Best magnesium glycinate supplements (2026): Thorne, Momentous, Klean and BulkSupplements by cost per 200 mg

Which magnesium glycinate should you buy?

Choose Momentous Magnesium Bisglycinate if you want capsules with a labeled 200 mg and an NSF Certified for Sport listing. A 60-capsule bottle is $16.99, about $0.57 per 200 mg of magnesium and $206.71 a year at two capsules a day^{4, 5}. NSF lists it for all lots⁶. The catch is that Momentous’s refund policy says delivered products generally can’t be returned⁷.

Choose Thorne Magnesium Bisglycinate if you’d rather drink it or want a return window. A scoop is 200 mg, and a 60-scoop tub is $52, about $0.87 per 200 mg and $316.33 a year¹. NSF lists it with 21 lot numbers³. The catch is that it costs the most of the four, and approved returns carry a 25% restocking fee².

Klean Magnesium is a 120 mg capsule, $26.50 for 90, which works out to about $0.49 per 200 mg^{8, 9}. NSF lists two entries for the 90-capsule product, with 11 and 13 lot numbers^{12, 13}. The catch is that Klean’s directions allow up to four capsules a day, 480 mg, above NIH’s 350 mg limit for magnesium from supplements^{9, 21}. Its page also asks you to log in to add to cart⁸.

BulkSupplements Magnesium Glycinate Powder is far cheaper: $25.97 for a 500 g bag, about $0.08 per 200 mg and about $42 a year at its 300 mg label serving^{16, 17}. The label declares magnesium glycinate and magnesium oxide, not glycinate alone, and doesn’t say how much of the 300 mg is each¹⁷. NSF’s own supplement listing names the powder but shows no lot numbers, date or composition, so it can’t confirm the current glycinate-plus-oxide formula¹⁸. Opened bags get only a partial refund¹⁹.

None of this shows that one works better than another. What differs is the cost per 200 mg, the form on the label, the certifier listing and what happens if you want to send it back. For what trials found on sleep, see magnesium for sleep: what trials show.

Thorne, Momentous, Klean and BulkSupplements side by side

Prices are US one-time prices on each maker’s page, before tax and shipping. All four prices were checked on November 6, 2026. Everything below is a maker’s, certifier’s or regulator’s own statement. None of it is an independent measurement.

These links go to each brand’s own store and earn us no commission.

Which one fits which need

Each suits a different need, and this isn’t a ranking. Start with whether you want a capsule or a powder, then decide how much a certifier listing and a return matter to you.

• You want capsules with a labeled 200 mg and an NSF sport listing: Momentous Magnesium Bisglycinate. It’s $16.99 for 60 capsules, about $0.57 per 200 mg, and NSF lists it for all lots^{5, 6}. The catch: delivered products generally can’t be returned, and the money-back guarantee on its page has no stated terms^{4, 7}.
• You want a drink powder with a short ingredient list, or a way to send it back: Thorne Magnesium Bisglycinate. It’s $52 for 60 scoops, with citric acid and monk fruit concentrate as the only other ingredients, and NSF lists 21 lot numbers^{1, 3}. The catch: about $0.87 per 200 mg, and a 25% restocking fee on approved returns².
• You want to set the dose one capsule at a time, in a capsule NSF lists: Klean Magnesium. It’s $26.50 for 90 capsules of 120 mg, about $0.49 per 200 mg^{8, 9}. The catch: four capsules would be 480 mg, above NIH’s limit, the page asks for a login, and returns carry a 15% fee plus shipping^{8, 9, 11, 21}.
• You want the lowest cost per milligram and can accept a glycinate-plus-oxide label: BulkSupplements Magnesium Glycinate Powder. It’s $25.97 for 500 g, about $0.08 per 200 mg, with no other ingredients^{16, 17}. The catch: NSF’s listing shows no lot numbers or composition, a serving is 300 mg, and opened bags get a partial refund^{18, 19}.
• You’re drug-tested: Thorne, Momentous and Klean are in NSF’s Certified for Sport database, and you can match the lot number on your bottle to the listed lots where lots are listed^{3, 6, 12, 13}.

How cost per 200 mg is worked out

We divided each container’s price by the milligrams of magnesium on its label, then scaled to 200 mg. Each label lists elemental magnesium, the figure NIH uses²¹. Thorne’s and Momentous’s servings are 200 mg, so their numbers are straight from the label^{1, 4}.

Klean’s 120 mg capsule and BulkSupplements’ 300 mg serving don’t divide evenly into 200 mg, so for them it’s arithmetic, not a label dose^{9, 17}. For Klean, 200 mg is 1.67 capsules. In practice two capsules, 240 mg, cost about $0.59 a day, or about $215 a year⁸. The label serving for BulkSupplements is 300 mg, about $42 a year, so scaling down to 200 mg is a way to compare, not how the label tells you to take it^{16, 17}.

