Same elemental magnesium · two salts · snapshot 2026-08-10
Magnesium carbonate vs chloride: 694–807 vs 783–1,672 mg of compound for 200 mg of magnesium
Magnesium carbonate is 24.8–28.8% elemental magnesium and magnesium chloride is 12.0–25.5%, so 200 mg of magnesium needs 694–807 mg of carbonate against 783–1,672 mg of chloride: 1–2 vs 2–3 size 00 capsules at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. No capsule label names either salt alone as of 2026-08-10, so no capsule verdict is counted. Neither salt has a ranked US retail price as of 2026-11-02.
computed from chemical formulas
Chart data
| Displayed chart text |
|---|
| 100 mg magnesium |
| carbonate 347–404 · chloride 392–836 |
| 200 mg magnesium |
| carbonate 694–807 · chloride 783–1,672 |
| 400 mg magnesium |
| carbonate 1,387–1,614 · chloride 1,567–3,344 |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-11-02 · chemistry 2026-10-17
How much carbonate or chloride carries the same elemental magnesium?
At the same elemental amount, carbonate (24.8–28.8% magnesium) always needs less compound than chloride (12.0–25.5%): for 400 mg of magnesium, 1,387–1,614 mg against 1,567–3,344 mg. That is the mass of powder per dose; how much of it is absorbed is what the studies below measured.
computed| Elemental magnesium | carbonate compound | carbonate size 00 | chloride compound | chloride size 00 |
|---|---|---|---|---|
| 100 mg | 347–404 mg | 1 | 392–836 mg | 1–2 |
| 200 mg | 694–807 mg | 1–2 | 783–1,672 mg | 2–3 |
| 400 mg | 1,387–1,614 mg | 2–3 | 1,567–3,344 mg | 3–5 |
carbonate: anhydrous or hydrated; labels rarely state which; chloride: anhydrous 25.5%, hexahydrate 12.0%; 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
No capsule label names either salt alone as of 2026-08-10, so no capsule verdict is counted. 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 |
|---|---|---|---|---|
| carbonate | 0 | 0 | 0 | 0 |
| chloride | 0 | 0 | 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?
No ranked US retail price is matched for either salt as of 2026-11-02.
computed| Salt | Ranked offers | Lowest per 100 mg | Median per 100 mg | Observed |
|---|---|---|---|---|
| carbonate | 0 | none | none | 2026-11-02 |
| chloride | 0 | none | none | 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 carbonate and chloride side by side?
One study in the PubMed-checked registry measured both salts in the same design; 2 involve carbonate and 3 involve chloride 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 |
| 2022 | Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels. | oxide, citrate, carbonate | 35041150 |
| 2001 | Bioavailability of US commercial magnesium preparations | oxide, chloride, lactate, aspartate | 11794633 |
| 1992 | Blood and urinary magnesium kinetics after oral magnesium supplements. | chloride, gluconate | 1468087 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How many labels name both carbonate and chloride?
No label names both carbonate and chloride as of 2026-08-10, against 23 labels naming carbonate and 19 naming chloride.
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 | carbonate compound | carbonate size 00 | chloride compound | chloride size 00 |
|---|---|---|---|---|
| 25 mg | 87–101 mg | 1 | 98–209 mg | 1 |
| 50 mg | 173–202 mg | 1 | 196–418 mg | 1 |
| 75 mg | 260–303 mg | 1 | 294–627 mg | 1 |
| 100 mg | 347–404 mg | 1 | 392–836 mg | 1–2 |
| 125 mg | 434–504 mg | 1 | 490–1,045 mg | 1–2 |
| 150 mg | 520–605 mg | 1 | 588–1,254 mg | 1–2 |
| 175 mg | 607–706 mg | 1 | 685–1,463 mg | 1–3 |
| 200 mg | 694–807 mg | 1–2 | 783–1,672 mg | 2–3 |
32 additional rows
| Elemental magnesium | carbonate compound | carbonate size 00 | chloride compound | chloride size 00 |
|---|---|---|---|---|
| 225 mg | 780–908 mg | 2 | 881–1,881 mg | 2–3 |
| 250 mg | 867–1,009 mg | 2 | 979–2,090 mg | 2–3 |
| 275 mg | 954–1,110 mg | 2 | 1,077–2,299 mg | 2–4 |
| 300 mg | 1,041–1,211 mg | 2 | 1,175–2,508 mg | 2–4 |
| 325 mg | 1,127–1,312 mg | 2 | 1,273–2,717 mg | 2–4 |
| 350 mg | 1,214–1,412 mg | 2 | 1,371–2,926 mg | 2–5 |
| 375 mg | 1,301–1,513 mg | 2–3 | 1,469–3,135 mg | 3–5 |
| 400 mg | 1,387–1,614 mg | 2–3 | 1,567–3,344 mg | 3–5 |
| 425 mg | 1,474–1,715 mg | 3 | 1,665–3,554 mg | 3–5 |
| 450 mg | 1,561–1,816 mg | 3 | 1,763–3,763 mg | 3–6 |
| 475 mg | 1,648–1,917 mg | 3 | 1,861–3,972 mg | 3–6 |
| 500 mg | 1,734–2,018 mg | 3 | 1,958–4,181 mg | 3–6 |
| 525 mg | 1,821–2,119 mg | 3 | 2,056–4,390 mg | 3–7 |
| 550 mg | 1,908–2,220 mg | 3–4 | 2,154–4,599 mg | 3–7 |
| 575 mg | 1,994–2,320 mg | 3–4 | 2,252–4,808 mg | 4–7 |
| 600 mg | 2,081–2,421 mg | 3–4 | 2,350–5,017 mg | 4–7 |
| 625 mg | 2,168–2,522 mg | 3–4 | 2,448–5,226 mg | 4–8 |
| 650 mg | 2,255–2,623 mg | 4 | 2,546–5,435 mg | 4–8 |
| 675 mg | 2,341–2,724 mg | 4 | 2,644–5,644 mg | 4–8 |
| 700 mg | 2,428–2,825 mg | 4 | 2,742–5,853 mg | 4–9 |
| 725 mg | 2,515–2,926 mg | 4–5 | 2,840–6,062 mg | 4–9 |
| 750 mg | 2,601–3,027 mg | 4–5 | 2,938–6,271 mg | 5–9 |
| 775 mg | 2,688–3,128 mg | 4–5 | 3,036–6,480 mg | 5–9 |
| 800 mg | 2,775–3,228 mg | 4–5 | 3,134–6,689 mg | 5–10 |
| 825 mg | 2,862–3,329 mg | 4–5 | 3,231–6,898 mg | 5–10 |
| 850 mg | 2,948–3,430 mg | 5 | 3,329–7,107 mg | 5–10 |
| 875 mg | 3,035–3,531 mg | 5 | 3,427–7,316 mg | 5–11 |
| 900 mg | 3,122–3,632 mg | 5 | 3,525–7,525 mg | 5–11 |
| 925 mg | 3,208–3,733 mg | 5–6 | 3,623–7,734 mg | 5–11 |
| 950 mg | 3,295–3,834 mg | 5–6 | 3,721–7,943 mg | 6–11 |
| 975 mg | 3,382–3,935 mg | 5–6 | 3,819–8,152 mg | 6–12 |
| 1,000 mg | 3,469–4,036 mg | 5–6 | 3,917–8,361 mg | 6–12 |
Source · Chemical formulas and NIH DSLD labels · snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method