$29.95 per container, before delivery
$1.39 per 200mg elemental magnesium, before delivery
$7.50 delivery
Price checked Oct 12, 2026.
Buy at Sports Research (direct) →Label, prices & sources →Double Wood Supplements Magnesium L-Threonate, Magtein (120 capsules)
D · None located
Label read Sep 19, 2026. Where the data comes from
Which magnesium brands are third-party tested?
Cost
$1.43
per 200mg elemental magnesium
$30.95
per container · Double Wood Supplements (direct)
$42.99
a month at one dose a day
Amount per serving
144mg elemental magnesium
Upper intake level
Adults, 350mg a day, from supplements and medications; magnesium in food does not count toward it. One serving of this product holds 144mg, less than that level on its own.
An upper intake level is the largest daily intake unlikely to cause harm for most people. It is not a limit on treatment. Higher amounts are sometimes used, but only under the direction and supervision of a health care provider. It is not a recommendation about what to take.
Source: NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals: the upper intake level, read October 8, 2026 · checked Oct 8, 2026
Definition: NIH Office of Dietary Supplements, Dictionary of dietary supplement terms: what an upper intake level is, read October 8, 2026 · checked Oct 8, 2026
Servings per container
30
Units needed per dose
5.56 capsules
Doses per container
21.6
Cost per serving
$1.03
In whole units
6 capsules = 216mg for $1.55
This is the smallest whole number of capsules that holds at least one comparison dose. It is shown as a caveat and is deliberately not used in ranking, because rounding up changes the amount as well as the price.
- One comparison dose is 5.56 capsules, and capsules cannot be split. The smallest whole number that holds at least the 200 mg comparison dose is 6 capsules, which hold 216 mg.
- Elemental magnesium as printed on this package's own Supplement Facts panel image (Servings Per Container: 30 Servings): "Magnesium L-Threonate (Magtein)® 2000mg" and, on the line below, "Providing elemental magnesium 144mg", per 4-capsule serving. Not derived from the compound weight. The panel names one salt and no second salt. The capsule is gelatin, so the product is not vegan.
Delivery
Delivery cost
Free
Qualifies for free delivery (orders over $30.00).
Cost per dose delivered
$1.43
Delivery policy: Double Wood Supplements (direct), Double Wood Supplements (direct) delivery terms, re-read September 26, 2026 · checked Sep 26, 2026
Buying more than one? Calculate the order
Change the quantity to see the actual container subtotal and whether it reaches the recorded free-delivery threshold.
- Container subtotal
- $30.95
- Delivery
- Free
- Order total, before tax
- $30.95
- Per 200mg elemental magnesium, delivery included
- $1.43
30 labeled servings in this order. Comparison doses are a price yardstick, not advice about how much to take.
Unit price checked Oct 16, 2026.
View this package at Double Wood Supplements (direct) →Set the quantity at the retailer; this calculator does not add items to a cart. Uses the recorded unit price with no coupon or quantity discount. Tax is extra. Delivery terms apply to the contiguous US unless the policy says otherwise.
Delivery terms and limits
Free shipping on orders over $30, from the shipping policy page, first read September 1, 2026: "We currently offer the following shipping methods: Free Shipping for orders over $30, Standard Shipping for orders under $30". The page read "Free Shipping for orders over $30" again on September 26, 2026. The standard rate itself is not published, so delivered cost below $30 is Unknown.
Where to buy
Double Wood Supplements (direct) · lowest recorded available price
we earn nothing on this link
checked todayPrice source: Double Wood Supplements, Double Wood Supplements storefront: Magnesium L-Threonate (Magtein) product feed, three variants · checked Sep 19, 2026
$30.95Buy
Ordered by price, lowest first, and labeled so you can see what each link earns us. Commission is never an input to that ordering. If the cheapest retailer pays us nothing, that is still the one we send you to. No link on this page earns us anything; every Buy button is a plain retailer link.
Price history
Latest recorded price: $30.95 at Double Wood Supplements (direct), checked . Unchanged since we started checking on Sep 19 (28 checks).
We check each price about once a day, so this is the range we recorded, not necessarily every price there has been. It says what changed, not why, and nothing about where the price goes next.
