Daily Water Intake Calculator
Recommended daily water intake based on body weight and activity.
Enter body weight and activity level. Get recommended daily water intake in ounces, cups, milliliters, and liters.
The "rule of thumb" this calculator uses
A common practitioner-recommended baseline is half your body weight in pounds, consumed in fluid ounces per day. For example, a 160-pound person should drink about 80 oz of water daily as a baseline. We then add 12 oz for moderate exercise and 24 oz for heavy exercise, since you lose extra water through sweat.
The official recommendations
The US National Academies of Sciences, Engineering, and Medicine recommends 15.5 cups (3.7 liters) of fluids per day for men and 11.5 cups (2.7 liters) for women, including water from food and beverages. That includes ALL fluids, not just water. About 20 percent of daily fluid intake typically comes from food.
When to drink more
- Hot or humid weather: add 16-32 oz beyond baseline
- High altitude: dry air increases water loss
- Pregnancy or breastfeeding: follow your doctor's specific guidance
- Fever, vomiting, or diarrhea: rehydration is critical (sports drinks may help replace electrolytes)
- Strenuous exercise over an hour: consider electrolyte replacement, not just water
Can you drink too much water?
Yes. Drinking very large amounts of water in a short time can cause hyponatremia (dangerously low sodium). This is rare in everyday life but is a real risk for endurance athletes and people drinking water competitively. Sip throughout the day rather than chugging gallons.
Informational only. This calculator is not medical advice and does not diagnose, treat, or prevent any condition. Always consult a qualified healthcare provider for medical decisions.