# Corrected Calcium Calculator

URL: https://speedycalculator.com/calculators/health/corrected-calcium/
Last updated: 2026-10-25

> The corrected calcium calculator adjusts a total serum calcium result for a low albumin level, using the Payne formula. It estimates what the calcium would be if albumin were normal.

## Inputs

- Total calcium (mg/dL)
- Albumin (g/dL)
- Normal albumin (g/dL)

## Results

- Corrected calcium
- Corrected calcium (mmol/L)

## Formula

```
Corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL)
```

## Explanation

About 40% of calcium in blood is bound to albumin. When albumin is low, total calcium looks falsely low even if the active (ionised) calcium is normal.

### How to use the Corrected Calcium Calculator

- **Total calcium**
- **Albumin**
- **Normal albumin**

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

### How it works

For every 1 g/dL that albumin is below 4.0, 0.8 mg/dL is added to the measured calcium.

### Inputs explained

FieldWhat to enterTotal calciumIn mg/dLAlbuminIn g/dLNormal albuminIn g/dL

### What each result means

- **Corrected calcium** = [Total calcium] + 0.8×([Normal albumin] - [Albumin])
- **Corrected calcium (mmol/L)** = [Corrected calcium] ÷ 4.008

### Example values

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

Total calcium (mg/dL)Corrected calcium (mg/dL)4.14.96.156.958.2910.2511.0512.313.116.417.2
*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 — Total calcium: 8.2 mg/dL; Albumin: 3 g/dL; Normal albumin: 4 g/dL.

Results — **Corrected calcium = 9 mg/dL**; Corrected calcium (mmol/L) = 2.25 mmol/L.

## FAQ

**Is corrected calcium always reliable?**
It is an approximation; measuring ionised calcium directly is more accurate.

**How do I convert units?**
Divide mg/dL by 4.008 for mmol/L.

**What formula does the Corrected Calcium Calculator use?**
Corrected Ca (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL).


## Sources

- [Payne RB et al. Interpretation of serum calcium in patients with abnormal serum proteins. BMJ, 1973](https://pubmed.ncbi.nlm.nih.gov/4758544/)