Verification, Tier D: Could not locate independent data
We could not locate independent testing or certification for this product. That is a statement about our search, not about the product. These programs certify what a company submits to them, so a product can be absent simply because it was never entered, which is not a finding against it. Which certifier databases we searched, and when, is listed below. Where a program is not listed there, we have not checked it and do not imply anything either way.
- Searched 4 certifier databases and found no listing for this product, and located no published test results. Programs we did not search are named below as not checked.
- The testing claim we recorded for this product, with where it appeared: "Third-Party Tested" (mark printed on the Supplement Facts panel image, naming no program). With no program named there is no listing to open against it, so it does not raise the verification level.
- Checked NSF Certified for Sport database on Sep 18, 2026: not listed.
- Checked USP Verified database on Sep 21, 2026: not listed.
NSF Certified for Sport: checked, not listed
Checked and absent. The full Certified for Sport directory read of Sep 18, 2026 holds no row under Double Wood Supplements, in this category or any other; magnesium rows from other brands are in the same read. Absence from a database is not a failed test.
Source: NSF Certified for Sport, NSF Certified for Sport directory: full read, Double Wood Supplements rows · checked Sep 18, 2026USP Verified: checked, not listed
Checked and absent. USP's own Verified Products directory was read page by page in a browser on Sep 21, 2026: 16 pages, 159 products, 16 brands, captured in this site's directory snapshot. This brand does not appear in the directory or in its brand facet, and no product in it names this brand. USP verifies the products a company submits to it, so this records which products were submitted and nothing else. Absence from a database is not a failed test.
Source: USP, USP Verified Products directory, full read, September 21, 2026 · checked Sep 21, 2026Informed Sport: checked, not listed
Double Wood Supplements does not appear as a brand in LGC's own Informed Sport product list of 496 brands and 1878 product lines, headed "September-2026", read in full on Sep 24, 2026. Absence from a list is not a failed test: Informed Sport certifies the products a company submits, so this records only that none from this brand is in the program's published list on that date.
Source: LGC (Informed Sport), Informed Sport product list, September 2026 PDF, full read, September 24, 2026 · checked Sep 24, 2026Informed Choice: checked, not listed
Double Wood Supplements does not appear as a brand in LGC's own Informed Choice product list of 200 brands and 851 product lines, headed "September-2026", read in full on Sep 24, 2026. Absence from a list is not a failed test: Informed Choice certifies the products a company submits, so this records only that none from this brand is in the program's published list on that date.
Source: LGC (Informed Choice), Informed Choice product list, September 2026 PDF, full read, September 24, 2026 · checked Sep 24, 2026No test reports located for this product.
Not established: Heavy-metal testing, Label-accuracy testing.
Absence of data is not evidence that a product is clean. It means nobody has published a result we could find.
Label
Form
capsule
Serving size
4 capsules
Active ingredient
Magnesium L-Threonate: 144mg as labeled
Elemental magnesium as printed on this package's own Supplement Facts panel image (Servings Per Container: 30 Servings): "Magnesium L-Threonate (Magtein)® 2000mg" and, on the line below, "Providing elemental magnesium 144mg", per 4-capsule serving. Not derived from the compound weight. The panel names one salt and no second salt. The capsule is gelatin, so the product is not vegan.
Vegan
No
Gluten free
Unknown
Allergens
Unknown
Other ingredients
Gelatin (capsule) (capsule), Rice Flour, Vegetable Stearate
Label facts rest on: Double Wood Supplements, Supplement Facts panel and front label: Double Wood Supplements Magnesium L-Threonate (Magtein), 120 capsules · checked Sep 19, 2026
Other tracked packages
Same category and format and, for vitamin D, the same labeled strength. Different recorded ingredient-form lists are kept separate. Ordered by container price before delivery; only fresh recorded prices are shown. Formulas, flavors and allergens may differ: check each label. These are browsing options, not recommended substitutes.
$58.95 per container, before delivery
$1.36 per 200mg elemental magnesium, before delivery
Free delivery
Price checked Oct 12, 2026.
Buy at Sports Research (direct) →Label, prices & sources →Compare every magnesium L-threonate we price, per 200mg elemental magnesium →
What this rests on: prices we last recorded at the retailer named on each product page, which go stale, and each page says when it was checked; the products we track, not every product sold, and Amazon and Walmart are not among the stores; listings and labels read at the source, each linked from the page. Found an error? Tell us. The full method: How we compare.