Water Intake Calculator
How much water you need each day depends mainly on your body weight and how much you exercise. As a guide, you need roughly 35 ml of water per kilogram of body weight, plus extra for activity. This calculator estimates your daily water target in litres and cups.
Water Intake Calculator
How your daily water need is estimated
The calculator starts from about 35 ml of water per kilogram of body weight, then adds extra for exercise — roughly 350 ml for every 30 minutes of activity. The total is your suggested daily intake, shown in litres and in cups.
Good to know
Your needs rise in hot weather, at altitude, and when you are ill. Drinks and water-rich foods all count toward the total, so listen to your thirst as well.
Frequently asked questions
How much water should I drink a day?
A common guide is about 35 ml per kilogram of body weight, so a 70 kg person needs roughly 2.5 litres, with more on active or hot days.
Does exercise increase how much water I need?
Yes. You lose water through sweat, so add roughly 350-500 ml for every 30 minutes of exercise to stay hydrated.
Do other drinks and food count?
Yes. Other drinks and water-rich foods contribute to your total intake, so you do not need to drink the whole amount as plain water.
What are signs of dehydration?
Dark urine, thirst, tiredness, headache and dizziness can all signal that you need to drink more water.
Can I drink too much water?
Very rarely, drinking far more than you need can dilute body salts. For almost everyone, the bigger risk is drinking too little.