Label arithmetic · NIH DSLD 72655
Hard Rhino Magnesium Citrate: 255 mg of magnesium per 1.7 gram, 294 servings
255 mg of magnesium in each 1.7 gram, about 294 servings per 500 Gram. Citrate is 11.3–16.2% magnesium. Inside: salt per scoop, %DV check.
Hard Rhino Magnesium Citrate declares 255 mg of elemental magnesium per serving as citrate, which means 1,578–2,257 mg of magnesium citrate powder in one serving, compared with 1,100 mg in the largest standard capsule; that is the weight of the salt alone, before any fillers or flavours in the scoop. No US retail price matched as of 2026-11-02; 17 of the 135 citrate labels in this registry have a matched price. NIH DSLD 72655, label dated 2017-04-25.
computed from the filed label
Chart data
| Displayed chart text |
|---|
| gluconate |
| 4,352 |
| orotate |
| 3,508 |
| L-threonate |
| 3,091 |
| taurate |
| 2,859 |
| lactate |
| 2,123 |
| glycerophosphate |
| 2,040 |
| glycinate |
| 1,809 |
| malate |
| 1,641 |
| aspartate |
| 1,630 |
| citrate |
| 1,578 |
| sulfate |
| 1,263 |
| chloride |
| 999 |
| carbonate |
| 884 |
| hydroxide |
| 612 |
| oxide |
| 423 |
Data release 2026-08-10-f441aa9f · registry snapshot 2026-08-10 · latest price observation 2026-10-19 · chemistry 2026-10-17
Mass: 1,578–2,257 mg per serving · Price: none matched · % DV: 64% vs 61%
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.
How much citrate powder is in one scoop?
Hard Rhino Magnesium Citrate carries 1,578–2,257 mg of magnesium citrate per serving for 255 mg of elemental magnesium, against 1,100 mg in the largest standard capsule; capsule capacities do not apply to this powder.
computed with assumption| Measure | Value |
|---|---|
| Elemental magnesium per serving | 255 mg |
| Units per serving | Not a discrete unit as of 2026-11-02 |
| Magnesium citrate per serving | 1,578–2,257 mg |
| Magnesium citrate per serving | Not computable as of 2026-11-02 |
| Capsule capacity 0 · 00 · 000 | 545 · 730 · 1,100 mg |
| Verdict | Capsule sizes do not apply |
The filed salt can have more than one hydration state (trimagnesium dicitrate 16.2%; dibasic and hydrated forms as low as 11.3%), so the compound mass is a range.
Source · NIH DSLD 72655 · label 2017-04-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
How much elemental magnesium is actually in this label's filed magnesium lines?
Hard Rhino Magnesium Citrate files 1 magnesium line in NIH DSLD 72655; the selected primary line declares 255 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 |
|---|---|---|
| 255 mg | citrate · Magnesium (Form: as Magnesium Citrate) | Primary serving |
Source · NIH DSLD 72655 · label 2017-04-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Does this label's citrate claim hold up, or could the magnesium come from another source?
The label names one magnesium form, citrate, resolved from the filed magnesium line; capsule capacities do not apply to this form, compared with oxide, the salt richest in magnesium at 60.3%.
computed with assumption| Form named on the label | Elemental fraction | Source |
|---|---|---|
| Magnesium citrate | 11.3–16.2% | filed magnesium line |
Source · NIH DSLD 72655 · label 2017-04-25; 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; 17 of 135 citrate labels have one, against a median of $0.1159 per 100 mg among 12 ranked citrate offers.
computed
Chart data
| Displayed chart text |
|---|
| n=12 |
| P25 $0.0843 |
| P75 $0.1469 |
| median $0.1159 |
| Rank | Label | Per 100 mg | Observed |
|---|---|---|---|
| 1 | Best Naturals Magnesium Citrate 200 mg | $0.0344 | 2026-11-02 |
| 2 | Solgar Magnesium Citrate | $0.0607 | 2026-11-02 |
| 3 | LES Labs Magnesium Citrate | $0.0777 | 2026-11-02 |
| 4 | Bluebonnet Magnesium Citrate | $0.0865 | 2026-11-02 |
| 5 | Solaray Magnesium Citrate 400 mg | $0.0868 | 2026-11-02 |
| Median | 12 ranked citrate offers | $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
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, Hard Rhino Magnesium Citrate lasts 147–294 days: 294 servings against 1–2 servings a day in the filed directions.
computed| Measure | Value |
|---|---|
| Net contents as filed | 500 Gram(s); 1.1 lbs |
| Serving size as filed | 1.7 Gram(s) (~2/3 tsp) |
| Servings per container | 294 |
| Servings per day in the directions | 1–2 |
| Days per bottle | 147–294 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 72655 · label 2017-04-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What does "64% Daily Value" mean here, and does it recompute?
