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Products / Magnesium

Read a magnesium label in 30 seconds

Holding a bottle at the shelf? These five steps tell you how much magnesium you’re actually buying, and what it costs.

The five steps

  1. Find the magnesium figure in the panel, after “equivalent to” or “from”. Not the big number on the front.
  2. Check what it’s per: one tablet, one capsule, one scoop or two tablets.
  3. Name the compound: glycinate, citrate, oxide or aspartate. More than one means a blend.
  4. Check the maths if both figures are printed. The calculator below does it for you.
  5. Work out the cost per 100 mg: price ÷ serves in the pack ÷ magnesium per serve × 100.

The calculator page has a table of common amounts that works without JavaScript.

Why each step matters
  1. The magnesium figure is the only one you can compare. Look for “equivalent to”, “equiv.”, “from” or “elemental”.
  2. 150 mg per tablet and 150 mg per two tablets are very different buys.
  3. The compound sets how much is magnesium. “Amino acid chelate” with no amino acid named can’t be worked out. Which magnesium is which lists the names.
  4. Rough shares: oxide 0.60, citrate 0.11 to 0.16, glycinate 0.14, aspartate 0.075. Within about 15 % of the magnesium figure? The label adds up.
  5. Cost per 100 mg is the fair way to compare small doses with large ones.

A worked example

Here are the same steps on Blackmores Magmin 500mg, with today’s figures and price. It’s an example of the maths, not a pick.

Blackmores Magmin 500mg. The brand’s product page, read 27 Oct 2026, says “Magnesium aspartate dihydrate 500 mg, equivalent magnesium 37.4 mg” for a serve of 1 tablet.

  1. How much magnesium is in a serve? 37.4 mg per 1 tablet, says the brand’s product page. That’s the figure you’re given, so our costs use it.
  2. Does the label add up? 500 mg × 0.0749 = 37.5 mg The stated 37.4 mg is 0.1 % below that. That’s inside our 15 % margin, so the mark is adds up.
  3. What does the magnesium cost? The RRP at Chemist Warehouse, seen 27 Oct 2026, is $50.49 for 250 tablets. $50.49 ÷ 250 serves = 20.2c a tablet 20.2c ÷ 37.4 mg × 100 = $0.54 per 100 mg of magnesium A sale would lower both, while it lasts.

Full working and every source for this product

So the “500mg” on the front is the compound. The magnesium per tablet is much smaller, because aspartate is only about 7.5 % magnesium. Cost per 100 mg lets you compare it fairly.

The example uses the RRP or the regular shelf price. At the shelf, use the price you’d actually pay: the maths is the same.

Before you buy

Prices change and packs get reformulated, so the pack in your hand is what counts. Always read the label and follow the directions for use. Whether magnesium suits you, and how much, is a question for a pharmacist or doctor.

Page text last revised 27 Oct 2026.