5 of 62 citrate capsule labels declare more magnesium than the named salt alone can deliver from a size 000 capsule, at the most favourable hydration and units per serving; each row opens the label's own arithmetic.
computed with assumption| Label | Salt | Salt per capsule | Verdict |
|---|---|---|---|
| Vitamin World Magnesium Citrate 250 mg | citrate | 1,547 mg | exceeds size 000 |
| Biotech Nutritions Magnesium Citrate | citrate | 1,392 mg | exceeds size 000 |
| Nutricost Magnesium Citrate 420 mg | citrate | 1,300 mg | exceeds size 000 |
| Evlution Nutrition Magnesium Citrate 400 mg | citrate | 1,238 mg | exceeds size 000 |
| NuMedica Magnesium Citrate Extra Strength 200 mg | citrate | 1,238 mg | exceeds size 000 |
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; citrate from $0.0344 per 100 mg (median $0.1159, 12 ranked offers). 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 |
| citrate | 12 | $0.0344 | $0.1159 | 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 citrate side by side?
One study in the PubMed-checked registry measured both salts in the same design; 2 involve aspartate and 10 involve citrate in total. They measured outcomes of the salts, not of any label.
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 |
| 2025 | Comparing the Bioavailability of Two Seawater-Derived Magnesium Preparations. | citrate, hydroxide | 40955524 |
| 2024 | Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPE™ Microcapsules) Versus Other Magnesium Sources. | citrate, glycinate, oxide | 39770988 |
| 2022 | Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels. | oxide, citrate, carbonate | 35041150 |
| 2020 | Dose-Dependent Absorption Profile of Different Magnesium Compounds | oxide, citrate, glycinate, malate | 30761462 |
| 2019 | Timeline (Bioavailability) of Magnesium Compounds in Hours: Which Magnesium Compound Works Best? | sulfate, oxide, taurate, citrate, malate | 29679349 |
| 2012 | Comparison of magnesium status using X-ray dispersion analysis following magnesium oxide and magnesium citrate treatment of healthy subjects | citrate, oxide | 22433473 |
3 additional rows
| Year | Study | Salts measured | PubMed |
|---|---|---|---|
| 2003 | Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study | citrate, oxide, glycinate | 14596323 |
| 1990 | Magnesium bioavailability from magnesium citrate and magnesium oxide | citrate, oxide | 2407766 |
| 1990 | Effect of magnesium citrate and magnesium oxide on the crystallization of calcium salts in urine | citrate, oxide | 2299712 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How many labels name both aspartate and citrate?
11 of 46 labels naming aspartate also name citrate as of 2026-08-10; a named blend does not establish how much magnesium each salt contributes.
measured| Label | Declared elemental per serving | NIH DSLD |
|---|---|---|
| GNC Super Magnesium 400 mg | 400 mg | 224737 |
| Indiana Botanic Gardens Triple Magnesium Advantage | 400 mg | 77282 |
| Metagenics Cal Apatite with Magnesium | 300 mg | 26518 |
| Metagenics Cal Apatite with Magnesium | 300 mg | 26519 |