Shipping isn’t in these numbers. BulkSupplements’ flat-rate shipping starts at $9.95, and orders over $59 ship free in the contiguous US, so a single $25.97 bag costs at least that much more to ship unless the order is bigger²⁰.

Glycinate, bisglycinate and oxide: what the labels say

Makers use “glycinate” and “bisglycinate” for magnesium bound to the amino acid glycine. Momentous says its bisglycinate is chelated to glycine, and Klean’s data sheet calls its glycinate a chelate^{4, 10}. Thorne’s, Momentous’s and Klean’s labels declare only that one form^{1, 4, 9}. NIH’s fact sheet doesn’t discuss either name²¹.

BulkSupplements is different. Its label declares magnesium glycinate and magnesium oxide, and doesn’t say the split¹⁷. NIH says the aspartate, citrate, lactate and chloride forms tend to be more bioavailable than oxide and sulfate, but it doesn’t discuss glycinate, so it can’t say how this blend compares²¹. If you want a label that declares glycinate or bisglycinate alone, the other three are the ones.

Thorne says its powder is well absorbed, and BulkSupplements calls its powder a gentle and bioavailable form. Neither page cites a study^{1, 15}. Thorne also says some people get gas, bloating or diarrhea, and that it resolves when the amount is reduced¹.

What an NSF listing does and doesn’t tell you

We looked each product up in NSF’s databases instead of relying on a badge on a store page. Thorne has 21 certified lot numbers, Momentous’s entry says lot “All”, and Klean has two entries with 11 and 13^{3, 6, 12, 13}. A bigger number isn’t a better product. It’s how many lots NSF has listed, and you can match the lot number on your bottle to the list.

None of the four listings shows a certification date^{3, 6, 12, 13, 18}. A sport certification is about what’s in the product, not about health effects. Klean’s product page shows no product-specific NSF mark or lot lookup, so NSF’s database is the evidence of its listing^{8, 12}.

BulkSupplements’ listing is a different one: NSF’s dietary supplement listing under NSF/ANSI Standard 173. It names the magnesium glycinate powder as one of 29 products from a Henderson, Nevada facility¹⁸. It shows no lot numbers, so you can’t match a bag to it, and no composition, so it can’t confirm the current glycinate-plus-oxide formula. The listing is under the company name Hard Eight Nutrition LLC dba BulkSupplements.com, and the product page’s text doesn’t mention NSF or third-party testing^{15, 18}. NSF’s Certified for Sport database also lists it, with one lot number for a 1 kg package²⁶. See are supplements third-party tested for both listings.

Makers add their own statements. Thorne says it tests each ingredient for identity, purity and potency and publishes no results¹. Momentous says every batch is third-party tested and NSF Certified for Sport, and its page shows no test results⁴. For how we weigh these, see how we choose third-party tested supplements.

How much magnesium is too much?

NIH sets the upper limit for magnesium from supplements and medicines at 350 mg a day for adults. It doesn’t count food. Higher supplement doses can cause diarrhea, nausea and abdominal cramping, and the risk of toxicity rises when the kidneys clear less magnesium²¹. The limit is 65 mg at ages 1 to 3 and 110 mg at ages 4 to 8, so a 200 mg serving is above it for a young child²¹.

That is why Klean’s four-capsule top dose, 480 mg, stands out, and why BulkSupplements’ 300 mg serving leaves only 50 mg for any other magnesium supplement or medicine^{9, 17, 21}. Thorne’s and Momentous’s 200 mg servings leave 150 mg^{1, 4}.

NIH lists interactions with oral bisphosphonates, tetracycline and quinolone antibiotics, and loop and thiazide diuretics, and says long-term proton pump inhibitor use can lead to low blood magnesium²¹. Momentous tells you to check with your doctor first if you take diuretics, antibiotics or bisphosphonates, Thorne advises pregnant users to consult a practitioner, and Klean’s label says the same if you’re pregnant, lactating, have a health condition or take medication^{1, 4, 9}. Whether and how much to take is a question for your clinician.

Returns and guarantees

Thorne takes return requests within 60 days, but every approved return carries a 25% restocking fee, and the page doesn’t say who pays return shipping². Klean allows 30 days with preauthorization and keeps a 15% processing fee plus shipping. Its policy doesn’t say whether an opened bottle qualifies¹¹.

BulkSupplements gives a full refund within 30 days of the invoice date only if the item is unopened. An opened item gets a partial refund equal to the price of the smallest unit offered for that product, and you pay return postage¹⁹. The smallest powder size on the product page is 100 g at $20.97, but we couldn’t confirm how the rule applies to an opened 500 g bag¹⁶.

Momentous is the outlier. Its refund policy says it generally doesn’t accept returns of delivered products, and the policy doesn’t mention the money-back guarantee on the product page^{4, 7}. If a return matters to you, ask first or choose another.

Does magnesium glycinate help you sleep?

