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Cheapest Magnesium (from magnesium oxide) on iHerb

Ranked by real cost per 100 mg of Magnesium (from magnesium oxide) — cheapest value first.

Prices updated Jul 25, 2026 · 25 products · Prices in USD

The priciest option here costs about 24.8× more per 100 mg of Magnesium (from magnesium oxide) than the best-value pick Best Naturals. For the same daily dose, choosing by cost per unit instead of sticker price can meaningfully cut your yearly spend.
#ProductDoseServingsPrice (USD)Cost per 100 mg
1
Best Naturals, Magnesium Oxide, 500 mg , 180 Tablets
Best Naturals, Magnesium Oxide, 500 mg , 180 Tablets
Best Naturals
500 mg18011.990.013View on iHerb →
2
Swanson, Magnesium Oxide, 200 mg, 500 Capsules
Swanson, Magnesium Oxide, 200 mg, 500 Capsules
Swanson
400 mg25018.990.019View on iHerb →
3
Swanson, Magnesium Oxide, 250 Capsules (200 mg per Capsule)
Swanson, Magnesium Oxide, 250 Capsules (200 mg per Capsule)
Swanson
400 mg12512.690.025View on iHerb →
4
Carlson, Magnesium Gels, 400 mg, 250 Soft Gels
Carlson, Magnesium Gels, 400 mg, 250 Soft Gels
Carlson
400 mg25025.420.025View on iHerb →
5
Carlson, Magnesium, 350 mg, 90 Capsules
Carlson, Magnesium, 350 mg, 90 Capsules
Carlson
350 mg909.950.032View on iHerb →
6
Carlson, Magnesium Gels, 400 mg, 100 Soft Gels
Carlson, Magnesium Gels, 400 mg, 100 Soft Gels
Carlson
400 mg10012.670.032View on iHerb →
7
Swanson, Liquid Calcium & Magnesium , 200 Softgels
Swanson, Liquid Calcium & Magnesium , 200 Softgels
Swanson
300 mg10012.410.041View on iHerb →
8
Kirkman Labs, Buffered Magnesium Oxide, 180 mg, 250 Capsules
Kirkman Labs, Buffered Magnesium Oxide, 180 mg, 250 Capsules
Kirkman Labs
180 mg25019.600.044View on iHerb →
9
Sports Research, Magnesium Oxide, 420 mg, 90 Softgels
Sports Research, Magnesium Oxide, 420 mg, 90 Softgels
Sports Research
420 mg9017.970.048View on iHerb →
10
Swanson, Liquid Calcium & Magnesium, 100 Softgels
Swanson, Liquid Calcium & Magnesium, 100 Softgels
Swanson
300 mg508.990.060View on iHerb →
11
NaturesPlus, Source of Life®, Green and Red Mini-Tabs, 180 Tablets
NaturesPlus, Source of Life®, Green and Red Mini-Tabs, 180 Tablets
NaturesPlus
100 mg302.000.067View on iHerb →
12
California Gold Nutrition, Magnesium Chelate with Calcium, 270 Tablets
California Gold Nutrition, Magnesium Chelate with Calcium, 270 Tablets
California Gold Nutrition
210 mg13519.900.070View on iHerb →
13
KAL, Calcium+, 200 Softgels
KAL, Calcium+, 200 Softgels
KAL
500 mg6625.690.078View on iHerb →
14
KAL, Cal-Citrate+, D3 & Magnesium, 240 Tablets
KAL, Cal-Citrate+, D3 & Magnesium, 240 Tablets
KAL
500 %6024.490.082View on iHerb →
15
Best Naturals, Coral Calcium Plus, 250 Capsules
Best Naturals, Coral Calcium Plus, 250 Capsules
Best Naturals
125 mg12512.910.083View on iHerb →
16
KAL, Cal/Mag/Zinc, High Potency , 100 Tablets
KAL, Cal/Mag/Zinc, High Potency , 100 Tablets
KAL
400 mg3311.790.089View on iHerb →
17
NOW Foods, Triphala, 120 Tablets
NOW Foods, Triphala, 120 Tablets
NOW Foods
200 mg6012.240.102View on iHerb →
18
Swanson, Calcium Citrate Plus Magnesium, 150 Vegan Capsules
Swanson, Calcium Citrate Plus Magnesium, 150 Vegan Capsules
Swanson
150 mg7513.390.119View on iHerb →
19
NOW Foods, Calcium Citrate Caps, 240 Veg Capsules
NOW Foods, Calcium Citrate Caps, 240 Veg Capsules
NOW Foods
225 mg8022.040.122View on iHerb →
20
BioSchwartz, Premium Ultra Pure Bone Strength, Calcium + D3, K2 & Magnesium, 120 Capsules
BioSchwartz, Premium Ultra Pure Bone Strength, Calcium + D3, K2 & Magnesium, 120 Capsules
BioSchwartz
380 mg3018.970.166View on iHerb →
21
KAL, Calcium Citrate+, Mixed Fruit, 60 Chewables
KAL, Calcium Citrate+, Mixed Fruit, 60 Chewables
KAL
250 mg3012.890.172View on iHerb →
22
Carlson, Calcium & Magnesium Gels with Vitamin D3, 100 Soft Gels
Carlson, Calcium & Magnesium Gels with Vitamin D3, 100 Soft Gels
Carlson
200 mg5017.940.179View on iHerb →
23
NaturesPlus, Source of Life®, Original Tablets, Multivitamin & Mineral Supplement, 30 Tablets
NaturesPlus, Source of Life®, Original Tablets, Multivitamin & Mineral Supplement, 30 Tablets
NaturesPlus
100 mg6014.830.247View on iHerb →
24
Swanson, Multi without Iron + Immune Support, High Potency, 120 Softgels
Swanson, Multi without Iron + Immune Support, High Potency, 120 Softgels
Swanson
100 mg6018.990.317View on iHerb →
25
Solaray, 2:1 Ratio Cal-Mag, 120 VegCaps
Solaray, 2:1 Ratio Cal-Mag, 120 VegCaps
Solaray
300 mg3029.690.330View on iHerb →

How we rank Magnesium (from magnesium oxide)

Two supplements can list the same dose per serving yet cost very differently once you account for how many servings are in the bottle. We calculate the total nutrient in each container (dose per serving × servings per container), divide the current price by that total, and rank by the resulting cost per unit. Lower is better. Because prices are refreshed automatically, this ranking reflects today's iHerb pricing rather than a snapshot from months ago.

Cost per unit is a starting point, not the whole story — the ideal form, third-party testing, and other ingredients matter too. Always check the label and consult a healthcare professional before starting a supplement.

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Prices update automatically and may differ from iHerb at checkout. Rankings are based on cost per unit of the listed nutrient and are for informational purposes only — not medical advice. Links to iHerb are affiliate links.