Label arithmetic · NIH DSLD 224740
GNC Magnesium 500 mg: 500 mg of magnesium per capsule, 1 capsule a day
500 mg of magnesium per capsule, 1 a day. No US price matched (Nov 2). Inside: salt weight, capsule size.
GNC Magnesium 500 mg declares 500 mg of elemental magnesium per serving as oxide, which needs 829 mg of magnesium oxide in each capsule, against 1,100 mg in the largest standard capsule (size 000) at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range: it fits only that size. No US retail price matched as of 2026-11-02; 10 of the 61 oxide labels in this registry have a matched price. NIH DSLD 224740, label dated 2020-06-24.
computed from the filed label
Chart data
| Displayed chart text |
|---|
| 545 mg |
| 730 mg |
| 1,100 mg |
| 829 mg of oxide per capsule |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-10-19 · chemistry 2026-10-17
Mass: 829 mg per capsule · Price: none matched · % DV: 119% vs 119%
Elemental: The magnesium itself; the rest of the compound weight is the partner molecule.
Compound: The whole salt, such as magnesium glycinate, that must physically fit in the capsule.
Size 000: The largest standard capsule, about 1,100 mg of powder at 0.8 g/mL, the top of the usual 0.6–0.8 range; size 00 holds about 730 mg and size 0 about 545 mg.
Recompute with your price
Enter the price you paid; the declared amount and servings of this label are prefilled, so the result is the cost per 100 mg of elemental magnesium for your bottle.
Same-salt comparison appears here.
Will 500 mg of oxide actually fit in one capsule, or do I need more than one?
Estimated salt mass versus assumed capsule capacity: GNC Magnesium 500 mg implies 829 mg of magnesium oxide in each capsule to deliver 500 mg of elemental magnesium, against 1,100 mg in the largest standard capsule (size 000) at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range. Verdict: needs size 000, read at the most favourable hydration and the most units per serving.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 500 mg |
| Units per serving | 1 |
| Magnesium oxide per serving | 829 mg |
| Magnesium oxide per capsule | 829 mg |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Needs size 000 |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
GNC Magnesium 500 mg files 1 magnesium line in NIH DSLD 224740; the selected primary line declares 500 mg of elemental magnesium per serving, against 0 other rows excluded from the primary amount. A salt named under another nutrient does not turn that nutrient's quantity into elemental magnesium.
measured| Filed amount | Salt or note as filed | Role |
|---|---|---|
| 500 mg | oxide · Magnesium (Form: as Magnesium Oxide) | Primary serving |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Does this label's oxide claim hold up, or could the magnesium come from another source?
The label names one magnesium form, oxide, resolved from the filed magnesium line; at that salt the declaration is within the assumed size 000 capacity at powder density 0.8 g/mL, compared with oxide, the salt richest in magnesium at 60.3%.
computed with assumption| Form named on the label | Elemental fraction | Source |
|---|---|---|
| Magnesium oxide | 60.3% | filed magnesium line |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Is this a good price for the elemental magnesium I'm actually getting?
No US retail price is matched to this label as of 2026-11-02; 10 of 61 oxide labels have one, against a median of $0.0293 per 100 mg among 5 ranked oxide offers.
computed
Chart data
| Displayed chart text |
|---|
| n=5 |
| P25 $0.0258 |
| P75 $0.0356 |
| median $0.0293 |
| Rank | Label | Per 100 mg | Observed |
|---|---|---|---|
| 1 | Nutricost Magnesium Oxide | $0.0148 | 2026-11-02 |
| 2 | tnvitamins Magnesium Oxide 420 mg | $0.0258 | 2026-11-02 |
| 3 | Douglas Laboratories Magnesium Oxide | $0.0293 | 2026-11-02 |
| 4 | Wonder Labs Magnesium Oxide 400 | $0.0356 | 2026-11-02 |
| 5 | Carlson Magnesium Gels 400 mg | $0.0636 | 2026-11-02 |
| Median | 5 ranked oxide offers | $0.0293 | 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
How many days will this bottle last at the label's own serving, and what does a day cost?
Days per bottle cannot be computed for GNC Magnesium 500 mg as of 2026-11-02: servings per container are not filed.
computed| Measure | Value |
|---|---|
| Net contents as filed | 120 Capsule(s) |
| Serving size as filed | 1 Capsule(s) |
| Servings per container | Not filed as of 2026-11-02 |
| Servings per day in the directions | 1 |
| Days per bottle | Not computable as of 2026-11-02 |
| $ per 30 days at one label serving a day | No ranked price as of 2026-11-02 |
| $ per 30 days at 420 mg Daily Value | No ranked price as of 2026-11-02 |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "119% Daily Value" mean here, and does it recompute?
The label declares 119% Daily Value; 500 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 119%, the same within one point.
computed| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 119% | 420 mg | 119% |
Source · NIH DSLD 224740; 21 CFR 101.9 · label 2020-06-24 · release 2026-08-10-f441aa9f · CSV · method
Why does this label contain magnesium stearate, what shell is it, and who is it filed for?
