Water Intake Calculator
Estimate a reasonable daily water intake target based on your body weight, activity level, and climate.
How much water do you need?
Daily water needs vary by body size, activity level, and climate. A commonly used starting point is about 35 milliliters of water per kilogram of body weight per day, with additional water recommended to replace fluid lost through sweat during exercise or in hot, humid conditions.
How this calculator works
Enter your body weight, how much exercise you typically do per day, and whether you live in or are currently in a hot/humid climate. The calculator starts from the base 35 ml/kg guideline, adds roughly 350 ml for every 30 minutes of exercise (to replace sweat losses), and adds an extra 10% for hot or humid conditions where sweating increases. The result is shown in liters, ounces, and standard 8-ounce cups.
This is a general estimate, not a precise medical requirement — factors like diet, pregnancy, illness, and medications can change your actual needs. Water from food and other beverages also counts toward hydration. This tool is for general wellness planning and educational purposes only.