Why water matters
Water makes up around 60% of an adult's body. It regulates temperature through sweat, carries nutrients, cushions joints, removes waste through the kidneys and keeps the brain working well. Even mild dehydration can cause headaches, tiredness, poor concentration and constipation. In hot climates like much of India, especially in summer, the body loses a lot of water through sweat, so needs are higher.
How to use the calculator
- Enter your body weight in kilograms.
- Enter how many minutes you exercise on a typical day.
- Choose the climate you spend most of your day in.
- Read your estimated daily intake in litres and in 250 ml glasses.
How the estimate is made
Base = body weight (kg) × 33 ml
Exercise = about 350 ml for every 30 minutes
Climate = +500 ml (hot or humid) or +750 ml (very hot)
Example: a 65 kg person who exercises for 30 minutes a day in a hot, humid city needs about 65 × 33 = 2,145 ml, plus 350 ml for exercise and 500 ml for climate: roughly 3.0 litres a day, or about 12 glasses.
For comparison, health authorities such as the European Food Safety Authority suggest a total daily water intake of about 2.0 litres for women and 2.5 litres for men in a temperate climate, from all drinks and food combined. About 20% of our water usually comes from food, especially fruit, vegetables, dal, curd and soups.
Signs you need more water
- Dark yellow urine. Pale straw colour usually means you are well hydrated.
- Thirst, dry mouth or lips.
- Headache, dizziness or unusual tiredness, especially in the heat.
Tips to drink enough
- Keep a bottle with you and refill it a set number of times each day.
- Drink a glass of water with every meal and before and after exercise.
- Buttermilk, coconut water, lemon water and herbal tea count towards your total; sugary drinks add unnecessary calories.
- For long, sweaty workouts or heat exposure, oral rehydration salts help replace lost salts as well as water.
Frequently asked questions
Is drinking too much water harmful?
Yes, drinking very large amounts quickly can dangerously lower blood sodium. Spread your intake through the day.
Do tea and coffee count?
Yes. Moderate amounts of tea and coffee add to your daily fluid intake.
Who should not follow this estimate?
People with kidney disease, heart failure or other conditions may need to limit fluids. Follow your doctor's advice.
General guidance only, not medical advice.