Which magnesium form has the most elemental magnesium?

Magnesium oxide, at roughly 60 percent elemental magnesium by weight, far more than any other common form. It is also among the least well absorbed, which is the reason a high elemental percentage on its own is a poor way to choose a product. Oxide is inexpensive and is often used to raise a headline milligram figure without raising the amount your body takes up.

What are the three families of magnesium forms?

Chelated forms such as magnesium bisglycinate and magnesium taurate bind magnesium to an amino acid. They are generally the gentlest on digestion and well absorbed, but lower in elemental magnesium per gram. Organic salts such as magnesium citrate, malate, L-threonate, orotate and aspartate are well absorbed and moderate in elemental content; citrate in particular has a laxative effect at higher intakes. Inorganic salts such as magnesium oxide, carbonate and chloride are high in elemental magnesium on paper but less well absorbed, with oxide the most likely to loosen the bowels. Because each family has a different profile, some products combine several forms in one complex.

How much elemental magnesium is in magnesium glycinate?

Roughly 14 percent by weight when the chelate is fully reacted, though published figures range from about 14 to 20 percent depending on the supplier and whether the material is partially or fully chelated. That means a 1000mg dose of the compound yields somewhere in the region of 140 to 200mg of actual magnesium. Always read the declared elemental figure on the panel rather than calculating from the compound weight yourself.

Is magnesium bisglycinate different from magnesium glycinate?

No, they are the same compound: magnesium chelated to two molecules of the amino acid glycine. The bis prefix simply makes the two-glycine structure explicit. Manufacturers use whichever name they prefer, so the naming difference tells you nothing about the product. Compare the elemental magnesium instead.

What is a buffered magnesium chelate?

A chelate that has been blended with magnesium oxide. Because oxide is around 60 percent elemental magnesium and a chelate is closer to 14 percent, adding oxide raises the elemental figure a label can declare while diluting the proportion that is actually chelated. Buffering is not dishonest in itself, but a buffered product is not a pure chelate and a label should make clear which it is. If a product declares an unusually high elemental figure for a chelate, buffering is the usual explanation.

Does a higher elemental percentage mean better absorption?

No. Elemental percentage describes how much of the compound weight is magnesium. Absorption describes how much of that magnesium is taken up by the body. They are separate properties and they do not track each other. Magnesium oxide illustrates the point: it has the highest elemental content of any common form and is among the least well absorbed. Solubility, the ligand and the dose all affect uptake.

Which magnesium form should I choose?

There is no single best form and no authorised UK or EU health claim distinguishes one magnesium form from another, so no form can lawfully be described as better for any outcome. Practical grounds to choose between them are elemental magnesium per serving, the percentage of the Nutrient Reference Value that represents, tolerability, serving size and cost per unit of elemental magnesium. Chelated forms such as bisglycinate are commonly chosen by people who find other forms unsettling to the stomach.

Why do the elemental percentages vary between sources?

Because the same named compound can differ in practice. Hydration state matters, since anhydrous magnesium citrate contains proportionally more magnesium than the hydrated form. Chelates vary by how completely they are reacted. Raw material specifications differ between suppliers. This is why the figures on this page are given as approximate ranges, and why the declared elemental figure on a specific product nutrition panel is always more reliable than a general table.

Magnesium Forms Explained: Elemental Content of Every Common Form

The Mineral Series · Reference

Magnesium forms, explained.

Magnesium is never sold on its own — it's always bound to something else, and that something else is most of the weight on the label. Here's how much actual magnesium each common form contains, and why the one with the highest percentage is usually the one you want least.

