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Water Intake Calculator
Daily water intake based on weight
Daily Water Intake
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Millilitres
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Glasses (250ml)
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Litres
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What is a Water Intake Calculator?
Estimates recommended daily water intake based on body weight and activity level. Proper hydration supports metabolism and cognitive performance.
How It Works
Base water (litres) = Body weight(kg) x 0.033. Add 350-500 ml per 30 minutes of exercise. Add 500-750 ml in hot conditions.
Example
70 kg person, 45 min daily exercise: Base = 70 x 0.033 = 2.31 L + exercise 700 ml = approx 3 L/day = 12 glasses.
Pro Tips
- Drink a glass of water immediately on waking - you lose 400-500 ml overnight through breathing.
- Urine colour is the best hydration indicator: pale yellow = hydrated; dark yellow = dehydrated.
- Coffee and tea count towards hydration despite mild diuretic effect (net hydration is positive).
- Electrolytes (sodium, potassium) are as important as water volume during intense exercise.
FAQ
How much water per day?▼
General guideline: 8 glasses (2 L). More precisely: 30-35 ml per kg of body weight.
Does coffee count?▼
Yes - net hydration is positive despite mild diuretic effect. Tea and coffee count approximately 80%.
Can you drink too much water?▼
Yes - hyponatremia (water intoxication) from large rapid intake is rare but dangerous.
Signs of dehydration?▼
Dark urine, dry mouth, headache, dizziness, fatigue. Even 1-2% dehydration impairs cognition.