The Magnesium Truth Calculator
What’s actually in your magnesium supplement?
Most magnesium labels show an impressive number, but that number isn't the magnesium your body actually gets. The real figure, elemental magnesium, is often a fraction of what it appears to be, in some cases less than half. Many products claim more elemental magnesium than the stated form can chemically deliver.
We built a free magnesium calculator so you can check how much elemental magnesium your supplement really contains, in under a minute.
Enter what's on your label and we'll show you what the science actually says.
Unfortunately we can't calculate your elemental magnesium without the mg amounts from your label. However, this would raise concerns as to why they aren't showing transparency on their labels. Please contact your supplier for the breakdown and come to the calculator.
Elemental magnesium breakdown
Per-form amounts are shown to one decimal place; totals are rounded to the nearest milligram.
Most people are low in magnesium and don't know it.
The daily minimum magnesium your body needs
375mg is the daily minimum recommendation for magnesium, but required levels vary for everyone. Modern life, such as stress, processed food, and poor soil quality, depletes it constantly. Most people are already running low; your magnesium supplement is designed to fill that gap.
The maximum magnesium glycinate can deliver
Magnesium glycinate contains a maximum of 12% elemental magnesium by weight. The other 88% is glycine - an amino acid, not magnesium. If a label claims more than 12% glycinate, the maths don’t add up. For example, if a magnesium glycinate supplement declared 1000 mg of magnesium glycinate, 12% of this would be elemental magnesium = 120 mg, and the remainder would be the amino acid glycine = 880 mg.
Milligrams missing from one top-selling label
We checked a leading UK magnesium supplement. The label claimed 383mg of elemental magnesium. The chemistry of the declared forms allows 244. That 140mg gap has to come from somewhere undisclosed.
What a good label looks like
Three columns. Every form.
This is what a transparent magnesium label looks like. Every form is declared, and every elemental percentage is shown.
| Per 2 capsules | Amount | Elemental Mg | %NRV |
|---|---|---|---|
| Aquamin Marine Magnesium | 400mg | 132mg | 36% |
| Magnesium Citrate | 316mg | 51mg | 14% |
| Magnesium Glycinate | 350mg | 42mg | 12% |
| Magnesium Malate | 300mg | 42mg | 11% |
| Magnesium Oxide | 180mg | 108mg | 28% |
| Total Magnesium | 375mg | 100% |
The form - what carries the magnesium
Each ingredient is a magnesium compound - the magnesium molecule bonded to a carrier. Different forms have different elemental percentages, absorption rates and therapeutic uses. All should be declared individually.
The amount - total compound per serving
This is the total weight of the compound, including the carrier. This is not the amount of magnesium your body gets; it’s the larger number and the one most brands lead with on their label.
Elemental magnesium - the only number that matters
This is how much actual magnesium each form contains. Your body can only use the elemental fraction. If a label doesn’t show this column, you cannot know what you are getting.
% NRV - your daily contribution
The percentage of the 375mg daily minimum that each form contributes. When all forms are declared, these should add up to 100% - or close to it. If the total NRV appears high for the listed forms, use our calculator.
Frequently asked questions
What's the difference between buffered and unbuffered magnesium?
A buffered magnesium supplement blends a cheaper, high-elemental form (typically magnesium oxide) into a formula alongside well-known forms like glycinate or citrate, without declaring the oxide on the label. The result: the elemental magnesium figure appears high (because oxide delivers 60% elemental by weight), but the ‘premium’ forms listed cannot chemically account for it. The consumer pays premium prices for a product that is substantially magnesium oxide. Unbuffered magnesium declares every form individually, with the amount and elemental contribution of each shown separately. Ultimately, what you see is what you get.
Magnesium oxide is not bad. Undisclosed oxide is. There is a meaningful difference between a product that openly uses oxide and one that uses it without telling you.
Why does elemental magnesium mean?
Magnesium supplements do not contain pure magnesium; the element is too reactive to exist on its own. Instead, magnesium is bonded to a carrier molecule: glycine (in glycinate), citric acid (in citrate), malic acid (in malate), etc.
Elemental magnesium is the actual magnesium content - the part your body can absorb and use. The carrier molecule is not magnesium. It does contribute to your daily intake.
Magnesium glycinate, for example, is 12% elemental magnesium by weight. So from 1000mg of glycinate, your body receives a maximum of 120mg of actual magnesium. The other 880mg is glycine.
The elemental figure is the only number that tells you how much magnesium you are actually taking. Everything else on the label is context for that number.
How much magnesium do I actually need?
The recommended daily minimum is 375mg of elemental magnesium. This is the baseline for a healthy adult.
Most people do not reach 375mg from diet alone. Modern processing, depleted soil, and high-stress lifestyles all reduce dietary magnesium intake. Supplementation is often needed to meet even the minimum requirement.
Some people, particularly those managing conditions such as migraines, fibromyalgia, perimenopause symptoms or chronic stress, may benefit from higher intakes. This is best discussed with your healthcare professional.
When you check your label with our calculator, you will see the exact %NRV each form contributes. This tells you whether your supplement is helping you reach the 375mg minimum - or falling short.
Why would I take different forms of magnesium?
Different forms of magnesium have distinct properties beyond their elemental composition. The carrier molecule matters.
Glycinate: The glycine carrier has a documented role in sleep quality and nervous system regulation, independent of the magnesium itself. Glycinate makes sense if sleep or anxiety is your primary goal, but not because it is “gentler.” It is gentler because it delivers less magnesium per milligram. A smaller dose of citrate or oxide would achieve the same effect at lower cost.
Citrate: Higher elemental content (16%) and a mild osmotic effect on the bowel. Often used for gut motility and general supplementation. Works well in powder form.
Malate: The malate carrier is involved in the Krebs cycle. This is a key metabolic process which takes place in the mitochondria of your cells. This is where carbohydrates, proteins, and fats are broken down to generate adenosine triphosphate (ATP), the primary energy source fueling your body.
Oxide: Highest elemental content at 60%. Delayed release in the gut makes it effective for migraines. Often dismissed as “low quality”, but research on its specific therapeutic uses is stronger than its reputation suggests, particularly for brain health.
Five forms of magnesium. two capsules daily. Everything your body needs magnesium for.. The key is knowing what is in it and in what amounts.