12 forms compared 375mg UK NRV 56.25mg the 15% claim threshold

Magnesium forms explained — elemental magnesium reference summary

Magnesium in supplements is always bound to another molecule, so the milligram figure printed on a pack is the weight of the whole compound rather than the weight of the magnesium. The magnesium fraction is called elemental magnesium. Magnesium forms fall into three families. Chelated forms such as magnesium bisglycinate and magnesium taurate bind magnesium to an amino acid, are generally the gentlest on digestion and are well absorbed, but are lower in elemental magnesium per gram. Organic salts such as magnesium citrate, malate, L-threonate, orotate and aspartate are well absorbed and moderate in elemental content, and high-dose citrate can have a laxative effect. Inorganic salts such as magnesium oxide, carbonate and chloride are high in elemental magnesium on paper but less well absorbed, with oxide the most likely to loosen the bowels. Approximate elemental magnesium by weight for the common forms: magnesium oxide around 60 percent; magnesium carbonate around 28 to 30 percent; magnesium malate around 15 percent; magnesium citrate around 11 to 16 percent depending on hydration state; magnesium glycinate and magnesium bisglycinate, which are the same compound, around 14 percent when fully reacted; magnesium chloride around 12 percent; magnesium lactate around 12 percent; magnesium sulfate around 10 percent; magnesium taurate around 9 percent; magnesium L-threonate around 8 percent; magnesium aspartate around 7 to 8 percent; magnesium orotate around 7 percent. These figures are approximate and vary with supplier, hydration state and how completely a chelate has been reacted. A high elemental percentage does not indicate good absorption. Magnesium oxide has the highest elemental content of any common form and is among the least well absorbed, which is why it is frequently used to raise a headline milligram figure at low cost. Elemental percentage and absorption are separate properties. A buffered chelate is a chelate blended with magnesium oxide. Because oxide is far higher in elemental magnesium than any chelate, buffering raises the elemental figure a label can declare while diluting the chelated fraction. The UK Nutrient Reference Value for magnesium is 375mg per day. A serving must provide at least 15 percent of that, equal to 56.25mg elemental magnesium, before a product may be described as a source of magnesium or carry any authorised magnesium health claim. UK guidance sets a safe upper level of 400mg per day for supplemental magnesium. No authorised United Kingdom or European Union health claim distinguishes one magnesium form from another. Forms may be compared on elemental content, percentage of the Nutrient Reference Value, tolerability and cost — not on outcomes.

Start Here

The number on the front is not the magnesium.

A pouch that says "Magnesium Citrate 1000mg" is telling you the weight of magnesium citrate, not the weight of magnesium. Citrate is a fairly heavy molecule, and most of that 1000mg is citrate. The magnesium itself — the part your body is actually short of — might be 110mg or so.

This is normal, legal and universal. Every magnesium supplement works this way, because elemental magnesium is a reactive metal that can't be put in a capsule on its own. It has to be bound to something. But it means the headline milligram figure is close to useless for comparing products, and the number that matters is in the nutrition panel: the declared elemental magnesium and its percentage of the Nutrient Reference Value.

The UK NRV for magnesium is 375mg per day. A serving has to provide at least 15% of it — 56.25mg elemental magnesium — before a product can even be called a source of magnesium, let alone carry one of the authorised magnesium health claims.

The Three Families

Every magnesium form is one of three things.

Before the individual numbers, it helps to know the groupings — because the trade-off between elemental content and absorption runs along these lines.

Chelated forms

Bisglycinate · taurate

Magnesium bound to an amino acid. Generally the gentlest on digestion and well absorbed, but lower in elemental magnesium per gram — you need more compound to get the same mineral.

Organic salts

Citrate · malate · threonate · orotate · aspartate

Magnesium bound to an organic acid. Well absorbed and moderate in elemental content. High-dose citrate has a laxative effect — useful to some people, a problem for others.

Inorganic salts

Oxide · carbonate · chloride

Magnesium bound to a mineral counterion. High in elemental magnesium on paper but less well absorbed; oxide is the most likely to loosen the bowels.

Because each family has a different profile, some products combine several forms in one complex rather than committing to one — that's the logic behind multi-form magnesium blends.

The Ladder

Every common form, by elemental content.

Approximate elemental magnesium as a percentage of compound weight. Bars scaled to magnesium oxide at 60%, the highest of any common form.

Magnesium oxideInorganic. Cheap, high elemental content, poorly absorbed. Common bulking agent in "high strength" products.

~60%

Magnesium carbonateInorganic. Converts to chloride in stomach acid. Also used as an antacid.

~28–30%

Magnesium malateOrganic salt. Bound to malic acid. Middling elemental content, generally well tolerated.

~15%

Magnesium citrateOrganic salt. Widely used and inexpensive. Laxative effect at higher intakes. Anhydrous forms sit at the top of this range.

~11–16%

Magnesium glycinate / bisglycinateChelate. The same compound under two names. Bound to two glycine molecules. Commonly chosen for tolerability.

~14% (14–20% quoted)

Magnesium chlorideInorganic. Highly soluble. Also the form used in topical magnesium products.

~12%

Magnesium lactateOrganic salt. Bound to lactic acid. Soluble, generally gentle on the stomach.

~12%

Magnesium sulfateInorganic. Epsom salts. Mostly used in baths rather than capsules.

