Type the magnesium result from your blood test and pick the unit beside it. You get it in mmol/L, mg/dL and mEq/L, and where it sits against the range the NIH calls normal and the range MedlinePlus prints — in their words. Your lab’s own range, and your doctor, have the last word.
2 mg/dL is
Inside ODS’s normal range 2 mg/dL = 0.82 mmol/L = 1.65 mEq/L
| Line | mmol/L | mg/dL | mEq/L |
|---|
This is not medical advice and it does not diagnose anything. It shows where a number sits against published ranges; what your result means for you depends on your lab’s method, your other results, your history and your doctor.
NIH’s Office of Dietary Supplements: “Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles/liter(mmol/L)” — 1.82 to 2.31 mg/dL — and “Hypomagnesemia is defined as a serum magnesium level less than 0.75 mmol/L.” MedlinePlus prints a lab’s range of 1.7 to 2.2 mg/dL (0.70 to 0.91 mmol/L). To convert, 1 mmol/L is 2.43 mg/dL and 2 mEq/L.
How to use it
Find “Magnesium” on your blood test, type the number and pick the unit printed beside it: mg/dL on most US reports, mmol/L on most others, mEq/L on some. You get it in all three units, the band it falls in against NIH ODS’s lines, and whether it is inside MedlinePlus’s range — where the two ranges disagree, the page says so. Switching the unit converts the number you typed. It does not tell you what to take: that is the conversation with your doctor.
The lines, and the one conversion
NIH ODS (Magnesium fact sheet, updated January 6, 2026) gives the normal range and the hypomagnesemia line, and adds that toxicity “usually develop[s] after serum concentrations exceed 1.74 to 2.61 mmol/L”. MedlinePlus (review date 2/13/2025): “The normal range for blood magnesium level is 1.7 to 2.2 mg/dL (0.70 to 0.91 mmol/L)”, and “Normal value ranges may vary slightly among different labs.” Converting needs only magnesium itself: its atomic weight is 24.305, so 1 mmol/L is 2.4305 mg/dL, and the magnesium ion carries two charges, so 1 mmol/L is 2 mEq/L. MedlinePlus’s own pair — 1.7 mg/dL is 0.70 mmol/L — is the same factor.
| Result | mmol/L | mEq/L | NIH ODS | MedlinePlus range |
|---|---|---|---|---|
| 1.5 mg/dL | 0.62 | 1.23 | Under its normal range | Under |
| 1.7 mg/dL | 0.7 | 1.4 | Under its normal range | Inside |
| 1.9 mg/dL | 0.78 | 1.56 | Inside its normal range | Inside |
| 2 mg/dL | 0.82 | 1.65 | Inside its normal range | Inside |
| 2.2 mg/dL | 0.91 | 1.81 | Inside its normal range | Inside |
| 2.3 mg/dL | 0.95 | 1.89 | Inside its normal range | Over |
| 2.5 mg/dL | 1.03 | 2.06 | Above its normal range | Over |
| 4.5 mg/dL | 1.85 | 3.7 | Past its toxicity line | Over |
Worked examples
- 2.0 mg/dL (the page’s example) is 0.82 mmol/L and 1.65 mEq/L — inside both ODS’s range and MedlinePlus’s.
- 1.75 mg/dL is 0.72 mmol/L: under ODS’s 0.75 line but inside MedlinePlus’s 1.7 to 2.2. That is where the two ranges disagree, and the page says so rather than choosing.
- A UK result of 0.93 mmol/L is 2.26 mg/dL: inside ODS’s range, just over MedlinePlus’s 2.2.
- 2.0 typed as mmol/L would be 4.86 mg/dL — past ODS’s toxicity line — so the page asks you to check the unit: 2.0 mg/dL is 0.82 mmol/L.
Common mistakes
- Mixing the units. 2.0 mg/dL and 2.0 mmol/L are very different results; the unit is printed next to the number.
- Reading a normal result as “enough magnesium”. NIH ODS: serum levels “have little correlation with total body magnesium levels or concentrations in specific tissues”.
- Using this page’s range instead of your lab’s. Labs print their own, and MedlinePlus says they vary.
- Treating a number yourself. Whether to take magnesium is your doctor’s call — especially with kidney problems, where the body clears less of it.
Frequently asked questions
What is a normal magnesium level?
NIH ODS: “Normal serum magnesium concentrations range between 0.75 and 0.95 millimoles/liter(mmol/L)” — 1.82 to 2.31 mg/dL. MedlinePlus prints 1.7 to 2.2 mg/dL (0.70 to 0.91 mmol/L). Your lab’s own range is the one your doctor uses.
What is the magnesium normal range in mg/dL?
MedlinePlus: 1.7 to 2.2 mg/dL. NIH ODS’s 0.75 to 0.95 mmol/L is 1.82 to 2.31 mg/dL. The two overlap from 1.82 to 2.2 mg/dL.
How do I convert magnesium from mmol/L to mg/dL?
Multiply mmol/L by 2.4305 (magnesium’s atomic weight over 10) to get mg/dL, and by 2 to get mEq/L. 0.85 mmol/L is 2.07 mg/dL and 1.7 mEq/L.
What magnesium level is too low?
NIH ODS: “Hypomagnesemia is defined as a serum magnesium level less than 0.75 mmol/L” (1.82 mg/dL). A low result is a conversation with your doctor, who will read it with your other results.
What magnesium level is too high?
Above ODS’s normal range is anything over 0.95 mmol/L (2.31 mg/dL). ODS says signs of toxicity usually develop after serum concentrations “exceed 1.74 to 2.61 mmol/L” — a result like that is a prompt call to your doctor.
Does a normal blood test mean my magnesium is fine?
Not necessarily. NIH ODS: less than 1% of the body’s magnesium is in the serum, and serum levels “have little correlation with total body magnesium levels”. Your doctor may look at more than one number.
Read next
- The Magnesium Form Finder and the Magnesium Gummies Calculator — the intake side of the same mineral.
- 14 herbs, nootropics and supplements for rumination
- Nootropics for mitochondria: which work?
- Great vitamins for autumn depression
- The best 2 nootropics for social anxiety
This is not medical advice, and nothing here diagnoses or treats anything. It shows where a number sits against published ranges; what it means for you is a conversation with your doctor, who knows your lab’s method and your history. Some links on this site are affiliate links: I buy what I review at full price, and a commission never changes a verdict.