Why the compound matters
The partner adds weight but no magnesium. The bigger the partner, the less you get per mg.
Oxide’s partner is one small oxygen atom, so oxide is mostly magnesium. Glycinate’s partner is two lots of glycine, so it’s mostly glycine.
Why it matters to you: you need about 166 mg of oxide for 100 mg of magnesium, but about 710 mg of glycinate. So the front weight tells you little until you know the compound.
The share of magnesium in each compound
Our maths uses this table. “Compound for 100 mg” is how much you need for 100 mg of magnesium. Tap “Show the chemistry” for the formula behind each share.
| Compound | Share that is magnesium | Compound for 100 mg | Version used |
|---|---|---|---|
| bisglycinate | 14.1 % | 709 mg | dry (anhydrous)Show the chemistryFormula and weight: Mg(C2H4NO2)2, molar mass 172.42 g/mol; also sold as magnesium glycinate or diglycinate. Exact share: 0.1410. reference (opens in a new tab) Also magnesium glycinate dihydrate: 0.1166. |
| citrate | 16.2 % | 619 mg | trimagnesium dicitrate, dryShow the chemistryFormula and weight: Mg3(C6H5O7)2, molar mass 451.11 g/mol. Exact share: 0.1616. reference (opens in a new tab) Also magnesium citrate 1:1, MgHC6H5O7, anhydrous: 0.1134. Also trimagnesium dicitrate nonahydrate: 0.1189. |
| oxide | 60.3 % | 166 mg | magnesium oxideShow the chemistryFormula and weight: MgO, molar mass 40.30 g/mol. Exact share: 0.6030. reference (opens in a new tab) |
| chloride | 12 % | 836 mg | hexahydrate (the usual one)Show the chemistryFormula and weight: MgCl2.6H2O, molar mass 203.30 g/mol. Exact share: 0.1196. reference (opens in a new tab) Also magnesium chloride, anhydrous: 0.2553. |
| malate | 15.5 % | 644 mg | dry (anhydrous)Show the chemistryFormula and weight: MgC4H4O5, molar mass 156.38 g/mol. Exact share: 0.1554. reference (opens in a new tab) |
| L-threonate | 8.3 % | 1,212 mg | pure compoundShow the chemistryFormula and weight: Mg(C4H7O5)2, molar mass 294.50 g/mol. Exact share: 0.0825. reference (opens in a new tab) Also Magtein label basis, 144 mg Mg per 2000 mg: 0.0720. |
| taurate | 8.9 % | 1,121 mg | magnesium taurateShow the chemistryFormula and weight: Mg(C2H6NO3S)2, molar mass 272.57 g/mol. Exact share: 0.0892. reference (opens in a new tab) |
| orotate | 7.3 % | 1,376 mg | dry (anhydrous)Show the chemistryFormula and weight: Mg(C5H3N2O4)2, molar mass 334.50 g/mol. Exact share: 0.0727. reference (opens in a new tab) Also magnesium orotate dihydrate: 0.0656. |
| aspartate | 7.5 % | 1,335 mg | dihydrateShow the chemistryFormula and weight: Mg(C4H6NO4)2.2H2O, molar mass 324.53 g/mol, the hydrate commonly printed on Australian labels. Exact share: 0.0749. reference (opens in a new tab) Also magnesium aspartate, anhydrous: 0.0842. Also magnesium aspartate tetrahydrate: 0.0674. |
| amino acid chelate (unspecified) | not defined | no single figure | Label names no amino acid or ratio |
| phosphate | 27.7 % | 360 mg | dry (anhydrous)Show the chemistryFormula and weight: Mg3(PO4)2, molar mass 262.855 g/mol: 72.915 / 262.855 = 0.2774. Exact share: 0.2774. reference (opens in a new tab) Also trimagnesium phosphate pentahydrate: 0.2066. Also trimagnesium phosphate octahydrate: 0.1792. |
The names on Australian labels
- Glycinate, bisglycinate, diglycinate
- One compound, three names. It’s about 14 % magnesium. You may also see “glycinate chelate”.
- Amino acid chelate
- If the label names glycine, it’s glycinate. If it names no amino acid, the share can’t be known. Products we list with that wording: about 12 % to 20 %.
- Buffered
- Usually glycinate mixed with oxide to raise the magnesium per tablet. That makes it a blend.
- Heavy or light magnesium oxide
- The same thing as a dense or light powder. Both are about 60 % magnesium.
- Magnesium citrate, trimagnesium dicitrate
- All sold as “magnesium citrate”, but the versions differ. See below.
- Aspartate dihydrate, tetrahydrate
- “Di” and “tetra” mean two and four water molecules. More water, less magnesium: about 7.5 % and 6.7 %.
- Chloride hexahydrate
- The usual chloride in supplements. It’s about 12 % magnesium.
- “Magnesium (from …)”
- Gives only the magnesium. That’s the number to compare, but we can’t cross-check it.
Why citrate is the tricky one
“Magnesium citrate” can be any of three compounds, from about 11 % to 16 % magnesium.
- trimagnesium dicitrate, dry: about 16.2 %
- the same with water in its crystals (nonahydrate): about 11.9 %
- monomagnesium citrate, dry: about 11.3 %
So 500 mg could give 57 mg to 81 mg of magnesium, and labels rarely say which. We use 16.2 % as standard. If a product fits another version, its page says so.
Why it matters to you: compare citrates by the magnesium figure, not the compound weight. Otherwise you can be out by a third.
What this page doesn’t cover
This is chemistry only. We don’t judge whether one form works better or suits you. A pharmacist can talk it through.
Page text last revised 27 Oct 2026.