Home » Water Intake CalculatorWater Intake CalculatorWater Intake CalculatorFast, Accurate and Simple Weight (kg): Age: Activity: Sedentary (0 min)Light (15 min extra)Moderate (30 min extra)High (60 min extra) Climate: NormalHot (+200 ml)Very Hot (+400 ml) Calculate Formula: Water (ml) = Weight (kg) × 35 + activity & climate adjustments. For guidance only. Consult a doctor if in doubt.