# Corrected Magnesium Calculator

URL: https://speedycalculator.com/calculators/health/corrected-mg/
Last updated: 2026-10-30

> The corrected magnesium calculator adjusts serum magnesium for low albumin, since about a quarter of magnesium in the blood is bound to protein, and converts between mg/dL, mmol/L and mEq/L.

## Inputs

- Serum magnesium (mmol/L, mg/dL, mEq/L)
- Albumin (g/dL, g/L)

## Results

- Corrected magnesium

## Formula

```
Corrected Mg (mmol/L) = measured Mg + 0.005 × (40 − albumin g/L)
mg/dL = mmol/L × 2.431 · mEq/L = mmol/L × 2
```

## Explanation

Low albumin lowers total magnesium even when the free (ionised) magnesium is normal. Magnesium is essential for nerve, muscle and heart rhythm; low levels often accompany low potassium and calcium.

### How to use the Corrected Magnesium Calculator

- **Serum magnesium**
- **Albumin**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter serum magnesium and albumin.

### Inputs explained

FieldWhat to enterSerum magnesiumUnits: mmol/L, mg/dL, mEq/LAlbuminUnits: g/dL, g/L

### Example values

How the main result changes when **Serum magnesium** changes and everything else stays at the example values above:

Serum magnesium (mmol/L)Corrected magnesium (mmol/L)0.350.40.5250.580.70.750.8750.931.051.11.41.45
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Serum magnesium: 0.7 mmol/L; Albumin: 3 g/dL.

Results — **Corrected magnesium = 0.75 mmol/L**.

## Key terms

- **Hypomagnesaemia**: Low blood magnesium.

## FAQ

**What is a normal magnesium?**
About 0.7–1.05 mmol/L (1.7–2.6 mg/dL).

**What causes low magnesium?**
Diuretics, proton pump inhibitors, alcohol, diarrhoea and poor intake.

**Is correction always needed?**
It is a rough adjustment; ionised magnesium is rarely available.


## Sources

- [Kroll MH, Elin RJ. Relationships between magnesium and protein concentrations in serum. Clin Chem, 1985](https://pubmed.ncbi.nlm.nih.gov/3971571/)