Principles
- The same criteria and weights apply to every brand, including brands we have affiliate relationships with.
- Commissions never add points, and brands can't pay to change a score or placement.
- We separate evidence about the product (what's in the bottle) from evidence about magnesium (human research).
- Missing evidence is labeled unverified. We don't treat it as proof of failure, and we don't assume the best.
- Our current order is a provisional editorial ranking. We will publish numeric scores only once every product's data comes from the same dated snapshot and has reviewer sign-off.
Scoring weights
Each product is scored 0 to 100 in five categories. Total = 0.30 × testing + 0.20 × formulation + 0.25 × price + 0.15 × reviews + 0.10 × brand support.
| Category | Weight | What we look for |
|---|---|---|
| Testing and manufacturing | 30% | NSF or other product certification, or independent lot-level results; identity, elemental content and contaminants; certificate scope. |
| Formulation and labeling | 20% | Elemental dose, glycinate versus mixed chelate or buffered forms, serving size, unnecessary ingredients, safety disclosure. |
| Price and availability | 25% | One-time price per 100 mg of elemental magnesium and per labeled serving; stock and seller on the same date. |
| Customer reviews | 15% | Verified purchasers, count, recency, sampling bias and complaint patterns. We never guess a rating. |
| Brand scope and support | 10% | Customer service, fulfillment, education and return policies. |
Testing evidence tiers
We assign tiers to specific products, not whole brands, and recheck when a product or formula changes. This is a shared standard across our sites, adopted November 10, 2026.
- Tier 1: Publicly verifiable. Current, independently accessible finished-product test results or a relevant third-party certification tied to the product, with clear SKU, lot or validity information. A general facility certificate alone does not qualify.
- Tier 2: Privately verified. Our editors examined authentic product- or lot-specific lab reports that a brand shared privately. A second reviewer confirms the report matches the exact product, formula and time period. Brand assurances alone do not qualify.
- Tier 3: Manufacturer level. Credible GMP or facility information, ingredient testing or documented testing processes, without verified finished-product results for the specific product.
- Tier 4: Unverified. Documentation is missing, too vague, expired or not tied to the product. Missing evidence is not proof of a failed test.
For tier 2, we keep a confidential log of the product, lot, lab, tested analytes, results, dates and reviewer. We disclose the tier publicly without sharing the report.
| Product | What we found | Tier |
|---|---|---|
| Nootropics Depot | Lot-matched certificates of analysis on the product page | Tier 1 |
| Momentous | NSF Certified for Sport, listed in NSF's directory | Tier 1 |
| EO VITA | Lot report reviewed privately by our editors | Tier 2 |
| Thorne | NSF Certified for Sport on this powder | Tier 1 |
| Transparent Labs | Purity and ingredient reports linked on the product page | Tier 1 |
| Pure Encapsulations | Brand quality and allergen statements; no product test results found | Tier 3 |
| NOW Foods | GMP and in-house testing statements; no product test results found | Tier 3 |
| Doctor's Best | Branded Albion ingredient and GMP statements; no product test results found | Tier 3 |
How we calculate cost per 100 mg
Cost per 100 mg = one-time price ÷ total elemental magnesium in the container × 100. Example: NOW Foods' 180-tablet bottle holds 90 servings of 200 mg, or 18,000 mg; at $19.59 that's $0.11 per 100 mg.
We use one-time prices from the brand's site where it shows one, and a single named retailer (Vitacost) where it doesn't. We show subscription prices separately and never compare one brand's sale price with another's list price. Cost per 100 mg is a comparison tool, not a dose recommendation.
How we treat customer reviews
We report the review count and star average exactly as shown on the brand's product page or the retailer we used, with the date. If a page shows a star breakdown but no average, we say so and show how we calculated it. Small samples get little weight.
How we treat dose
We compare elemental magnesium, never compound weight. We flag any label whose maximum daily directions exceed the NIH adult upper limit of 350 mg of supplemental magnesium.
Update schedule
Prices monthly, testing documents quarterly, the science annually, and sooner when a product, regulation or major study changes. Material changes are logged on our corrections page. The facts behind our tables are published as a dataset: JSON and CSV.
What we don't do
We have not lab tested these products ourselves. If we commission a test, we will publish the lab, date, product and lot. We don't make clinical recommendations, and nothing on this site is medical advice.