Elemental magnesium is the weight of the magnesium itself, not of the compound it is bound to. The NIH says a US Supplement Facts panel declares the elemental amount, so 1,000 mg of magnesium bisglycinate, which is 14.1% magnesium, holds about 141 mg of elemental magnesium. Divide the elemental figure by 375 for the EU % NRV or by 420 for the US % DV: 200 mg is 53% of the NRV and 48% of the DV.
Images are AI-generated and illustrative.
We sell one magnesium product, Satiovex Tri-Mag Night, and use its label as the example below. Satiovex Tri-Mag Night is a three-form magnesium capsule: magnesium bisglycinate, magnesium L-threonate and magnesium taurate, 200 mg of elemental magnesium per serving of three capsules, 90 capsules, 30 servings.
What does elemental magnesium mean on a supplement label?
Supplement magnesium is bound to another substance, such as glycine, taurine, threonic acid, citric acid or oxygen, and the bound pair is the compound. The compound weighs more than the magnesium inside it, so one capsule has two weights: compound and elemental.
The NIH Office of Dietary Supplements (ODS) fact sheet for health professionals (updated 6 January 2026) says the Supplement Facts panel "declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound". The FDA's labelling guide for supplement makers gives the same rule with calcium as its example: list the weight of the calcium, not of the calcium carbonate that supplies it.
So "magnesium 200 mg" on a US panel means 200 mg of magnesium, and "magnesium (as magnesium bisglycinate) 200 mg" names the source in brackets, which the FDA guide allows, without changing the number. The EU rules for supplements (Directive 2002/46/EC) ask for the amount of each nutrient in the unit set for it, the milligram for magnesium. We read that as the magnesium itself, but we found no EU text that says "elemental", so treat that as our reading.
How do you convert compound weight to elemental weight?
Each compound holds a fixed share of magnesium: the atomic weight of magnesium, 24.305, divided by the molar mass of the compound, which is the sum of the atomic weights in its formula.
Take magnesium bisglycinate, C4H8MgN2O4. Its molar mass is 4 × 12.011 + 8 × 1.008 + 24.305 + 2 × 14.007 + 4 × 15.999 = 172.423 g/mol. The share is 24.305 ÷ 172.423 = 0.14096, or 14.1%. So 1,000 mg of the compound holds 1,000 × 0.14096 = 141 mg of magnesium, and 400 mg holds about 56 mg. In reverse, 200 mg of magnesium needs 200 ÷ 0.14096 = 1,419 mg of bisglycinate. The table repeats the sum for four more forms.
| Compound | Formula | Magnesium share | Compound weight for 200 mg of magnesium |
|---|---|---|---|
| Magnesium oxide | MgO | 60.3% | 332 mg |
| Trimagnesium dicitrate (anhydrous) | Mg3(C6H5O7)2 | 16.2% | 1,237 mg |
| Magnesium bisglycinate | C4H8MgN2O4 | 14.1% | 1,419 mg |
| Magnesium taurate | C4H12MgN2O6S2 | 8.9% | 2,243 mg |
| Magnesium L-threonate (anhydrous) | C8H14MgO10 | 8.3% | 2,423 mg |
These shares move with the hydration state and, for citrate, with which compound the word means. Our elemental magnesium percentage by form guide shows the working for twelve forms.
How do you read a magnesium supplement label, line by line?
| Panel line | What it tells you | What to check |
|---|---|---|
| Serving size | How many capsules the maker counts as one serving | Every amount below is per serving, not per capsule |
| Servings per container | How many servings the pack holds | Servings times capsules per serving gives the capsule count |
| Magnesium, in mg | The elemental magnesium in one serving | Use this figure to compare products |
| "as" or "from" | The compound or compounds that supply the magnesium | Which forms are named, and whether compound weights are given |
| % NRV or % DV | The elemental amount as a percentage of a reference value | Which reference value: 375 mg (EU) or 420 mg (US) |
| Other ingredients | Capsule shell, fillers and binders | A magnesium salt used as a binder is listed here, not as the nutrient |
| Directions and warnings | The serving the maker recommends, and cautions | Follow the pack and read the cautions |
What percentage of the NRV is 200 mg of magnesium?
In the EU, Annex XIII of Regulation (EU) No 1169/2011 lists the nutrient reference value (NRV) for magnesium as 375 mg. In the US, the FDA's Daily Value table (content current as of 5 March 2024) lists the Daily Value (DV) as 420 mg, and the ODS fact sheet gives it for adults and children aged 4 years and older.
The percentage is the elemental amount divided by the reference value. For 200 mg, 200 ÷ 375 = 0.5333, printed as 53% NRV, and 200 ÷ 420 = 0.4762, printed as 48% DV. The milligrams are identical; only the divisor changes.
| Elemental magnesium per serving | % of 375 mg NRV | % of 420 mg DV |
|---|---|---|
| 100 mg | 27% | 24% |
| 200 mg | 53% | 48% |
| 300 mg | 80% | 71% |
| 400 mg | 107% | 95% |
Serving or capsule: which number are you reading?
A panel states amounts per serving, and the maker's directions define the serving. The FDA's labelling guide says one serving "equals the maximum amount recommended, as appropriate, on the label for consumption per eating occasion". EU Directive 2002/46/EC ties declared amounts to "those per portion of the product as recommended for daily consumption on the labelling".
So a headline figure may describe one capsule, three capsules or a day's portion. Divide the elemental figure by the capsules in a serving before comparing products. For Satiovex Tri-Mag Night, 200 mg across three capsules averages 200 ÷ 3 = 66.7 mg per capsule.
The ceiling test: can that form hold that much magnesium?
