About this calculator
Enter your weight, daily exercise and whether it is hot, as it is for much of the year in India.
How to use it
- Enter your weight.
- Enter minutes of exercise a day.
- Choose whether the weather is hot.
The formula
Water = weight × 35 ml + 350 ml per 30 minutes of exercise + 500 ml in hot weather
- 35 ml/kg
- base need
- extras
- for sweating during exercise and heat
Worked example
68 kg, 30 minutes of exercise
- Base = 68 × 35 = 2,380 ml.
- Exercise adds 350 ml.
- Total about 2.7 litres, or 11 glasses.
What the result means
Pale yellow urine is a simple sign you are drinking enough.
Assumptions
- Healthy adult.
Limitations
- Heart, kidney and liver conditions may need fluid limits; follow your doctor.
- Includes water from food, tea, milk and other drinks.
Frequently asked questions
How many litres of water a day?
Most adults need roughly 2 to 3 litres, more in heat or with exercise.
Do tea and milk count?
Yes, along with water in food.
Can I drink too much water?
Very large amounts in a short time can be dangerous; spread drinking through the day.
Not medical advice. This calculator is a general screening tool and cannot diagnose any condition. Results are estimates. Please talk to a doctor or a qualified health professional about your health and before making changes to diet, exercise or treatment.
Last reviewed on 1 October 2026. Found a mistake? Tell us.