Electrolyte Calculator

Enter your weight, age, exercise duration, and activity intensity to calculate your personalized electrolyte replacement needs. The Electrolyte Calculator returns your recommended daily fluid intake, sodium, potassium, and magnesium targets, plus the number of electrolyte servings needed to stay optimally hydrated during training.

Disclaimer: This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making any health-related decisions.

years
min

Total minutes of physical activity per day

Hot and humid conditions increase sweat and electrolyte losses

Results

Total Daily Fluid Intake

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Electrolyte Servings Needed

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Sodium Target

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Potassium Target

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Magnesium Target

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Estimated Sweat Loss

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Frequently Asked Questions

When should I drink electrolytes?

Electrolytes are most important before, during, and after exercise lasting more than 45–60 minutes. For shorter workouts, water alone is usually sufficient. In hot climates or during high-intensity sessions, starting electrolyte intake early in your workout helps prevent cramping and dehydration.

How do I calculate my sweat rate?

Weigh yourself (in kg) before and after a 60-minute workout without drinking fluids. Every 1 kg lost equals approximately 1 litre of sweat. This calculator estimates your sweat rate based on your body weight, exercise intensity, duration, and climate.

Why does sodium matter more than water for hydration?

Sodium is the primary electrolyte lost in sweat and it regulates fluid balance inside and outside your cells. Drinking plain water without replacing sodium can actually dilute blood sodium levels — a condition called hyponatremia — which can cause nausea, headaches, or in severe cases, serious health issues.

What electrolytes do I lose when I sweat?

Sweat contains primarily sodium (the most abundant), along with potassium, magnesium, calcium, and chloride. The amounts lost vary by individual, intensity, and environment. Sodium and potassium are typically the most critical to replace after intense exercise.

How does activity intensity affect my electrolyte needs?

Higher-intensity exercise like HIIT or endurance training dramatically increases sweat rate — often 1–2 litres per hour compared to 0.3–0.5 litres during light activity. This means proportionally more sodium, potassium, and magnesium are lost and need to be replaced to maintain performance and avoid muscle cramps.

Does climate affect how many electrolytes I need?

Yes, significantly. In hot or humid conditions, your body sweats more to cool itself, which accelerates electrolyte losses. Athletes training in temperatures above 25°C (77°F) may need 50–100% more electrolyte replacement than those exercising in cooler environments.

How does this fit into my training plan?

Use this calculator daily or before key training sessions to plan your hydration strategy. On rest days, your fluid and electrolyte needs drop considerably, so adjust accordingly. For multi-day events or back-to-back training sessions, consistent electrolyte replenishment between sessions is especially important for recovery.

Can I get enough electrolytes from food alone?

For light or moderate exercisers, a balanced diet with foods like bananas, leafy greens, nuts, and lightly salted meals can cover most electrolyte needs. However, during intense or prolonged exercise lasting over 90 minutes — especially in heat — dedicated electrolyte drinks or supplements are generally more practical and reliable.