How to use the Water Intake Calculator
- Enter your body weight.
- Enter how many minutes you exercise on a typical day.
- Tell us if you live in a hot climate.
- See your daily goal in litres and glasses.
How the estimate works
A common guideline is about 35 ml of water per kg of body weight per day, plus around 350 ml for every 30 minutes of exercise and an extra 0.5 litre in hot weather. Part of your intake also comes from food, tea, milk and fruit.
Signs you need more water
- Dark yellow urine (aim for pale straw colour).
- Thirst, dry mouth, headache or tiredness.
- Dizziness after exercise or in the heat.
People with kidney, heart or liver conditions may need to limit fluids — follow your doctor’s advice.
Frequently asked questions
Is 8 glasses a day right for everyone?
It is a rough rule of thumb. Larger and more active people need more; smaller people and those in cool climates may need less.
Can I drink too much water?
Yes. Drinking very large amounts quickly can dangerously lower sodium levels. Spread your intake through the day.