About the Water Intake Calculator
Your water needs depend on your body weight, how much you sweat during exercise and the weather. This calculator gives a practical daily target in litres and 250 ml glasses.
How to use the Water Intake Calculator
- Enter your weight.
- Add your daily exercise minutes.
- Choose hot / humid if you live or work in the heat.
- Spread the glasses through the day and drink more when thirsty.
Formula used
Water (litres) ≈ weight (kg) × 0.035 + 0.35 L for every 30 minutes of exercise + 0.5 L in hot weather.
Frequently asked questions
How many glasses of water should I drink a day?
Most adults need about 8–12 glasses (2–3 litres) depending on body size, activity and climate. Food and other drinks also count.
Can I drink too much water?
Yes, very large amounts in a short time can be harmful. Spread intake through the day and follow your doctor’s advice if you have heart or kidney conditions.
What are signs of dehydration?
Dark yellow urine, thirst, headache, tiredness and dizziness are common signs.
Last reviewed: November 7, 2026