Water Intake Calculator
Find your recommended daily water intake in liters, fluid ounces, and cups based on your weight and activity level.
Water Needs by Activity Level
| Activity Level | Multiplier | Example (75 kg) |
|---|---|---|
| Sedentary | ×1.0 | 2.6 L / 88 oz |
| Light | ×1.1 | 2.9 L / 97 oz |
| Moderate | ×1.2 | 3.2 L / 106 oz |
| Active | ×1.35 | 3.5 L / 119 oz |
| Very Active | ×1.5 | 3.9 L / 132 oz |
Frequently Asked Questions
How much water should I drink per day?
The commonly cited '8 glasses a day' rule is a rough guideline, not science. The National Academies recommends about 3.7 liters/day for men and 2.7 liters/day for women from all sources (food and beverages). Individual needs vary significantly with body weight, activity, climate, and health status. This calculator provides a personalized estimate based on your weight and activity level.
Does coffee or tea count toward water intake?
Yes — caffeinated beverages contribute to hydration. The mild diuretic effect of caffeine is not enough to offset the water content of a cup of coffee or tea. However, water, herbal teas, and low-sugar beverages are the best hydration sources. Alcohol has a net dehydrating effect and should not be counted.
What are signs of dehydration?
Early signs of dehydration include dark yellow urine, thirst, dry mouth, and reduced energy. Moderate dehydration causes headaches, dizziness, and reduced concentration. Even 1–2% body weight loss from dehydration measurably impairs physical and cognitive performance. Pale yellow urine is a reliable indicator of good hydration.
Should I drink more water when exercising?
Yes. During exercise, aim for 500–750 ml (17–25 oz) of water per hour of moderate activity in moderate temperatures. For intense or prolonged exercise (over 60 minutes), electrolyte replacement (sodium, potassium) becomes important to prevent hyponatremia (low sodium from over-drinking plain water).
Does food contribute to water intake?
Yes — about 20% of daily water intake comes from food, especially fruits and vegetables. Cucumbers, celery, strawberries, and watermelon are over 90% water by weight. This calculator estimates your total beverage intake need; food moisture is a bonus on top of that.