Electrolyte Loss Calculator
Estimate how much Sodium, Potassium, and Magnesium you lose during intense sweating.
ElectrolytesHydrationSweat LossCramping
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Estimated Sweat Loss / Hour
🧪 Homemade Electrolyte Mix (Saves Money!)
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1000 ml
Water
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1/2 tsp
Salt (Sodium)
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Lemon
Potassium
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Honey
Carbs (Energy)
*Mix these ingredients to match your hourly loss estimates.
Method and basis
How the figure above is derived, and when not to act on it.
Understanding Sweat Composition
Sweat is not "just water." It's a precise cocktail of electrolytes essential for nerve firing and muscle contraction. Losing too much without replacement leads to "cramping," "bonking," and cardiac drift.The Big 4: What Are You Losing?
1. Sodium (Na+)**: The MAIN driver. Sweat is salty. Range: **400-2000mg per liter. 2. Chloride (Cl-): Typically mirrors sodium loss. 3. Potassium (K+): Minor loss (~200mg/L). Found in cells, less critical to replace acutely. 4. Magnesium (Mg2+): Very minor loss (~20mg/L). Cramps are usually due to sodium or fatigue, not magnesium.💧 Electrolyte Loss in Sweat (per Liter)
| Electrolyte | Average Loss | Low Range | High Range (Salty Sweater) |
|---|---|---|---|
| Sodium (Na+)** | **1000 mg | 400 mg | 2000 mg |
| Chloride (Cl-)** | **900 mg | 350 mg | 1700 mg |
| Potassium (K+)** | **200 mg | 150 mg | 300 mg |
| Magnesium** | **20 mg | 10 mg | 30 mg |
⚠️ The Danger: Hyponatremia (Water Intoxication)
Drinking plain water during an ultra-event (>4 hours) without sodium dilutes your blood sodium levels. * Symptoms: Headache, bloating, confusion, seizure. * Rule: If you crave salt, eat salt. If you slosh when you run, stop drinking.💧 Hydration Protocol
Pre-Loading (Before)
Drink 500ml** with **500mg Sodium 60-90 minutes before the event to expand plasma volume.Maintenance (During)
* < 60 Mins: Water is fine. * 60-120 Mins: 100-200 calories (carbs) + 300mg Sodium. * > 2 Hours: 500-800mg Sodium per liter of fluid.Recovery (After)
Weigh yourself. For every 1lb (0.45kg)** lost, drink **20-24oz of fluid with electrolytes.WinSport Editorial & Research Standards
All formulas and reference values used in this tool are sourced from peer-reviewed scientific literature and validated clinical guidelines. Our research team continuously audits each calculator for accuracy and updates methodology as new evidence emerges.
Read the Science
Sports Science Articles- Drinking More Water During a Race Won't Fix This — And Sometimes Makes It WorseHyponatraemia — dangerously low blood sodium — is more common in endurance events than most athletes realise. And it's almost always caused by drinking too much plain water, not too little.5 min read
- Glycerol Hyperhydration: The Pre-Race Fluid Trick Most Athletes Have Never Heard OfGlycerol hyperhydration can expand plasma volume by 400–700 mL before heat racing. Here's the science behind this underused protocol and how to apply it safely.5 min read
- Athletes Who Train in Heat Gain a Physiological Advantage That Persists in Cool Conditions. Here's the Mechanism.Two weeks of exercise-heat exposure expands plasma volume by 10–12%, lowers core temperature onset threshold for sweating, and reduces heart rate at equivalent workloads. These adaptations improve performance in both hot and temperate conditions.5 min read
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