Calcium conversion: mg/dL to mmol/L
For calcium, 1 mg/dL = 0.249513 mmol/L, and 1 mmol/L = 4.0078 mg/dL.
Common values
mg/dL to mmol/L
| mg/dL | mmol/L |
|---|---|
| 6 | 1.50 |
| 7 | 1.75 |
| 8 | 2.00 |
| 8.5 | 2.12 |
| 9 | 2.25 |
| 9.5 | 2.37 |
| 10 | 2.50 |
| 10.5 | 2.62 |
| 11 | 2.74 |
| 12 | 2.99 |
| 13 | 3.24 |
| 14 | 3.49 |
mmol/L to mg/dL
| mmol/L | mg/dL |
|---|---|
| 1 | 4.0 |
| 1.1 | 4.4 |
| 1.2 | 4.8 |
| 1.3 | 5.2 |
| 1.8 | 7.2 |
| 2 | 8.0 |
| 2.1 | 8.4 |
| 2.2 | 8.8 |
| 2.4 | 9.6 |
| 2.6 | 10.4 |
| 2.8 | 11.2 |
| 3 | 12.0 |
Each converted value is worked out in full and then rounded: mmol/L to two decimal places and mg/dL to one decimal place.
Source: molar masses summed from the IUPAC CIAAW abridged standard atomic weights, 2024.
The values are facts and free to use; this table’s selection and presentation are © 2026 ScienceQuest.
Why the factor is specific to calcium
Calcium, Ca, is a single atom, so its molar mass is its standard atomic weight, 40.078 g/mol. A result in mg/dL is a mass and one in mmol/L an amount of substance, so converting divides by the molar mass and multiplies by 10 for the decilitres in a litre: 1 mg/dL = 10 ÷ 40.078 = 0.249513 mmol/L.
A factor fits one analyte only: 1 mg/dL of glucose is 0.0555074 mmol/L, as the glucose conversion table shows.
Total and ionized calcium share the factor.
- mmol/L = mg/dL × 10 ÷ 40.078
- mg/dL = mmol/L × 40.078 ÷ 10
Which countries report which unit
American and Indian laboratories usually report calcium in mg/dL; British, Canadian and Australian ones report mmol/L.
Worked example
- 10 mg/dL in mmol/L
- = 10 × 10 ÷ 40.078
- = 2.49513 mmol/L