Magnesium cost per dose compared: 13 supplements by real cost per 100 mg
A $17 bottle can be cheaper than a $16 one, and a 1 kg bag can cost less per serving than a 60-capsule jar. To compare magnesium supplements fairly, you need two numbers: cost per labelled serving and cost per 100 mg of actual magnesium. Here are both for 13 products.
Why price per bottle misleads
Bottles differ in three ways at once: how many servings they hold, how many capsules make a serving, and how much elemental magnesium each serving contains. A taurate bottle that says "1,500 mg" on the front holds 120 mg of magnesium per 3-capsule serving. A citrate bottle may hold 420 mg per 4-capsule serving. The price tag alone can't tell you which is cheaper. (If the label numbers confuse you, start with our label math guide.)
The two formulas
- Cost per labelled serving = price ÷ servings per container.
- Cost per 100 mg of magnesium = price ÷ (servings × mg magnesium per serving) × 100.
The second is the fairer comparison, because labelled servings vary so much. "Per dose" here means per serving as printed on the label. That's not a recommendation to take that amount.
13 products compared
| Product (brand store) | Form | Price | Mg per labelled serving | $ per serving | $ per 100 mg |
|---|---|---|---|---|---|
| BulkSupplements Magnesium Citrate powder, 500 g | Citrate powder | $22.97 | 400 mg | $0.16 | $0.04 |
| Nutricost Magnesium Malate, 180 capsules | Malate | $17.97 | 420 mg | $0.30 | $0.07 |
| Nutricost Magnesium Citrate, 240 capsules | Citrate | $19.97 | 420 mg | $0.33 | $0.08 |
| Nutricost Magnesium Chloride, 240 capsules | Chloride | $16.97 | 150 mg | $0.14 | $0.09 |
| Doctor's Best High Absorption Magnesium, 240 tablets | Glycinate chelate | $23.99 | 200 mg | $0.20 | $0.10 |
| Nutricost Magnesium Glycinate, 180 capsules | Glycinate | $16.97 | 210 mg | $0.28 | $0.13 |
| Natural Vitality CALM Magnesium Glycinate, 180 capsules | Glycinate | $35.89 | 325 mg | $0.60 | $0.18 |
| Nutricost Magnesium Taurate, 240 capsules | Taurate | $19.97 | 120 mg | $0.25 | $0.21 |
| BiOptimizers Magnesium Breakthrough, 60 capsules | Blend incl. oxide | $39.99 | 500 mg | $1.33 | $0.27 |
| Thorne Magnesium Bisglycinate powder, 60 scoops | Glycinate powder | $52.00 | 200 mg | $0.87 | $0.43 |
| Nature Made Zero Sugar Magnesium Citrate Gummies, 40 | Citrate gummy | $18.99 | 200 mg | $0.95 | $0.47 |
| Doctor's Best Brain Magnesium with Magtein, 90 capsules | L-Threonate | $37.99 | 150 mg | $1.27 | $0.84 |
| Momentous Magnesium L-Threonate, 90 capsules | L-Threonate | $49.99 | 144 mg | $1.67 | $1.16 |
Every price: brand store price, checked 21 Oct 2026. These are the brand's own web-store one-time prices before shipping, tax, coupons or subscriptions. Retailers and sales may be cheaper. Magnesium per serving is the elemental line from the brand page, the Supplement Facts image or the NIH Dietary Supplement Label Database. Serving sizes are as printed on labels and are not a suggestion to take that amount. Selected from the 30 products in the Magnesium Decoder.
What stands out
- Powders and budget capsules are cheapest. Budget citrate, malate, chloride and glycinate products with complete labels cost about 4 to 18 cents per 100 mg.
- Taurate looks expensive per milligram because it's only about 9% magnesium. That means more compound, and more capsules, for each 100 mg.
- Gummies cost more for the magnesium they carry. The citrate gummies cost $0.47 per 100 mg.
- Threonate is the most expensive form, at $0.84 to $1.16 per 100 mg in our table. That's roughly 6 to 9 times budget glycinate. Human trials of threonate are small and industry-linked, which the full guide covers in its own chapter.
- Premium isn't always pure. BiOptimizers Magnesium Breakthrough ($0.27 per 100 mg) contains some magnesium oxide, according to its own ingredient list.
What a higher price can buy
A higher price isn't automatically a rip-off. Some premium products were listed in the NSF Certified for Sport directory when we searched on 21 Oct 2026, including Thorne's bisglycinate powder and Momentous's threonate. That program tests for banned substances and checks that the label matches the contents. Other products may be tested by other programs, and "3rd-party tested" on a brand page is the company's own claim. Absorption matters too. Oxide is the cheapest per milligram on the label but was poorly absorbed in studies, so cheapest per 100 mg isn't the whole story. See glycinate vs citrate for how two well-absorbed forms compare.
Get the full 30-product table and the price calculator
The Magnesium Decoder ranks all 30 products, from $0.03 to $1.16 per 100 mg, with label sources and flags. It also lists 8 products we couldn't calculate and explains why. The Excel tracker calculates the cost of your own bottles.
Free 4-page sample (PDF, no email) See the Magnesium Decoder, $7
Magnesium forms on one page
How much of each form is actual magnesium (oxide ≈60%, citrate ≈16%, glycinate ≈14%, threonate ≈7–8%) and what the research says, in plain words. Free PDF. You also join the Renvo Life newsletter. We'll email you the link after you confirm.
Not medical advice.
How to price your own bottle
- Find the price you actually pay, including shipping if it applies.
- Find "Servings per container" and the "Magnesium" line on the Supplement Facts panel.
- Calculate price ÷ (servings × magnesium mg) × 100. That's your cost per 100 mg. The same sum is on the magnesium cost per 100 mg calculator.
- Compare it with the table above. If your bottle is far above the products in the same form, check whether you're paying for a brand, a certification or a label trick.
FAQ
What is the cheapest magnesium per 100 mg?
In our full 30-product table, BulkSupplements glycinate powder (which also lists oxide) and its oxide capsules came out at about $0.03 per 100 mg. Among the products in the table above, BulkSupplements citrate powder was cheapest at $0.04 (brand store prices, checked 21 Oct 2026).
Why use cost per 100 mg instead of cost per serving?
Labelled servings range from about 100 mg to 500 mg of magnesium, so cost per serving doesn't compare like with like.
Are Amazon prices cheaper?
Sometimes. We used brand store prices so every product was priced the same way on the same day. Your price may differ.
Does a cheaper form absorb worse?
Oxide is cheap per milligram but was poorly absorbed in studies. Citrate and glycinate were absorbed better than oxide and are also available cheaply.
Which one should I buy?
We don't recommend a specific product or amount. Ask your doctor or pharmacist which form and amount suit you, then use cost per 100 mg to compare options.
Related: How much elemental magnesium is in your supplement? · Magnesium glycinate vs citrate · The Magnesium Decoder · All guides
More in this series: buffered glycinate check · threonate: what the price buys · premium vs budget · why oxide is cheapest per mg · shopping by the numbers
Sources: NIH Office of Dietary Supplements, Magnesium fact sheet for health professionals; Walker et al. 2003 (Magnesium Research); Firoz & Graber 2001 (Magnesium Research); brand web stores and the NIH Dietary Supplement Label Database, checked 21 Oct 2026. No brand paid to appear, and there are no affiliate links on this page.
Health disclaimer. Not medical advice. This is a shopping and label guide. It doesn't diagnose, treat or recommend doses, and makes no promises of results. Check with your doctor or pharmacist before starting a supplement, especially if you have kidney disease, are pregnant, or take prescription medicines.
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Last updated 30 Oct 2026