Label arithmetic · NIH DSLD snapshot 2026-08-10
How much magnesium is in magnesium hydroxide? 41.7% by weight, so 100 mg of magnesium takes 240 mg of hydroxide
41.7% of magnesium hydroxide is magnesium: 100 mg takes 240 mg of salt, 0.3 size 00 capsules. No ranked US price (Nov 2).
Magnesium hydroxide is 41.7% elemental magnesium, so 100 mg of magnesium needs 240 mg of compound, about 0.3 size 00 capsules at 0.8 g/mL powder density. No capsule label names magnesium hydroxide alone as of 2026-08-10, so no capsule verdict is counted. No US retail price is matched as of 2026-11-02.
computed from chemical formula
Chart data
| Displayed chart text |
|---|
| oxide |
| 60.3% |
| hydroxide |
| 41.7% |
| carbonate |
| 24.8–28.8% |
| chloride |
| 12.0–25.5% |
| sulfate |
| 9.9–20.2% |
| citrate |
| 11.3–16.2% |
| aspartate |
| 7.5–15.6% |
| malate |
| 12.6–15.5% |
| glycinate |
| 11.8–14.1% |
| glycerophosphate |
| 12.5% |
| lactate |
| 10.2–12.0% |
| taurate |
| 8.9% |
| L-threonate |
| 8.3% |
| orotate |
| 7.3% |
| gluconate |
| 5.9% |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-11-02 · chemistry 2026-10-17
Recompute for your bottle
Enter your container price, declared elemental amount and servings to calculate a price per 100 mg for this bottle.
Same-salt comparison appears here.
How much elemental magnesium is actually in 100, 200 or 400 mg of hydroxide?
Magnesium hydroxide is 41.7% elemental magnesium by mass (Mg(OH)₂, molar mass 58.32). Magnesium hydroxide has a molar mass of 58.32 against magnesium's 24.305, so 41.7% of its mass is magnesium. Every 100 mg of elemental magnesium from it needs 240 mg of the compound, calculated 2026-10-17.
computedThis defined salt has one calculated elemental fraction from its formula.
Chart data
| Displayed chart text |
|---|
| hydroxide |
| 960 |
| oxide |
| 663 |
| Elemental magnesium | hydroxide required | Size 00 capsules that much powder fills |
|---|---|---|
| 100 mg | 240 mg | 1 size 00 capsules (0.3 capsules' worth of powder) |
| 200 mg | 480 mg | 1 size 00 capsules (0.7 capsules' worth of powder) |
| 400 mg | 960 mg | 2 size 00 capsules (1.3 capsules' worth of powder) |
Source · Chemical formula and atomic masses · Calculated 2026-08-10; powder density 0.8 g/mL, the top of the usual 0.6–0.8 range · release 2026-08-10-f441aa9f · CSV · method
Estimated salt mass versus assumed capsule capacity
No capsule label names magnesium hydroxide alone as of 2026-08-10, so no capsule verdict is counted. The 10 labels naming this form remain in the full registry.
computed with assumptionNo capsule label naming hydroxide alone can be checked against capsule sizes in this snapshot.
| Mass budget verdict | Labels |
|---|---|
| Capsule labels naming this salt alone | None as of 2026-08-10 |
A size 00 capsule holds about 730 mg of powder at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range; a size 000 about 1,100 mg.
Source · NIH DSLD labels; mass balance · Recognized salt only; 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Is a label called hydroxide really hydroxide, or mixed with another salt?
0 of 5 labels naming hydroxide also name another form as of 2026-08-10. The table counts partner names on filed labels; a named blend does not establish the elemental contribution of each salt. Open the full label list to inspect individual records.
measuredA defined molecular formula permits a calculated fraction.
| Other named form | Labels |
|---|---|
| No other named form | 5 labels reviewed |
Source · NIH DSLD magnesium rows · Labels naming this salt; 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
I need 200 mg of actual magnesium. What changes in compound weight and capsules between hydroxide and other forms?
For 200 mg of elemental magnesium, hydroxide needs 480 mg of compound, against oxide at 332 mg. Size 00 holds about 730 mg at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. Each row uses the stated elemental fraction; hydration ambiguity stays a range, and any price comparison remains within a single salt.
computed with assumption| Salt | Elemental fraction | Compound for 200 mg | Size 00 capsules |
|---|---|---|---|
| Magnesium hydroxide | 41.7% | 480 mg | 1 size 00 |
| Magnesium glycinate | 11.8–14.1% | 1,418–1,691 mg | 2–3 size 00 |
| Magnesium citrate | 11.3–16.2% | 1,238–1,770 mg | 2–3 size 00 |
| Magnesium oxide | 60.3% | 332 mg | 1 size 00 |
| Magnesium malate | 12.6–15.5% | 1,287–1,584 mg | 2–3 size 00 |
Source · Chemical formulas and capsule capacity · Calculated 2026-08-10; powder density 0.8 g/mL, the top of the usual 0.6–0.8 range · release 2026-08-10-f441aa9f · CSV · method
What does hydroxide cost per 100 mg of elemental magnesium, and which label is cheapest by declared elemental magnesium?
