Dehydration Rate Calculator

Estimate hourly fluid loss from sweat during hiking based on temperature, exertion, body weight, and elevation. Stay ahead of dehydration.

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How It Works

At 1% body weight loss from dehydration, thirst appears. At 2%, performance drops 25%. At 5%, heat stroke risk is serious. At 10%, it is life-threatening. Drink 0.5-1 L per hour while hiking in heat. Pre-hydrate before activity. Electrolytes matter — plain water can cause hyponatremia (low sodium) in extreme cases. Urine should be pale yellow, not clear or dark.