Water Intake Calculator
How much water should you actually drink? It depends on your weight, how active you are, and where you live. Enter those and get a personalized daily target in litres and glasses.
How to use
- Enter your body weight in kg or lbs.
- Pick your activity level for the day.
- Select your climate. Hot or humid weather means you need more.
- Hit Calculate to see your recommended daily intake in litres and glasses.
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Adequate hydration is essential for every bodily function, from regulating temperature and flushing toxins to transporting nutrients and lubricating joints. The commonly cited '8 glasses a day' rule is a rough guideline; actual needs vary based on body weight, activity level, climate, and health conditions. A more personalised estimate is 35 ml per kg of body weight per day.
Physical activity significantly increases water needs. For every hour of moderate exercise, you lose an additional 500–1,000 ml of water through sweat. Hot and humid climates further increase requirements. Coffee, tea, and most beverages (except alcohol) count toward your daily intake, as does water content in fruits and vegetables.
Frequently Asked Questions
How much water should I drink per day?
A common guideline is 35 ml per kg of body weight. For a 70 kg person, that is about 2.45 litres (roughly 8–10 glasses). Active individuals and those in hot climates may need up to 3–4 litres per day.
Does drinking more water help with weight loss?
Yes, to an extent. Drinking water before meals reduces calorie intake. It also boosts metabolism temporarily and helps distinguish thirst from hunger. However, water alone is not a weight loss solution. It works best as part of a balanced diet.
What are the signs of dehydration?
Early signs include thirst, dark yellow urine, dry mouth, and fatigue. Moderate dehydration causes headaches, dizziness, and reduced concentration. Severe dehydration is a medical emergency. A simple way to check: urine should be pale yellow, not dark.
Can you drink too much water?
Yes. Overhydration (hyponatremia) dilutes sodium in the blood, causing nausea, headaches, and in extreme cases, seizures. It is rare in healthy adults with normal kidney function but can occur in endurance athletes who drink excessively. Stick to thirst cues and the recommended 2–3.5 litres per day for most people.