What Is Elemental Magnesium? The Only Label Number That Matters
Every magnesium label carries two numbers — the vehicle and the cargo — and the industry headline is nearly always the vehicle. One minute of conversion maths permanently reorganises the shelf. Here is the complete decode.
At a glance
- Elemental = the actual magnesium — compound weight is packaging
- The worked example: 1500mg bisglycinate (20%) → 300mg elemental — the Futuro Labs serving
- UK NRV: 375mg elemental/day from all sources
- Real dose = elemental × absorption — which retires oxide's big numbers
The one number the label hopes you won't find
Every magnesium supplement is a delivery vehicle: magnesium bonded to a carrier — glycine, citric acid, oxygen — and the carrier is most of the weight. "Elemental magnesium" names the cargo alone, and it is the only number on which two products can be compared, dosed against the 375mg UK NRV, or judged against the research. The industry's oldest trick is printing the vehicle's weight in headline type: "1500mg magnesium!" reads five times stronger than "300mg elemental", and on most labels the smaller true number is buried, footnoted, or absent. Learning the conversion takes one minute and permanently changes how the shelf looks.
The conversion table — memorise two rows, bookmark the rest
| Form | ~Elemental % | 1000mg compound gives | Absorption / notes |
|---|---|---|---|
| Bisglycinate (glycinate) | 14-20% | 140-200mg | Good; gentle — the daily default |
| Citrate | ~16% | 160mg | Good; mildly laxative |
| Malate | ~15% | 150mg | Good; daytime favourite |
| Taurate | ~9% | 90mg | Niche pairing with taurine |
| L-threonate | ~8% | 80mg | Costly; early-stage brain research |
| Oxide | ~60% | 600mg on paper | Poor absorption; laxative — paper champion only |
Two rows do most of the work: bisglycinate, because it's what you should usually buy, and oxide, because its 60% is the paper trap — elemental density without absorption is a big number that never arrives. Delivered magnesium is elemental × absorption, the equation that decides glycinate vs oxide in one line.
The worked example, straight off a real label
Futuro Labs Magnesium Glycinate prints the whole sum: 1500mg of magnesium bisglycinate (a 20%-elemental material) per two-capsule serving, providing 300mg elemental magnesium — 80% of the 375mg NRV — at £19.99 for 90 days, 22p a day. That both-numbers-stated format is itself a quality screen: brands confident in their elemental dose print it, and brands hiding behind compound weight have usually done the maths and preferred you didn't. Apply the test to any product in the UK rankings; the shortlist writes itself.
Futuro Labs Magnesium Glycinate
£19.99 for 90-day supply (180 capsules) · ~22p per day
Pros
- 300mg elemental magnesium per serving — 80% NRV
- Bisglycinate (glycinate) form — gentle, well absorbed
- Authorised claims: fatigue reduction, muscle function, psychological function
- 90-day supply £19.99 (~22p/day); 90-cap pouch £9.99
- Delayed-release vegan capsules, UK made
Cons
- Two capsules per serving
- Glycinate costs more per mg than oxide (for good reason)
Available from: Amazon UK — £19.99
NRV, RDA and where 375mg comes from
The reference number deserves its own decode. NRV — Nutrient Reference Value — is the UK/EU labelling standard, set at 375mg elemental magnesium daily for adults, and it is the denominator behind every percentage on a UK tub: Futuro Labs' 300mg elemental is printed as 80% NRV. You'll also meet RDA (the older term NRV replaced), and separate government intake guidance that varies by age and sex around the same ballpark. Two habits keep it simple: read every percentage as a share of 375mg elemental, and remember food is contributing too — which is why a supplement at 80% NRV comfortably closes the typical UK gap without stacking to the ceiling.
Frequently asked questions
What is elemental magnesium?
The actual magnesium content of a supplement, separate from whatever it's bonded to. '1500mg magnesium bisglycinate' is compound weight; the elemental magnesium inside it is 300mg — the number your body uses and the only number that lets you compare products. UK NRV is 375mg elemental from all sources.
How do I calculate elemental magnesium from a label?
Multiply compound weight by the form's elemental percentage: bisglycinate ~14-20% (Futuro Labs' material is 20%: 1500mg → 300mg), citrate ~16%, malate ~15%, taurate ~9%, L-threonate ~8%, oxide ~60% (but poorly absorbed). If a label states only a compound number, apply the percentage; if it states neither clearly, don't buy it.
Is more elemental magnesium always better?
No — delivered magnesium is elemental dose times absorption, which is how 300mg elemental from bisglycinate beats bigger oxide numbers. And above ~400mg supplemental elemental daily, digestive upset arrives without extra benefit. The sweet spot for most adults is a stated 200-300mg elemental from a well-absorbed form.
Prefer labels that do the maths for you?
Futuro Labs Magnesium Glycinate — 1500mg bisglycinate, 300mg elemental, both stated. £19.99.
Shop on Amazon UK