How much water should you drink a day?
A common evidence-based guideline is about 30–35 ml of water per kilogram of body weight, adjusted up for exercise and hot weather. This calculator uses ~35 ml/kg and adds extra for activity and climate.
Signs you may need more water
- Dark yellow urine (pale straw is the goal)
- Headaches, tiredness or difficulty concentrating
- Feeling thirsty — a sign you're already slightly dehydrated
Does tea or coffee count?
Yes. Despite the myth, moderate caffeinated drinks still count toward your fluid intake for most people.
Can you drink too much water?
Rarely, but yes — drinking extreme amounts in a short time can dilute blood sodium. Spread intake across the day.