Find out exactly how much water you should drink every day with our free water intake calculator. Based on your weight, activity level, and climate, get a personalized daily hydration goal in cups, ounces, and liters.
Daily Water Intake Calculator
This is a general guideline. Individual needs vary. Listen to your body and consult a doctor if needed.
How Much Water Should You Drink?
The classic "8 glasses a day" rule is a rough guideline. Your actual needs depend on body weight, activity level, climate, and diet. A common medical approach uses 35 mL per kg of body weight as a baseline, then adjusts for activity and environment.
Daily Water Intake Examples
- 150 lb (68 kg) sedentary person: ~2.4 liters (81 oz, about 10 cups/day)
- 180 lb (82 kg) moderately active: ~3.4 liters (115 oz, about 14 cups/day)
- 200 lb (91 kg) athlete: ~4.2 liters (142 oz, about 18 cups/day)
Frequently Asked Questions
How much water should I drink per day?
The National Academies of Sciences recommends about 3.7 liters (125 oz) per day for men and 2.7 liters (91 oz) for women from all sources, including food. Actual needs vary based on activity, climate, and individual health.
Does coffee and tea count toward water intake?
Yes. Despite the myth that caffeine dehydrates you, research shows that moderate coffee and tea consumption counts toward your daily fluid intake. The mild diuretic effect of caffeine is outweighed by the fluid in the beverage.
What are signs of dehydration?
Common signs include dark yellow urine, dry mouth, fatigue, dizziness, and headache. A quick way to check hydration: your urine should be pale yellow. Dark yellow or amber means drink more water.
Can you drink too much water?
Yes. Overhydration (hyponatremia) can occur when you drink too much water too quickly, diluting sodium in your blood. This is rare in healthy people under normal conditions but can be a risk during extreme athletic events.
Does water intake help with weight loss?
Research suggests drinking water before meals can reduce calorie intake. Water has no calories and can temporarily boost metabolism. Staying well-hydrated also reduces fatigue, which can improve exercise performance and indirectly support weight management.