GNC Magnesium 500 mg files 4 other ingredients, including magnesium stearate (reference fraction 4.1% magnesium; no quantity filed, so it is not added to the total) and a gelatin shell, against 30 of 61 oxide labels that list magnesium stearate.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | Microcrystalline Cellulose |
| 2 | Gelatin |
| 3 | Stearic Acid |
| 4 | Magnesium Stearate |
| Shell | gelatin |
| Target group | Adult (18 - 50 Years) |
| Target group | Gluten Free |
| Target group | Dairy Free |
1 additional rows
| Entry | Filed ingredient or declaration |
|---|---|
| Target group | Sugar Free |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What has research measured about oxide, and about side effects?
12 studies in the PubMed-checked registry measured outcomes involving oxide; 2 mention gastrointestinal or adverse outcomes. They measured the salt, not this label.
measured| Year | Study | PubMed |
|---|---|---|
| 2026 | Randomized, open-label study of the short-term pharmacokinetics of oral magnesium oxide in healthy volunteers. | 42091979 |
| 2024 | Comparative Clinical Study on Magnesium Absorption and Side Effects After Oral Intake of Microencapsulated Magnesium (MAGSHAPE™ Microcapsules) Versus Other Magnesium Sources. | 39770988 |
| 2022 | Effects of short-term magnesium supplementation on ionized, total magnesium and other relevant electrolytes levels. | 35041150 |
Source · PubMed-checked study registry · registry checked 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Has this brand had FDA recalls or adverse event reports?
GNC has 3 FDA recall records matched by brand name in the enforcement data queried 2026-10-19. GNC has FDA CAERS adverse event reports on record at brand level, as do 143 of 273 brands in this registry; openFDA states that “there is no certainty that the reported event (adverse event) was actually due to the product” and that reports “cannot be used to estimate the incidence of these events.”
measured| Recall | Date | Reason | Status |
|---|---|---|---|
| F-0626-2017 | 2016-12-14 | Undeclared Allergen: Milk. | Terminated |
| F-1734-2022 | 2022-09-21 | The firm was notified by a customer that the bottle contains green and white capsules instead of the usual white round tablets. They contacted their manufacturer to investigate the issue and the manufacture stated that there was a problem at the filling line. Bottles labeled as Vitamin B6 actually contained Pycnogenol. | Terminated |
| F-0928-2025 | 2025-06-11 | Undeclared Fish allergen (parvalbumin). | Terminated |
Source · openFDA enforcement and CAERS · queried 2026-10-19 · release 2026-08-10-f441aa9f · CSV · method
Is this the same formula as another brand's, and how do their prices differ?
No other brand files the same formulation (ingredients, shell, units and rounded amount) as of 2026-11-02.
computed| Label | Brand | Price per 100 mg |
|---|---|---|
| No cross-brand match as of 2026-11-02 |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
6 labels use the same resolved oxide within ±10% of this label's 500 mg per unit, compared side by side on price and capsule verdict.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| Vitamin World High Potency Magnesium 500 mg (DSLD 20543) | 500 mg | No price | Capsule sizes do not apply |
| Rexall Magnesium 500 mg | 500 mg | No price | Capsule sizes do not apply |
| Nature's Bounty Maximum Strength Magnesium 500 mg | 500 mg | No price | Capsule sizes do not apply |
| Sundown Naturals Magnesium 500 mg | 500 mg | No price | Capsule sizes do not apply |
| Vitamin World High Potency Magnesium 500 mg (DSLD 62988) | 500 mg | No price | Capsule sizes do not apply |
| Finest Nutrition Magnesium 500 mg | 500 mg | No price | Capsule sizes do not apply |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Where does this record come from, what is missing, and how do I cite or correct it?
Every value on this page traces to NIH DSLD 224740 (label 2020-06-24, snapshot 2026-08-10) and the chemistry model of 2026-09-13. 2 gaps remain: No US retail price matched as of 2026-11-02 (barcode 0 48107 20578 2); Servings per container are not filed as of 2026-11-02. The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 224740 |
| Label date | 2020-06-24 |
| Date entered into DSLD | 2020-06-24 |
| Barcode (UPC) as filed | 0 48107 20578 2 |
| Label version · Image difference, same product | NIH DSLD 676 |
| Label version · Image difference, same product | NIH DSLD 25657 |
| Label version · Image difference, same product | NIH DSLD 74831 |
| Distributed by | General Nutrition Corporation, Pittsburgh, PA, USA |
13 additional rows
| Field | As filed |
|---|---|
| Claim category as filed | All Other |
| Claim category as filed | Structure/Function |
| Precautions re: Children | Keep out of reach of children. |
| Storage | Store in a cool, dry place. |
| Formulation re: Other | Essential for strong bones & teeth Necessary for muscle & nerve function |
| General Statements: All Other Content | 120-day supply |
| FDA Statement of Identity | Dietary Supplement |
| Suggested/Recommended/Usage/Directions | Directions: As a dietary supplement, take one capsule daily. |
| Formulation re: Other | Potency verified by GNC procedure #4000. Conforms to USP <2091> for weight. Meets USP <2040> disintegration. |
| Formulation re: Does NOT Contain | No sugar, no starch, no artificial colors, no artificial flavors, sodium free, no wheat, gluten free, no corn, no soy, no dairy. GF Gluten free |
| FDA Disclaimer Statement | These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. |
| Physical state | Capsule |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 224740 · label 2020-06-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
6 brand pages linked below contain magnesium labels from the NIH DSLD registry snapshot dated 2026-08-10.