Daily water needs vary by body size, activity level, climate, and overall health, so any calculator can only offer a general starting estimate. This tool uses a common baseline of 33 mL per kilogram of body weight, plus an allowance for exercise.
The formula
For a 70 kg person doing 30 minutes of exercise: base = 70 × 0.033 = 2.31 L, plus 0.35 L for the exercise, totaling about 2.7 L.
Factors this estimate doesn't capture
- Climate and altitude: hot, humid, or high-altitude environments increase fluid needs beyond this baseline.
- Diet: water-rich foods (fruits, vegetables, soups) contribute meaningfully to total hydration, separate from drinking water alone.
- Individual health conditions: some medical conditions and medications affect fluid needs — follow a healthcare provider's specific guidance if you have one.
Signs of adequate hydration
Urine that's pale yellow, infrequent thirst, and stable energy levels are commonly cited practical indicators of adequate hydration, often more useful day-to-day than hitting an exact liter target.
This tool provides a general estimate for informational purposes and is not medical advice.
Frequently asked questions
How much water should I drink per day?
A common baseline is about 33 mL per kilogram of body weight, adjusted upward for exercise, heat, and other factors that increase fluid loss.
Does this include water from food?
No, this estimate is for water and other beverages. Water-rich foods like fruits and vegetables also contribute meaningfully to total daily hydration.
Are there signs I'm not drinking enough water?
Dark urine, persistent thirst, and fatigue are commonly cited practical signs of inadequate hydration, though individual needs vary.