~10%

Magnesium taurateChelate. Bound to taurine. Low elemental content — check the declared figure carefully.

~9%

Magnesium L-threonateOrganic salt. Bound to threonic acid. The lowest-elemental forms need the largest serving sizes.

~8%

Magnesium aspartateOrganic salt. Bound to aspartic acid.

~7–8%

Magnesium orotateOrganic salt. Bound to orotic acid. The lowest elemental content of the common forms.

~7%

Figures are approximate and vary with supplier, hydration state and how completely a chelate has been reacted — anhydrous salts carry proportionally more magnesium than hydrated ones. Always treat the elemental figure declared on a specific product's nutrition panel as more reliable than any general table, including this one.

The trap

The form with the most magnesium is the one you least want.

Look at the ladder again. Magnesium oxide is roughly four times higher in elemental magnesium than any chelate. If elemental content were the whole story, oxide would win every comparison and nothing else would exist.

It doesn't, because elemental percentage and absorption are separate properties. Elemental percentage tells you how much of the compound's weight is magnesium. Absorption tells you how much of that magnesium your body actually takes up. Oxide is poorly soluble and among the least well absorbed of the common forms — so a large declared figure translates to a much smaller delivered one.

This is exactly why oxide is so common in cheap "high strength" magnesium products. It lets a manufacturer print a big number on the front at very low cost. If a budget product declares an unusually high elemental magnesium figure, oxide is almost always the reason.

None of which makes oxide worthless — it's inexpensive and it does contain magnesium. It makes the headline number an unreliable guide on its own. Read the form, then the elemental figure, then the %NRV, in that order.

Watch For This

Buffered chelates, and the maths that gives them away.

A "buffered" magnesium chelate is a chelate blended with magnesium oxide. Because oxide sits around 60% elemental and a chelate sits around 14%, adding oxide raises the elemental figure the label can declare — while reducing the proportion that is genuinely chelated.

Buffering isn't dishonest in itself, and plenty of reputable products are buffered. The problem is when it isn't disclosed, because the buyer thinks they're getting a pure chelate at an unusually good elemental figure when they're getting a partial one.

The tell is arithmetic. If a product claims to be magnesium bisglycinate and declares an elemental figure much above roughly 20% of the stated compound weight, something other than pure chelate is contributing. That doesn't automatically mean a bad product — it means the label should say so, and you should know what you're comparing.

A worked example

Label says	Declared elemental	Implied %	What that suggests
1040mg magnesium bisglycinate	208mg	20%	Consistent with a fully reacted chelate at the top of the normal range
1000mg magnesium bisglycinate	140mg	14%	Consistent with a fully reacted chelate
1000mg "magnesium bisglycinate"	400mg	40%	Far above what a pure chelate yields — buffering with oxide is the likely explanation
500mg magnesium glycinate	70mg	14%	Consistent with a fully reacted chelate

The highlighted row is our own Magnesium Bisglycinate, shown so you can run the same check on us that we're suggesting you run on everyone else.

Choosing

So which form should you take?

Here is the part most pages get wrong: no authorised UK or EU health claim distinguishes one magnesium form from another. Nobody may lawfully tell you that glycinate is better for sleep, that taurate is better for the heart, or that threonate is better for the brain. Those claims are not authorised, and a brand making them is telling you something about how carefully it reads the rules.

What you can compare, honestly:

Compare on	Why it's a fair basis
Elemental magnesium per serving	The only figure comparable across every form and every brand
% of the 375mg NRV	Tells you where a serving sits, and whether it clears the 15% threshold at all
Tolerability	Citrate has a laxative effect at higher intakes; chelates are commonly chosen by people who find other forms unsettling
Serving size	Low-elemental forms need more capsules to reach the same magnesium — check how many you'd actually swallow
Cost per unit of elemental magnesium	Not cost per capsule, and not cost per compound milligram
Chelate disclosure	Whether the product states if it's fully reacted or buffered

For transparency: Vitality sells magnesium as bisglycinate, glycinate and a multi-form blend. We don't sell standalone citrate, malate, taurate, threonate or orotate — so this page isn't steering you toward a range we happen to stock. If a different form suits you better, buy it elsewhere.

The Range

The products behind this guide.