The label declares 64% Daily Value; 255 mg against the 420 mg reference in 21 CFR 101.9 recomputes to 61%, a difference of 3 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 |
| 61 · 64 |
| Declared vs |
| recomputed % DV |
| Group as filed | Declared | Reference | Recomputed |
|---|---|---|---|
| Adults and children 4 or more years of age | 64% | 420 mg | 61% |
Source · NIH DSLD 72655; 21 CFR 101.9 · label 2017-04-25 · 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?
Hard Rhino Magnesium Citrate files 1 other ingredient, and no magnesium stearate, against 43 of 135 citrate labels that list magnesium stearate.
measured| Entry | Filed ingredient or declaration |
|---|---|
| 1 | None |
| Target group | Adult (18 - 50 Years) |
| Target group | Gluten Free |
| Target group | Dairy Free |
Source · NIH DSLD 72655 · label 2017-04-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
What has research measured about citrate, and about side effects?
10 studies in the PubMed-checked registry measured outcomes involving citrate; 1 mention gastrointestinal or adverse outcomes. They measured the salt, not this label.
measured| Year | Study | PubMed |
|---|---|---|
| 2025 | Comparing the Bioavailability of Two Seawater-Derived Magnesium Preparations. | 40955524 |
| 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?
Hard Rhino has 0 FDA recall records matched by brand name in the enforcement data queried 2026-10-19. Hard Rhino 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 |
|---|---|---|---|
| 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 72655 · label 2017-04-25; snapshot 2026-08-10 · release 2026-08-10-f441aa9f · CSV · method
Which labels are closest to this one, with the same salt and dose?
No other label files the same resolved salt within ±10% of this label's dose per unit as of 2026-11-02.
computed| Label | Elemental per unit | Price | Verdict |
|---|---|---|---|
| No neighbour as of 2026-11-02 |
Source · NIH DSLD 72655 · label 2017-04-25; 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 72655 (label 2017-04-25, 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 8 18132 92281 3). The CSV carries the values shown here.
measured| Field | As filed |
|---|---|
| NIH DSLD label | NIH DSLD 72655 |
| Label date | 2017-04-25 |
| Date entered into DSLD | 2017-04-25 |
| Barcode (UPC) as filed | 8 18132 92281 3 |
| Manufactured by: | Guardian Wholesale, Phoenix, AZ |
| Claim category as filed | All Other |
| Claim category as filed | Structure/Function |
| Precautions re: All Other | Do not use or consume if pressure seal is broken. |
18 additional rows
| Field | As filed |
|---|---|
| General Statements: All Other Content | Pure powder |
| Seals/Symbols | Lab tested for purity and quality |
| FDA Statement of Identity | Dietary Supplement |
| Suggested/Recommended/Usage/Directions | 1 Carefully measure out suggested serving size using a microscale. 2 Add to preferred beverage. 3 Mix well. 4 Drink within 10-15 minutes. How to use |
| Precautions re: All Other | Do not use or consume if seal is broken. |
| Formulation re: Does NOT Contain | This is a non-GMO ingredient. |
| Seals/Symbols | Packaged in USA |
| Suggested/Recommended/Usage/Directions | Storage: Store in a cool, dry place. Re-seal zipper immediately after use to preserve freshness. |
| Formulation re: Does NOT Contain | No added fillers |
| General Statements: All Other Content | Only pure ingredients |
| Suggested/Recommended/Usage/Directions | Suggested Use: As a dietary supplement, take 1700 mg (scant ~2/3 tsp) mixed with 8-16 ounces of water or suitable beverage. Taken 1-2 times daily with meals or as directed by your qualified health professional. |
| FDA Disclaimer Statement | These statements have not been evaluated by the Food & Drug Administration. This product is not intended to diagnose, treat, cure or prevent any diseases. |
| Precautions re: Children | Warning: Keep out of the reach of children. Do not take this or any other supplement if under the age of 18, pregnant or nursing a baby, or if you have any known or suspected medical conditions and/or taking prescription drug(s) or OTC medication(s). |
| Precautions re: Pregnant or Nursing or Prescription Medications | Do not take this or any other supplement if under the age of 18, pregnant or nursing a baby, or if you have any known or suspected medical conditions and/or taking prescription drug(s) or OTC medication(s). |
| Precautions re: All Other | Always consult with a qualified health physician before taking any new dietary supplement. |
| Formulation re: Does NOT Contain | Allergens: This product contains no soy, dairy, dairy byproducts, eggs, shellfish, wheat, gluten, tree nuts, or sesame seeds. |
| Physical state | Powder |
| Registry snapshot | 2026-08-10 |
Source · NIH DSLD 72655 · label 2017-04-25; 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.