Magnesium glycinate: elemental dose, label tricks, and how much for sleep
· 4 min read · By Value Servings
Magnesium glycinate is the form sleep forums crown as the best, and it is also the form with the most confusing labels. Two bottles that both say "400 mg" can differ several-fold in actual magnesium.
Compound weight vs elemental magnesium
A mineral supplement is the mineral bound to something else. For magnesium glycinate that is the amino acid glycine. Glycine is heavy, so most of the weight is not magnesium.
| Form | Magnesium by weight (approx.) | 500 mg of compound gives |
|---|---|---|
| Magnesium oxide | 60% | 300 mg magnesium |
| Magnesium citrate | 16% | 80 mg |
| Magnesium glycinate (bisglycinate) | 14% | 70 mg |
| Magnesium L-threonate | 7–8% | about 38 mg |
Approximate figures. Products vary by hydration and purity.
On the Supplement Facts panel, the amount next to "Magnesium" should be the elemental magnesium, with the form in parentheses: Magnesium (as magnesium bisglycinate) 200 mg. The front label is where the confusion lives. A front that says "Magnesium Glycinate 500 mg" may mean the compound. Always read the back.
The oxide blend problem
Pure bisglycinate cannot be much more than 14% magnesium. When a "glycinate" powder claims 20% or more, it is usually "buffered": mixed with magnesium oxide to raise the number cheaply. On the label, look at the parentheses. Magnesium (as magnesium bisglycinate, magnesium oxide) means a blend, and oxide may be the larger part.
Oxide is not dangerous. It is simply poorly absorbed and more likely to loosen stools, and it is not what people buying glycinate think they are getting. Our magnesium list includes glycinate and bisglycinate only, when the store page states the elemental amount. Oxide and blends stay off.
Price per 100 mg elemental
Because the elemental amount varies so much between products, the fair price is per 100 mg of magnesium, not per capsule or per bottle:
| Product | Store | Per 100 mg elemental | vs Pure Encapsulations |
|---|---|---|---|
| Micro Ingredients Pure Magnesium Glycinate 400mg Per Serving · 240 Capsules | Micro Ingredients | $0.06 | 73% less |
| NOW Foods Magnesium Bisglycinate Powder · 8 oz | NOW Foods | $0.06 | 73% less |
| Nutritionn Magnesium Glycinate (300 Capsules) | Nutritionn | $0.06 | 73% less |
| Piping Rock Magnesium Glycinate · 375 mg · 130 Quick Release Softgels | Piping Rock | $0.07 | 68% less |
| Nutricost Magnesium Glycinate Powder · Unflavored | Nutricost | $0.08 | 64% less |
| Pure Encapsulations Magnesium (Glycinate) · 180 Capsules popular brand | Pure Encapsulations | $0.22 | — |
Prices checked September 23, 2026. Store prices change; the price at checkout is final. See the full magnesium list
How much magnesium
- The RDA for adults is 400–420 mg a day for men and 310–320 mg for women, from food and supplements combined.
- The upper limit for supplemental magnesium is 350 mg a day for adults. Above that, diarrhea and cramps become common. Food magnesium does not count toward this limit.
- Many people get a good share from food: nuts, seeds, beans, whole grains, leafy greens.
People with kidney disease should not take magnesium supplements without a doctor, because the kidneys clear excess magnesium. Magnesium can also interfere with some antibiotics and osteoporosis drugs; separate the doses and ask a pharmacist.
Does magnesium help you sleep?
The evidence is thinner than the forums suggest. Small trials, mostly in older adults or people with low magnesium, found modest improvements in sleep measures. A 2021 review of trials in older adults called the evidence low quality: sleep onset improved by about 17 minutes on average. Larger, well-controlled trials are scarce, and many studies used forms other than glycinate. Glycine itself has some small studies on sleep quality, which may be part of glycinate's reputation.
If you try it, a common approach is 100–200 mg elemental in the evening, staying under the 350 mg supplemental limit. If glycinate seems to do nothing, it may be that your magnesium intake was already adequate.
Glycinate vs citrate vs threonate
- Glycinate: gentle on the gut, the default for daily use.
- Citrate: well absorbed, but more likely to loosen stools. Sometimes used deliberately for constipation.
- Oxide: cheap and high in magnesium per pill, poorly absorbed, often a laxative.
- Threonate: marketed for the brain. Very little magnesium per capsule, so it is by far the most expensive per 100 mg. Evidence for cognitive benefits in people is limited.
Frequently asked questions
How much elemental magnesium is in magnesium glycinate?
About 14% of the compound's weight. 1,000 mg of magnesium glycinate provides about 140 mg of magnesium. Check the Supplement Facts panel, which should state the elemental amount.
How much magnesium glycinate should I take for sleep?
Studies are small, but common amounts are 100–200 mg of elemental magnesium in the evening. Adults should stay at or under 350 mg a day of supplemental magnesium unless a doctor advises more.
Why did my magnesium glycinate do nothing?
You may not have been low in magnesium, the dose may have been smaller than you thought (compound vs elemental), or the product may have been a blend with oxide.
Is magnesium glycinate better than oxide?
For absorption and stomach comfort, yes. Oxide delivers more magnesium per pill on paper but less of it is absorbed, and it more often causes loose stools.
Can I take magnesium every night?
Many adults do, within the 350 mg supplemental limit. Ask a doctor if you have kidney problems or take medications that interact with magnesium.
Sources
Compare magnesium glycinate per 100 mg elementalEvery price on the list is worked out the same way, and checked daily.
This is general information about prices and labels, not medical advice. Ask a doctor or pharmacist before starting a supplement, especially if you are pregnant, take medication, or have a health condition. We don't sell the products; how we make money.