Label arithmetic · NIH DSLD 215806
Dr. Clark Store Magnesium 300 mg: 300 mg of magnesium per capsule, 1 capsule a day
300 mg of magnesium per capsule, 1 a day. No US price matched (Nov 2). Inside: salt weight, capsule size.
Dr. Clark Store Magnesium 300 mg declares 300 mg of elemental magnesium per serving as oxide, which needs 497 mg of magnesium oxide in each capsule, against 545 mg in a size 0 capsule at powder density 0.8 g/mL, the top of the usual 0.6–0.8 range: it fits a size 0 capsule, the smallest of the three sizes compared here. 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 215806, label dated 2020-03-24.
computed from the filed label
Chart data
| Displayed chart text |
|---|
| 545 mg |
| 730 mg |
| 1,100 mg |
| 497 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: 497 mg per capsule · Price: none matched · % DV: 75% vs 71%
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 300 mg of oxide actually fit in one capsule, or do I need more than one?
Estimated salt mass versus assumed capsule capacity: Dr. Clark Store Magnesium 300 mg implies 497 mg of magnesium oxide in each capsule to deliver 300 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: fits size 0, read at the most favourable hydration and the most units per serving.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 300 mg |
| Units per serving | 1 |
| Magnesium oxide per serving | 497 mg |
| Magnesium oxide per capsule | 497 mg |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Fits size 0 |
Source · NIH DSLD 215806 · label 2020-03-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
Dr. Clark Store Magnesium 300 mg files 1 magnesium line in NIH DSLD 215806; the selected primary line declares 300 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 |
|---|---|---|
| 300 mg | oxide · Magnesium (Form: from Magnesium Oxide) | Primary serving |
Source · NIH DSLD 215806 · label 2020-03-24; 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 215806 · label 2020-03-24; 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?
At the label's own serving, Dr. Clark Store Magnesium 300 mg lasts 100 days: 100 servings against 1 serving a day in the filed directions.
computed| Measure | Value |
|---|---|
| Net contents as filed | 100 Capsule(s) |
| Serving size as filed | 1 Capsule(s) |
| Servings per container | 100 |
| Servings per day in the directions | 1 |
| Days per bottle | 100 days |
| $ 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 215806 · label 2020-03-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "75% Daily Value" mean here, and does it recompute?
The label declares 75% Daily Value; 300 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 71%, a difference of 4 points. Labels filed under the earlier 400 mg reference, or with a different filing basis, show gaps of this kind.
computed
Chart data
| Displayed chart text |
|---|
| Declared vs recomputed % |
| DV |
| 71 · 75 |
| Declared vs |
| recomputed % DV |
| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 75% | 420 mg | 71% |
Source · NIH DSLD 215806; 21 CFR 101.9 · label 2020-03-24 · release 2026-08-10-f441aa9f · CSV · method
Why does this label contain these other ingredients, what shell is it, and who is it filed for?
Dr. Clark Store Magnesium 300 mg files 1 other ingredient and a gelatin shell, and no magnesium stearate, against 30 of 61 oxide labels that list magnesium stearate.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | Gelatin Capsules |
| Shell | gelatin |
| Target group | Adult (18 - 50 Years) |
Source · NIH DSLD 215806 · label 2020-03-24; 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?
Dr. Clark Store has 0 FDA recall records matched by brand name in the enforcement data queried 2026-10-19. Dr. Clark Store has no FDA CAERS adverse event report on record at brand level as of 2026-10-19 (143 of 273 brands in this registry have at least one CAERS report).
measured| Recall | Date | Reason | Status |
|---|---|---|---|
| No recall record as of 2026-10-19 |
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 215806 · label 2020-03-24; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
3 labels use the same resolved oxide within ±10% of this label's 300 mg per unit, compared side by side on price and capsule verdict.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| Dr. Clark Store Magnesium 300 mg | 300 mg | No price | Fits size 0 |
| Douglas Laboratories Magnesium Oxide (DSLD 232875) | 300 mg | No price | Fits size 0 |
| Douglas Laboratories Magnesium Oxide (DSLD 245309) | 300 mg | $22.00 · 2026-11-02 | Fits size 0 |
Source · NIH DSLD 215806 · label 2020-03-24; 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 215806 (label 2020-03-24, snapshot 2026-08-10) and the chemistry model of 2026-09-13. 1 gap remain: No US retail price matched as of 2026-11-02 (barcode 6 52384 10447 0). The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 215806 |
| Label date | 2020-03-24 |
| Date entered into DSLD | 2020-03-24 |
| Barcode (UPC) as filed | 6 52384 10447 0 |
| Manufacturer | Self Health Resource Center, Chula Vista, CA |
| Claim category as filed | All Other |
| Claim category as filed | Structure/Function |
| Suggested/Recommended/Usage/Directions | Suggested use: Take 1 capsule, or as directed by a healthcare professional. |
15 additional rows
| Field | As filed |
|---|---|
| Formulation re: Does NOT Contain | Our products don't contain flow agents like Magnesium Stearate. Not now, not ever. |
| General Statements: All Other Content | Sku: 10447-100 |
| Seals/Symbols | Made in USA |
| General Statements: All Other Content | Leader in purity Established by Dr. Clark's Family in 1993 |
| Formulation re: Other | Bone & Muscle support |
| FDA Statement of Identity | Dietary Supplement |
| Seals/Symbols | Quality Assured GMP |
| Storage | Store at room temperature. |
| Precautions re: Children | Keep away from children. |
| Precautions re: Pregnant or Nursing or Prescription Medications | Warning: If you are pregnant, nursing or taking any medications, consult your doctor before use. |
| Precautions re: All Other | If any adverse reactions occur, immediately stop using this product and consult your doctor. If seal under cap is damaged or missing, do not use. |
| 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. |
| General Statements: All Other Content | Company does not adopt any Dr. Clark claims. |
| Physical state | Capsule |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 215806 · label 2020-03-24; 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.