Every compound has a maximum magnesium share, so a label can be checked against itself. Multiply the compound weight by the share to get the most magnesium that compound can hold. If the elemental figure is higher, some magnesium must come from another source in the blend.
Suppose a label (hypothetical numbers, for the arithmetic only) reads "magnesium (as magnesium bisglycinate) 200 mg" and states 1,000 mg of the compound per serving. The ceiling is 1,000 × 0.14096 = 141 mg. The claim is 59 mg above it, so a second source, such as magnesium oxide at 60.3% magnesium, would have to supply the difference. The test does not say the product is wrong; it says the label names one source where the arithmetic needs another, so ask the maker.
When no compound weight is printed, run it the other way: divide the elemental figure by the share to get the least compound the claim needs. 200 mg from bisglycinate alone needs at least 1,419 mg, and a stated weight below that floor does not add up.
Reading the Satiovex Tri-Mag Night label step by step
Here is the panel read with those steps, using only the label facts we hold for the panel on the Tri-Mag Night product page.
- Serving and pack. One serving is three capsules. A bottle holds 90 capsules, which is 30 servings.
- Magnesium. 200 mg of elemental magnesium per serving, or 66.7 mg per capsule on average, and 30 × 200 = 6,000 mg per bottle.
- Reference values. The page states 53% NRV, which is 200 ÷ 375. On the US basis the same 200 mg is 48% of the 420 mg DV.
- Forms. Magnesium bisglycinate, magnesium L-threonate and magnesium taurate. The product page lists no magnesium oxide and no magnesium citrate.
- Floor test. Bisglycinate is the richest of the three at 14.1%, so 200 mg needs at least 1,419 mg of compound per serving even if all of it came from bisglycinate, and more with threonate (8.3%) and taurate (8.9%) in the mix. If the panel prints compound weights, add them up: the total has to clear that floor.
- Warnings. The page's warnings include not exceeding the recommended daily dose, and consulting a doctor if you are pregnant, breastfeeding, have kidney problems or take medication. Read them in full on the page.
How do you compare two magnesium labels?
- Put both on one basis: elemental milligrams per serving.
- Divide by the capsules in a serving to get elemental milligrams per capsule.
- Read the forms named, and run the ceiling test on any compound weights printed.
- Check that both percentages use the same reference value, 375 mg or 420 mg.
- Calculate the price per 100 mg of elemental magnesium: price ÷ (servings × elemental mg per serving) × 100. The percentage-by-form guide shows it with our three pack prices.
- Read the directions and warnings on each pack.
If one product is a blend and the other a single form, our triple magnesium complex vs magnesium glycinate label check covers that pairing.
Questions about elemental magnesium on labels
Is elemental magnesium the same as magnesium glycinate?
No. Elemental magnesium is the mineral itself. Magnesium glycinate is a compound of magnesium and glycine, about 14.1% magnesium by weight, so 400 mg of it holds about 56 mg of elemental magnesium (400 × 0.14096 = 56.4). PubChem lists "magnesium glycinate" and "magnesium bisglycinate" as names for one record, formula C4H8MgN2O4. Our glycinate vs bisglycinate guide covers the two names.
What percentage of the NRV is 200 mg of magnesium?
53%, because 200 ÷ 375 = 0.533. Against the US Daily Value of 420 mg, the same 200 mg is 48%.
How can I tell whether a label shows compound or elemental weight?
Read the lines. "Magnesium 200 mg" or "magnesium (as ...) 200 mg" is the elemental amount under the ODS and FDA wording. A figure beside a compound name with no mention of magnesium is a compound weight until the maker says otherwise, and the share converts it. A blend total with no breakdown tells you neither, so ask for the elemental figure.
Who should ask a doctor or pharmacist before using a magnesium supplement?
Read the warnings on the pack you are considering. Ours include not exceeding the recommended daily dose, and consulting a doctor if you are pregnant, breastfeeding, have kidney problems or take medication. The ODS fact sheet lists several types of medicine that can interact with magnesium supplements and says people taking them regularly should discuss their magnesium intakes with their health care providers. The three-form capsule page prints the full label, and the FAQ covers delivery and returns.
How we checked this page
- Sources opened. On 10 October 2026 we read the ODS magnesium fact sheet (through an Internet Archive copy captured 7 October 2026, because NIH's server refused our automated request), the FDA Daily Value table and labelling guide, Regulation (EU) No 1169/2011 Annex XIII, Directive 2002/46/EC and PubChem. Molar masses are our arithmetic from the IUPAC abridged atomic weights and agree with PubChem to within 0.03 g/mol.
- What we could not find. An EU text that says "elemental", a regulator's table of magnesium share by compound, and an explanation of why the EU and US reference values differ.
- Review. No doctor, pharmacist or dietitian has reviewed this page.
- Who we are. Satiovex products are sold by Xinop LLC, trading as Satiovex. We run this site and have a financial interest in the products.
- Corrections. If something here is wrong, contact us and we will check it.
Last updated 10 October 2026 by the Satiovex editorial team.
Sources
- NIH Office of Dietary Supplements, Magnesium: Fact Sheet for Health Professionals (updated 6 January 2026).
- US Food and Drug Administration, Daily Value on the Nutrition and Supplement Facts Labels (content current as of 5 March 2024).
- US Food and Drug Administration, Dietary Supplement Labeling Guide: Chapter IV, Nutrition Labeling (April 2005, non-binding guidance).
- Regulation (EU) No 1169/2011 on food information to consumers, Annex XIII (EUR-Lex).
- Directive 2002/46/EC on food supplements, Article 8 and Annex I (original 2002 text, EUR-Lex).
- PubChem compound records: CID 84645, 14792, 13343447, 45489777 and 6099959.