| New Sun Magnesium Blend | 400 mg | 245303 |
| Perricone MD Nutriceuticals Calcium/Magnesium | 133 mg | 209990 |
| Sundown Naturals Triple Magnesium 500 mg | 500 mg | 56740 |
| Swanson Triple Magnesium Complex 400 mg | 400 mg | 202691 |
3 additional rows
| Label | Declared elemental per serving | NIH DSLD |
|---|---|---|
| Vitamin World Triple Magnesium Complex 400 mg | 400 mg | 62795 |
| Viva Vitamins Super Magnesium 375 mg | 375 mg | 239004 |
| Viva Vitamins Super Magnesium 375 mg | 375 mg | 239006 |
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 | citrate compound | citrate size 00 |
|---|---|---|---|---|
| 25 mg | 160–334 mg | 1 | 155–221 mg | 1 |
| 50 mg | 320–668 mg | 1 | 309–442 mg | 1 |
| 75 mg | 480–1,001 mg | 1–2 | 464–664 mg | 1 |
| 100 mg | 639–1,335 mg | 1–2 | 619–885 mg | 1–2 |
| 125 mg | 799–1,669 mg | 2–3 | 774–1,106 mg | 2 |
| 150 mg | 959–2,003 mg | 2–3 | 928–1,327 mg | 2 |
| 175 mg | 1,119–2,336 mg | 2–4 | 1,083–1,549 mg | 2–3 |
| 200 mg | 1,279–2,670 mg | 2–4 | 1,238–1,770 mg | 2–3 |
32 additional rows
| Elemental magnesium | aspartate compound | aspartate size 00 | citrate compound | citrate size 00 |
|---|---|---|---|---|
| 225 mg | 1,439–3,004 mg | 2–5 | 1,392–1,991 mg | 2–3 |
| 250 mg | 1,598–3,338 mg | 3–5 | 1,547–2,212 mg | 3–4 |
| 275 mg | 1,758–3,672 mg | 3–6 | 1,702–2,434 mg | 3–4 |
| 300 mg | 1,918–4,005 mg | 3–6 | 1,856–2,655 mg | 3–4 |
| 325 mg | 2,078–4,339 mg | 3–6 | 2,011–2,876 mg | 3–4 |
| 350 mg | 2,238–4,673 mg | 4–7 | 2,166–3,097 mg | 3–5 |
| 375 mg | 2,398–5,007 mg | 4–7 | 2,321–3,319 mg | 4–5 |
| 400 mg | 2,558–5,340 mg | 4–8 | 2,475–3,540 mg | 4–5 |
| 425 mg | 2,717–5,674 mg | 4–8 | 2,630–3,761 mg | 4–6 |
| 450 mg | 2,877–6,008 mg | 4–9 | 2,785–3,982 mg | 4–6 |
| 475 mg | 3,037–6,342 mg | 5–9 | 2,939–4,204 mg | 5–6 |
| 500 mg | 3,197–6,676 mg | 5–10 | 3,094–4,425 mg | 5–7 |
| 525 mg | 3,357–7,009 mg | 5–10 | 3,249–4,646 mg | 5–7 |
| 550 mg | 3,517–7,343 mg | 5–11 | 3,403–4,867 mg | 5–7 |
| 575 mg | 3,676–7,677 mg | 6–11 | 3,558–5,088 mg | 5–7 |
| 600 mg | 3,836–8,011 mg | 6–11 | 3,713–5,310 mg | 6–8 |
| 625 mg | 3,996–8,344 mg | 6–12 | 3,868–5,531 mg | 6–8 |
| 650 mg | 4,156–8,678 mg | 6–12 | 4,022–5,752 mg | 6–8 |
| 675 mg | 4,316–9,012 mg | 6–13 | 4,177–5,973 mg | 6–9 |
| 700 mg | 4,476–9,346 mg | 7–13 | 4,332–6,195 mg | 6–9 |
| 725 mg | 4,636–9,680 mg | 7–14 | 4,486–6,416 mg | 7–9 |
| 750 mg | 4,795–10,013 mg | 7–14 | 4,641–6,637 mg | 7–10 |
| 775 mg | 4,955–10,347 mg | 7–15 | 4,796–6,858 mg | 7–10 |
| 800 mg | 5,115–10,681 mg | 8–15 | 4,950–7,080 mg | 7–10 |
| 825 mg | 5,275–11,015 mg | 8–16 | 5,105–7,301 mg | 7–11 |
| 850 mg | 5,435–11,348 mg | 8–16 | 5,260–7,522 mg | 8–11 |
| 875 mg | 5,595–11,682 mg | 8–17 | 5,415–7,743 mg | 8–11 |
| 900 mg | 5,754–12,016 mg | 8–17 | 5,569–7,965 mg | 8–11 |
| 925 mg | 5,914–12,350 mg | 9–17 | 5,724–8,186 mg | 8–12 |
| 950 mg | 6,074–12,684 mg | 9–18 | 5,879–8,407 mg | 9–12 |
| 975 mg | 6,234–13,017 mg | 9–18 | 6,033–8,628 mg | 9–12 |
| 1,000 mg | 6,394–13,351 mg | 9–19 | 6,188–8,850 mg | 9–13 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method