No ranked price per 100 mg of declared elemental magnesium is available for hydroxide as of 2026-11-02. No observed price is on review. The 5 recognized labels remain visible in the registry even where no US retail price is matched.
computedNo US retail price is matched to this salt as of 2026-11-02.
| Rank | Label | EC100 | Match and observation |
|---|---|---|---|
| No rank | No ranked offer | No EC100 matched | Checked 2026-11-02 |
Source · Amazon via licensed data provider · Unique ASIN and observation date; prices observed 2026-10-26 to 2026-11-02 · release 2026-08-10-f441aa9f · CSV · method
What else is in hydroxide labels, including stearate, shells and fillers?
5 named excipients appear in the top displayed list among 5 labels naming hydroxide as of 2026-08-10. A listed ingredient is a filed name, not a quantified mass; open the underlying label to check context and capsule material.
measured
Chart data
| Displayed chart text |
|---|
| croscarmellose sodium |
| 1 |
| microcrystalline cellulose |
| silicon dioxide |
| stearic acid |
| vegetable stearate |
| microcrystalline |
| cellulose |
| Filed ingredient | Labels |
|---|---|
| croscarmellose sodium | 1 of 5 |
| microcrystalline cellulose | 1 of 5 |
| silicon dioxide | 1 of 5 |
| stearic acid | 1 of 5 |
| vegetable stearate | 1 of 5 |
Source · NIH DSLD full label ingredient fields · Labels naming this salt; 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What did studies measure about absorption and side effects for hydroxide?
1 study in our PubMed checked registry measured outcomes involving hydroxide as of 2026-08-10. The table names each design and measured outcome, against no pooled comparison across different study methods. No study in our registry of 16 measured side effects for hydroxide as of 2026-08-10.
measured1 study in this registry measured outcomes involving hydroxide.
| Year | Study design and measured outcome | PubMed |
|---|---|---|
| 2025 | Double-blind, randomized, three-arm crossover study in 20 healthy young men and women: placebo (maltodextrin), seawater-derived magnesium citrate (Aquamin-Mg, minimum 10% elemental magnesium), and seawater-derived magnesium hydroxide (Aquamin-MgTg, minimum 33% elemental magnesium). Total magnesium doses were standardized to the RDA for elemental magnesium. Incremental 18-hour urinary magnesium excretion as the relative-bioavailability marker; serum magnesium concentration at 1 and 2 hours post-ingestion (colorimetric assay, run in triplicate). | PMID 40955524 |
Source · PubMed checked study registry · Registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels file hydroxide, and how much do they declare per serving?
5 labels name hydroxide; 5 have a computable elemental amount per serving, with median 410 mg, against the full list linked below. The first eight are shown here. Values are filed elemental magnesium, not an assay of the contents, in the NIH DSLD snapshot 2026-08-10.
measured
Chart data
| Displayed chart text |
|---|
| P10 216 mg |
| P50 410 mg |
| P90 414 mg |
| Label | Declared elemental per serving | NIH DSLD |
|---|---|---|
| BulkSupplements.com Magnesium Hydroxide | 410 mg | 310752 |
| BulkSupplements.com Magnesium Hydroxide | 410 mg | 310753 |
| BulkSupplements.com Magnesium Hydroxide | 410 mg | 310754 |
| Douglas Laboratories Malic Acid + Magnesium | 86 mg | 232010 |
| PureBulk.com Magnesium Hydroxide | 417 mg | 23167 |
Source · NIH DSLD on-market labels · Labels naming this salt; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Where do these numbers come from, and how do I cite or correct them?
The 5 recognized hydroxide labels come from the NIH DSLD snapshot 2026-08-10. Chemistry was calculated from molecular formulas on 2026-10-17; observed retail prices are checked 2026-11-02. The linked CSV carries only values displayed on this page. Cite the release and report a claim if a filed label or calculation needs correction.
computed| Layer | Source and date |
|---|---|
| Labels | NIH DSLD snapshot 2026-08-10 |
| Chemistry | Formula calculation 2026-10-17 |
| Retail | Prices observed 2026-10-26 to 2026-11-02 |
Source · NIH DSLD; chemical formulas; Amazon via licensed data provider · Release 2026-08-10-f441aa9f · release 2026-08-10-f441aa9f · CSV · method