How much magnesium is in magnesium glycinate?

The short answer

• Magnesium glycinate is about 14% magnesium by weight. So 400 mg of magnesium glycinate holds about 56 mg of magnesium.
• The number to read is the one on the Magnesium line of the Supplement Facts panel. That's the magnesium itself; the compound in brackets after it ("as magnesium glycinate") is only where it comes from.
• The study figure (300 mg a day) and the US upper limit for supplements (350 mg a day) both count magnesium, not the compound.
• 11 of the 21 magnesium supplements on the site use a glycinate. One serving gives 60 mg to 350 mg of magnesium. Taken as directed, 3 land between 300 mg and 350 mg a day, 4 stay below 300 mg, and 4 can go over 350 mg.

Which number on the label is the magnesium?

Magnesium in a supplement is always bound to something: glycine, citric acid, oxygen, threonic acid. The whole compound weighs much more than the magnesium in it. US labeling rules make the Supplement Facts panel give the amount of the nutrient by weight, and let the label name the source in brackets after it, preceded by "as" or "from". The rule's own example is "Calcium (as calcium carbonate)" (21 CFR 101.36).

So on a panel like this, the magnesium is 60 mg, not 400:

That's a real label: Double Wood Supplements Magnesium Glycinate 400 mg. Its name says 400 mg, and the label adds "Magnesium glycinate 400 mg per capsule". That's the weight of the compound. The panel gives 60 mg of magnesium per capsule, close to the 56 mg the chemistry predicts.

How much of magnesium glycinate is magnesium

Magnesium glycinate is one magnesium atom bound to two molecules of glycine, an amino acid (PubChem lists it as magnesium bis(2-aminoacetate), C₄H₈MgN₂O₄). The whole molecule weighs 172.42 g per mole, and the magnesium in it 24.305. That's 14.1%: about a seventh of the weight is magnesium. "Magnesium bisglycinate" on a label is the same compound.

That's the pure compound. What a maker buys can differ: some products mix in other forms, and a chelate made with two amino acids, like magnesium lysinate glycinate, weighs more for the same magnesium. That's why we never work it out ourselves when the label gives the magnesium: the panel's Magnesium line is the figure every verdict on this site uses.

The bigger number on 9 labels

Most magnesium labels on the site print only the magnesium. But 9 of the 21 print a bigger number for the same serving: 7 on the facts panel itself, as the weight of the compound in brackets, and 2 in the product's name.

A number in a product's name isn't consistent either. Of the 6 magnesium products here with milligrams in their name, 4 name the magnesium in a serving and 2 name the weight of the compound (Double Wood Supplements Magnesium Glycinate 400 mg: 60 mg of magnesium and Nutricost Magnesium Oxide 375 mg: 210 mg of magnesium). Read the panel, not the front of the bottle.

What the dose figures count

A meta-analysis of 34 trials found that magnesium supplements at a median of 368 mg a day raised blood magnesium, and that 300 mg a day was enough to do it (Zhang et al., 2016). The US upper limit for magnesium from supplements is 350 mg a day; it doesn't count the magnesium in food (Matek Sarić et al., 2025). The RDA, 400–420 mg a day for men and 310–320 mg for women, does count food, so it isn't a target for a supplement on its own.

All three are milligrams of magnesium. So a label is judged on its Magnesium line, per day, at the most its directions give: 300 mg or more is marked Effective dose, less is Below research dose, and more than 350 mg is Over the upper limit.

Every magnesium label on the site, per day

Taken the way each label says, 4 of the 21 land between 300 mg and 350 mg a day, 9 stay below 300 mg, and 8 can go over 350 mg at the most their directions allow. For 2 of those 8, the least the directions give stays within the limit.

The magnesium glycinate labels

These are the 11 labels whose magnesium comes from a glycinate, alone or with other forms:

For 4 of them, reaching 300 mg a day would take more capsules than the label directs: Double Wood Supplements Magnesium Glycinate 400 mg (5 capsules a day), Puritan's Pride Magnesium Glycinate (3 capsules a day), Pure Encapsulations Magnesium (Glycinate) (3 capsules a day) and Natural Vitality Calm Capsules (6 capsules a day). Each product page shows the arithmetic.

Is glycinate better than other forms?

This guide doesn't rank forms. Every verdict on this site counts milligrams of magnesium, whatever it's bound to, because that's what the study figure and the upper limit count. A form with less magnesium by weight, like glycinate or threonate, simply needs a heavier capsule, or more of them, to give the same milligrams.

Reading your own bottle

1. Find the line that starts with Magnesium on the Supplement Facts panel. Its amount is the magnesium. Ignore the compound's weight in brackets, and any number in the product's name.
2. Check the serving size: is that amount for one capsule, or two, or three?
3. Multiply by the servings a day the directions give, at the least and at the most.
4. Compare it with 300 mg a day, the study figure, and 350 mg a day, the upper limit for magnesium from supplements.

Or find your bottle on the magnesium supplements page, or paste its label, and we'll do the counting, with every step shown. The magnesium guide has the research dose and sources.

Sources

• Zhang X, Li Y, Del Gobbo LC, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension. 2016;68(2):324-333. doi:10.1161/HYPERTENSIONAHA.116.07664
• Matek Sarić M, Sorić T, Juko Kasap Ž, et al. Magnesium: health effects, deficiency burden, and future public health directions. Nutrients. 2025;17(22):3626. doi:10.3390/nu17223626
• PubChem: magnesium glycinate, CID 84645 (C₄H₈MgN₂O₄, 172.42 g/mol); magnesium, CID 5462224 (24.305 g/mol). pubchem.ncbi.nlm.nih.gov/compound/84645
• 21 CFR 101.36, nutrition labeling of dietary supplements: the amount of each dietary ingredient by weight, and its source named "as" or "from". ecfr.gov
• Label amounts: each product's label as imported, with its source and date on the product page.
• How we judge magnesium per day, and every other ingredient: our methodology.