Water Intake Calculator

The general guideline is 0.5 oz per pound of body weight, or about 2–3 liters for most adults. The "8 glasses a day" rule (64 oz) is a rough approximation. Actual needs depend on body weight, activity level, climate, and diet.

Yes. Despite being mildly diuretic, caffeinated beverages still contribute to hydration. Studies show coffee and tea contribute net fluid to daily intake. Water from food (fruits, vegetables, soups) also counts — food provides about 20% of daily fluid needs.

Mild dehydration: thirst, dark yellow urine, reduced performance. Moderate: headache, dizziness, fatigue, dry mouth. Severe (5%+ body water loss): confusion, rapid heartbeat, no urine output. The best indicator is urine color — pale yellow is ideal.

Yes — hyponatremia (water intoxication) dilutes blood sodium, causing nausea, headaches, and in severe cases, seizures. This is most common in endurance events when athletes drink large amounts without electrolytes. For normal daily activity, this risk is very low.

Significantly. You lose 0.5–2 liters per hour of exercise through sweat, depending on intensity and temperature. Add 500ml for every hour of moderate exercise, more in heat or for intense workouts. Check urine color after exercise to gauge if you rehydrated adequately.