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About This Calculator
This calculator estimates how much water you should drink each day based on your body weight, daily activity, and climate. Staying properly hydrated supports energy, digestion, temperature regulation, and focus.
How It's Calculated
- Base need: ~35 ml of water per kg of body weight
- Activity: ~12 ml added per minute of exercise
- Hot or humid climates add a 10% adjustment
Needs vary by age, health, diet, and pregnancy. About 20% of daily fluids usually comes from food. If you're thirsty, drink — thirst is a reliable cue.
Frequently Asked Questions
How many liters of water should I drink a day?
Based on your inputs, about 2.81 L per day (roughly 12 cups). A common general guideline is about 2–3 liters for most adults, adjusted for size and activity.
Does coffee and tea count toward hydration?
Yes. While caffeine has a mild diuretic effect, the water content in coffee and tea still contributes to your daily fluid intake. Plain water remains the best choice, but other beverages count too.
Do I need more water when exercising?
Yes. The more you sweat, the more you need to replace. This calculator adds water for your exercise minutes — for intense or long sessions, add extra fluids before, during, and after.