Vitality Magnesium Bisglycinate 208mg elemental magnesium capsules, UK manufactured

Vitality Magnesium Glycinate 500mg capsules, 70mg elemental magnesium per serving

Vitality Ultimate 8 Magnesium 1000mg multi-form magnesium capsules

Bisglycinate (208mg elemental, 55% NRV) · Glycinate 500mg (70mg elemental, 18.7% NRV) · Ultimate 8 multi-form (375mg elemental, 100% NRV). UK manufactured, independently batch tested.

Next step

Now compare the actual products.

Our ranked guide applies everything on this page to the formulas in our own range — judged on elemental magnesium, not compound weight, with the trade-offs stated.

Best magnesium glycinate UK Shop magnesium

FAQs

Common questions.

Magnesium oxide, at roughly 60% by weight — far more than any other common form. It's also among the least well absorbed, which is exactly why a high elemental percentage on its own is a poor way to choose. Oxide is cheap and frequently used to raise a headline milligram figure without raising what your body takes up.

Chelated forms (bisglycinate, taurate) bind magnesium to an amino acid — gentlest on digestion, well absorbed, lower in elemental magnesium per gram. Organic salts (citrate, malate, L-threonate, orotate, aspartate) are well absorbed and moderate in elemental content; citrate is laxative at higher intakes. Inorganic salts (oxide, carbonate, chloride) are high in elemental magnesium on paper but less well absorbed, with oxide most likely to loosen the bowels. Some products combine several forms in one complex.

Roughly 14% by weight when fully reacted, though published figures range from about 14% to 20% depending on supplier and how completely the chelate is reacted. A 1000mg dose of the compound therefore yields somewhere around 140–200mg of actual magnesium. Read the declared elemental figure rather than calculating it yourself.

No — same compound. Magnesium chelated to two molecules of glycine. The "bis" prefix just makes the two explicit. Manufacturers use whichever name they prefer, so the naming tells you nothing. See our magnesium glycinate buying guide for how this plays out across real products.

A chelate blended with magnesium oxide. Oxide is ~60% elemental and a chelate ~14%, so adding oxide lifts the declarable elemental figure while diluting the chelated fraction. Not dishonest in itself — but a buffered product isn't a pure chelate and the label should say which it is. An unusually high elemental figure on a "chelate" is the usual tell.

No — they're separate properties. Elemental percentage is how much of the compound's weight is magnesium. Absorption is how much of that magnesium you take up. Oxide proves the point: highest elemental content of any common form, and among the least well absorbed. Solubility, the ligand and the dose all affect uptake.

There's no single best form, and no authorised UK or EU claim distinguishes them, so no form can lawfully be described as better for any outcome. Compare instead on elemental magnesium per serving, %NRV, tolerability (citrate is laxative at higher intakes), serving size and cost per unit of elemental magnesium.

Because the same named compound differs in practice. Hydration state matters — anhydrous citrate carries proportionally more magnesium than the hydrated form. Chelates vary by how completely they're reacted. Supplier specifications differ. That's why this page gives ranges, and why a specific product's declared figure always beats a general table.

375mg per day. A serving must provide at least 15% — 56.25mg elemental — before a product may be called a source of magnesium or carry an authorised magnesium claim. Separately, UK guidance sets a safe upper level of 400mg per day for supplemental magnesium, not counting magnesium from food. See our magnesium dosage guide.

Keep going.

About this guide

Last reviewed 17 August 2026 by the Vitality Supplements Editorial Team, written to our published editorial standards and quality & testing policy. We are a UK supplement manufacturer and we sell magnesium, which we disclose openly. Elemental percentages here are given as approximate ranges because the underlying figures genuinely vary by supplier, hydration state and degree of chelation — we would rather show a range than a falsely precise number. We have included a worked example that lets you apply the same buffering check to our own product as to anyone else's, and we have stated which magnesium forms we do not sell.

Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. Do not exceed the stated recommended daily dose. UK guidance sets a safe upper level of 400mg per day for supplemental magnesium. Authorised GB and EU health claims for magnesium require a serving providing at least 15% of the 375mg Nutrient Reference Value; no authorised claim distinguishes between magnesium forms, and claims relating to sleep, cramp prevention or anxiety are not authorised and are not made here. If you are pregnant, breastfeeding, taking medication or under medical care, consult a healthcare professional before use — magnesium can interact with certain antibiotics and other medicines. This page is general information, not medical advice, and is not intended to diagnose, treat or prevent any condition. Every Vitality batch is independently tested. UK manufactured. Free UK delivery. 60-day satisfaction guarantee on first purchase. Certificate of Analysis available on request. Privacy · Terms · info@vitality-supplements.co.uk