Water Intake Calculator
Estimate how much water to drink per day based on your weight and activity.
Inputs
Daily Water (liters)
2.87
Cups (8 oz)
12.0
Fluid Ounces
97
Step by step
Base water from body weight: 35 ml/kg
35 × 70.00
= 2,450 ml
Convert exercise duration to hours
30 min ÷ 60
= 0.500 h
Exercise adjustment: 12 ml/kg per hour
12 × 70.00 × 0.500
= 420 ml
Total daily water
2,450 + 420
= 2.87 L (12.0 cups / 97 fl oz)
How it works
This uses the common guideline of about 35 ml of water per kilogram of body weight, plus extra to replace fluids lost during exercise. Hot climates and illness increase needs further.
Formula
Daily water intake
Water (ml) = 35 × weight (kg) + 12 × weight (kg) × exercise (hours)
- 12
- Exercise top-up: 12 ml per kg per hour of activity
- 35
- Base requirement: 35 ml per kg of body weight
- W
- Total daily water in millilitres
- w_kg
- Body weight in kilograms
- t_h
- Daily exercise duration in hours
This is an estimate and not medical advice. Individual hydration needs vary with health, climate, and activity level. Consult a healthcare professional if you have concerns about fluid intake.
Frequently Asked Questions
Does other fluid count?
Yes — water in tea, coffee, milk, and water-rich foods all contribute to hydration, though plain water is the best primary source.
Can I drink too much water?
Rarely, but drinking extreme amounts in a short time can dangerously dilute blood sodium. Spread intake through the day and listen to your thirst.