Understanding your hydration needs
Water needs scale roughly with body size, and rise further with sweat losses from exercise and hot or humid weather. This calculator combines a simple weight-based baseline with adjustments for activity and climate to give a practical daily target.
The baseline formula
Baseline intake is about 33 ml of water per kilogram of body weight per day.
Exercise adjustment
Add roughly 0.35 liters for every 30 minutes of exercise to replace sweat losses.
Climate adjustment
A hot or humid climate adds about 10% to the total to account for extra fluid loss.
How is daily water intake calculated?
This calculator uses a common guideline of about 33 ml of water per kilogram of body weight per day, then adds extra water for exercise and hot or humid climates.
Does exercise increase how much water I need?
Yes. This tool adds roughly 0.35 liters of water for every 30 minutes of exercise to help replace fluid lost through sweat.
Should I drink more water in hot weather?
In hot or humid conditions your body loses more fluid through sweat, so this calculator adds about 10% to your baseline recommendation when you select that option.
Is this water intake calculator medical advice?
No. It provides a general guideline only. Individual needs vary with health conditions, medications and pregnancy, so speak with a doctor for personal advice.
Try another free calculator: BMI Calculator, BMR Calculator, or Calorie Calculator. Browse all online tools.