How much water should I drink each day?

A common guideline is about 8 cups (64 ounces or roughly 2 liters) of water per day, often called the "8x8 rule." However, the National Academies of Sciences recommends about 3.7 liters (125 oz) total daily water for men and 2.7 liters (91 oz) for women, which includes water from all beverages and food. Your actual needs vary based on your body size, activity level, climate, and health status. A practical indicator is urine color — pale yellow generally means you're well hydrated. If you exercise heavily or live in a hot climate, you'll need significantly more. Most healthy people can simply drink when thirsty and meet their needs.