Water Intake Calculator
Find how much water you should drink daily based on your weight and exercise — in liters, cups and ounces.
How much water should you drink?
The Water Intake Calculator estimates how much water you should drink each day based on your body weight and how much you exercise. It shows the result in liters, 8-ounce cups, and fluid ounces, so you can track it however you prefer. Everything is calculated in your browser, instantly.
Why hydration matters
Water is essential for almost every function in your body — regulating temperature, transporting nutrients, cushioning joints, and removing waste. Even mild dehydration can cause fatigue, headaches, poor concentration, and reduced physical performance. Drinking enough throughout the day keeps your body and mind working at their best.
How the estimate works
A common guideline is about 35 ml of water per kilogram of body weight per day. On top of that, exercise increases your needs, so the calculator adds roughly 350 ml for every 30 minutes of activity to replace what you lose through sweat. The result is a practical daily target rather than a rigid rule.
How to use it
- Enter your weight in kilograms.
- Add your typical daily exercise in minutes.
- Read your target in liters, cups, and ounces.
Factors that change your needs
| Factor | Effect |
|---|---|
| Hot or humid weather | Increases water loss through sweat |
| Exercise intensity | More sweat means more replacement needed |
| Illness (fever, vomiting) | Raises fluid requirements |
| Pregnancy/breastfeeding | Increases daily needs |
Tips to stay hydrated
- Start the day with a glass of water.
- Keep a reusable bottle nearby as a visual reminder.
- Drink before, during, and after exercise.
- Remember that fruits, vegetables, and other drinks also contribute.
Private and free
All calculations run in your browser. Nothing is uploaded, and the tool is completely free. This is general guidance, not medical advice — consult a professional for specific health concerns.
Frequently asked questions
How much water should I drink per day?
A common guideline is about 35 ml per kilogram of body weight, plus extra for exercise. This tool calculates your personal target.
Does coffee or tea count?
Most fluids contribute to hydration, and water-rich foods help too, though plain water is the best primary source.
Do I need more water when exercising?
Yes. The calculator adds roughly 350 ml per 30 minutes of activity to replace fluids lost through sweat.
Is this medical advice?
No. It is a general estimate. Consult a healthcare professional for specific medical or hydration concerns.