How to Use the Muscle Cramp Electrolyte Calculator
Sudden leg cramps during exercise are often blamed on muscle fatigue alone, but low sodium, potassium, and magnesium — lost through sweat — are one of the main culprits. Drinking water alone doesn't replace those electrolytes, and in some cases can actually make cramping worse.
This calculator takes your exercise duration and how much you sweat (your sweat rate) and estimates your total fluid loss, along with how much sodium, potassium, and magnesium you should replace, plus a recommended fluid intake. The more you sweat and the longer you exercise, the more electrolytes you lose — so it's worth thinking about electrolyte replacement alongside plain water.
Keep in mind sweat electrolyte concentration varies a lot between individuals, so these numbers are estimates based on general averages. If you cramp frequently or have an underlying condition like kidney disease or hypertension, don't just load up on electrolytes — check with a doctor or dietitian to find the right intake for you.
Frequently Asked Questions
Muscle fatigue, dehydration, and low sodium, potassium, or magnesium are the most commonly cited causes. Cramps tend to happen more in hot, humid conditions or during long-duration exercise.
Sports drinks, electrolyte tablets, or foods (bananas for potassium, salt for sodium, nuts for magnesium) all work. For long workouts, a drink with electrolytes can help more than plain water alone.
These are estimates based on general guidelines, so individual needs vary. If you cramp frequently or have an underlying condition, adjust your intake with guidance from a professional.