Daily Hydration Goal (Climate) Calculator

About this calculator

Baseline daily water needs are commonly estimated from body weight — a widely used rule of thumb is roughly 30-35 mL per kilogram of body weight — and that baseline is then adjusted upward for heat, since higher ambient temperature and humidity increase sweat loss well beyond what's lost through normal insensible perspiration and urination alone.

People living in or traveling to hot climates, outdoor workers, and anyone adjusting their routine for a heatwave use a climate-adjusted hydration goal because a flat, weather-blind number understates needs on hot days and can contribute to dehydration, while sedentary cool-weather needs are lower than what's often quoted as a universal eight-glasses-a-day target.

This calculator takes your body weight and the ambient temperature, and returns an estimated daily water intake goal adjusted for how hot the conditions are.