Potassium mmol/L to mEq/L Converter
Convert potassium between mmol/L, mEq/L and mg/dL in one click. For potassium, 1 mmol/L is exactly 1 mEq/L.
Convert Potassium Units
Enter a potassium value, choose the units, and see every equivalent at once with a general range for context. This tool converts units only and is not medical advice.
Potassium Unit Converter
Millimoles per litre to milliequivalents per litre, and mg/dL.
Understanding the Conversion
Why mmol/L and mEq/L are the same for potassium
mmol/L to mEq/L
No change. mEq/L equals mmol/L multiplied by the ion’s charge, and potassium’s charge is 1. So 4.2 mmol/L is 4.2 mEq/L.
mmol/L to mg/dL
Multiply by 3.91. This comes from potassium’s atomic weight of about 39.1 g/mol. For example, 4.0 mmol/L × 3.91 = 15.6 mg/dL.
mg/dL to mmol/L
Divide by 3.91. For example, 19.5 mg/dL ÷ 3.91 = 4.99 mmol/L, which is about 5.0 mmol/L.
Check Your Lab’s Range
Reference ranges differ slightly between laboratories. Use the range printed on your own result, and ask your clinician what it means for you.
Potassium Unit Conversion Chart
Common serum potassium values in all three units, with a general range for each. Ranges are a guide only, and individual labs and clinicians may use different cut-offs.
| mmol/L | mEq/L | mg/dL | General Range |
|---|---|---|---|
| 2.5 | 2.5 | 9.8 | Low (seek medical advice) |
| 3.0 | 3.0 | 11.7 | Low |
| 3.5 | 3.5 | 13.7 | Normal (lower end) |
| 4.0 | 4.0 | 15.6 | Normal |
| 4.5 | 4.5 | 17.6 | Normal |
| 5.0 | 5.0 | 19.5 | Normal (upper end) |
| 5.5 | 5.5 | 21.5 | High |
| 6.0 | 6.0 | 23.5 | High (seek medical advice) |
| 6.5 | 6.5 | 25.4 | High (seek medical advice) |
Potassium Converter FAQ
Answers to the most frequently asked questions about converting potassium from mmol/L to mEq/L.
For potassium the two units are numerically the same, so 1 mmol/L equals 1 mEq/L. A potassium result of 4.2 mmol/L is therefore 4.2 mEq/L, and no calculation is needed.
Milliequivalents equal millimoles multiplied by the ion’s charge. Potassium (K+) has a charge of one, so the two units match. Ions with a charge of two, such as calcium and magnesium, are different: 1 mmol/L equals 2 mEq/L.
Divide the value in mg/dL by 3.91 to get mmol/L. This uses potassium’s atomic weight of about 39.1. For example, 15.6 mg/dL is about 4.0 mmol/L. To go the other way, multiply mmol/L by 3.91.
Many UK laboratories use a reference range of about 3.5 to 5.0 mmol/L (the same as 3.5 to 5.0 mEq/L). Exact ranges vary between labs, so check the range printed on your result and ask your GP or clinician what your result means.
It can be. Levels well outside the normal range can affect the heart and muscles. If you have a result that is very low or very high, or you have symptoms such as palpitations, weakness or collapse, seek medical advice promptly. In an emergency call 999 in the UK.