function calculateMeq() {
var mg = document.getElementById('potassium_mg').value;
var resultArea = document.getElementById('potassium-result-area');
if (mg && mg > 0) {
// Formula: mEq = mg / atomic_weight
// Potassium atomic weight is approx 39.098
var mEq = parseFloat(mg) / 39.098;
resultArea.style.display = 'block';
resultArea.style.backgroundColor = '#e8f5e9';
resultArea.style.color = '#2e7d32';
resultArea.innerHTML = mg + ' mg is approximately ' + mEq.toFixed(2) + ' mEq of Potassium';
document.getElementById('potassium_meq').value = mEq.toFixed(2);
} else {
alert('Please enter a valid amount in milligrams.');
}
}
function calculateMg() {
var mEq = document.getElementById('potassium_meq').value;
var resultArea = document.getElementById('potassium-result-area');
if (mEq && mEq > 0) {
// Formula: mg = mEq * atomic_weight
var mg = parseFloat(mEq) * 39.098;
resultArea.style.display = 'block';
resultArea.style.backgroundColor = '#e3f2fd';
resultArea.style.color = '#1565c0';
resultArea.innerHTML = mEq + ' mEq is approximately ' + mg.toFixed(2) + ' mg of Potassium';
document.getElementById('potassium_mg').value = mg.toFixed(2);
} else {
alert('Please enter a valid amount in milliequivalents.');
}
}
function resetPotassiumCalc() {
document.getElementById('potassium_mg').value = ";
document.getElementById('potassium_meq').value = ";
document.getElementById('potassium-result-area').style.display = 'none';
}
Understanding Potassium Conversions: mg to mEq
In clinical practice, potassium is often measured in two different units: milligrams (mg) and milliequivalents (mEq). While nutrition labels typically list potassium content in milligrams, medical prescriptions for supplements like potassium chloride (KCl) are almost always written in milliequivalents.
The Conversion Formula
Potassium is a monovalent ion, meaning its valency is 1. The atomic weight of potassium (K) is approximately 39.1. To convert between these units, use the following formulas:
- mEq = mg / 39.1
- mg = mEq × 39.1
Common Reference Values
To help you contextualize your results, here are some common dosages and food values often encountered in clinical and nutritional settings:
| mEq Amount |
Approximate mg |
Common Source |
| 10 mEq |
391 mg |
Standard small supplement |
| 20 mEq |
782 mg |
Common clinical dose |
| 12 mEq |
470 mg |
One large banana |
| 40 mEq |
1,564 mg |
High-dose therapy |
Why This Conversion Matters
Managing potassium levels (kalemia) is critical for heart function and muscle performance. Hyperkalemia (too much potassium) or hypokalemia (too little potassium) can lead to life-threatening cardiac arrhythmias. When a doctor prescribes 40 mEq of potassium, they are asking for roughly 1,564 mg of elemental potassium. Knowing how to switch between these units ensures medication safety and dietary compliance.
Important Disclaimer: This calculator is for educational and informational purposes only. Do not adjust your medication or supplement intake without consulting a healthcare professional. Values are based on elemental potassium (K+).