The closest trial, in 155 adults with poor sleep, found a small gap in insomnia scores between 250 mg a day of magnesium bisglycinate and placebo, and the gap only just reached statistical significance²⁵. It used another maker’s capsules, not any product here, so read magnesium for sleep: what trials show before buying for that reason.

BulkSupplements and the FDA record

openFDA’s food enforcement reports list two voluntary Class II recalls by Hard Eight Nutrition, which owns the BulkSupplements.com trademark. Both are marked terminated. One began Aug 6, 2018, over undeclared shellfish in glucosamine sulfate potassium. The other began Jun 25, 2025, over possible Staphylococcus aureus contamination of inositol powder^{15, 22}.

FDA’s Aug 27, 2015 warning letter called the firm’s caffeine powder adulterated, and a Feb 5, 2016 letter says the firm appeared to have addressed the violations^{23, 24}. None of these involves magnesium.

What we couldn’t confirm

Thorne’s own page doesn’t state the tub’s weight (NSF’s listing gives 226.2 g) or where its magnesium comes from, and whether a given tub’s lot is on NSF’s list depends on the lot printed on it^{1, 3}. Momentous doesn’t name its supplier, and its guarantee has no stated terms⁴. Klean doesn’t give a net weight or a source, and it’s unknown whether the logged-out price applies to every buyer or whether an opened bottle can be returned^{8, 11}. BulkSupplements doesn’t say how much of the 300 mg is glycinate and how much is oxide, where the magnesium is made, or whether a given bag’s lot is covered by NSF’s listing^{17, 18}. Where a fact wasn’t stated, we left it unknown instead of guessing.

Where magnesium fits in the supplements guide

Magnesium is one of four supplements in the third-party-tested supplements guide, alongside creatine, omega-3 and vitamin D. For a two-product comparison, see Thorne vs Momentous Magnesium Bisglycinate. Reviews of all four: Thorne, Momentous, Klean and BulkSupplements.

For the same kind of price-per-serving comparison on another supplement, see best creatine supplements and when to take creatine. The trials behind all four supplements are in the evidence review. For fish oil, see best fish oil supplements. To see magnesium’s cost next to creatine, vitamin D and fish oil, see what the stack costs a month.

Sources

1. Magnesium Bisglycinate product page (SKU M204) Thorne · manufacturer
2. Returns and Exchanges Thorne · manufacturer
3. Certified for Sport listing: Thorne Magnesium Bisglycinate NSF · certifier
4. Magnesium Bisglycinate 200mg Momentous · manufacturer
5. Magnesium Bisglycinate listing on Momentous's store (price, SKU, weight and label photo descriptions) Momentous · manufacturer · price read from the store’s product data
6. Certified for Sport listing: Magnesium Bisglycinate (Momentous) NSF · certifier
7. Refund policy Momentous · manufacturer
8. Klean Magnesium product page (SKU KA202599-90) Klean Athlete · manufacturer
9. Klean Magnesium label and Supplement Facts (formula KA202599-90) Klean Athlete · manufacturer
10. Klean Magnesium product data sheet (copyright 2020) Klean Athlete · manufacturer
11. Return Policy Klean Athlete · manufacturer
12. Certified for Sport listing: Klean Magnesium (United States, unflavored) NSF Certified for Sport · certifier
13. Certified for Sport listing: Klean Magnesium (United States, flavor Other) NSF Certified for Sport · certifier
14. Klean Athlete shop address for magnesium (forwards to Klean Athlete's Amazon storefront) Klean Athlete · manufacturer
15. Magnesium Glycinate Powder BulkSupplements.com · manufacturer
16. Magnesium Glycinate Powder sizes and one-time prices BulkSupplements.com · manufacturer · price read from the store’s product data
17. Magnesium Glycinate Powder 500 g label (Supplement Facts) BulkSupplements.com · manufacturer
18. NSF/ANSI Standard 173 Dietary Supplements listing: Hard Eight Nutrition LLC dba BulkSupplements.com NSF · certifier
19. Refund policy BulkSupplements.com · manufacturer
20. Shipping policy BulkSupplements.com · manufacturer
21. Magnesium: Fact Sheet for Health Professionals NIH Office of Dietary Supplements · guideline
22. openFDA food enforcement reports, search for Hard Eight Nutrition U.S. Food and Drug Administration · regulator · data file
23. Hard Eight Nutrition LLC warning letter, Aug 27, 2015 (Internet Archive copy of FDA's page captured Apr 23, 2019) U.S. Food and Drug Administration · regulator
24. Hard Eight Nutrition LLC close-out letter, Feb 5, 2016 (Internet Archive copy of FDA's page captured Apr 25, 2019) U.S. Food and Drug Administration · regulator
25. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial (Schuster et al., Nat Sci Sleep 2025;17:2027-2040) Dove Medical Press · randomized trial
26. Certified for Sport listing: Magnesium Glycinate (Bulk Supplements) NSF Certified for Sport · certifier