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Stay properly hydrated with our water intake calculator. Based on your weight, activity level, and environmental factors, get personalized recommendations for optimal daily water consumption.
pounds
Additional hydration needed during exercise
15.0
cups (8 oz each)
3.55 L
120 oz • 3549 ml
0.9 cups
(8 oz per hour while awake)
Spread intake throughout the day for best hydration
Proper hydration is fundamental to health, affecting energy levels, cognitive function, physical performance, and virtually every bodily process. Yet individual water needs vary dramatically based on body size, activity level, climate, and special circumstances. Our calculator provides personalized recommendations using evidence-based formulas that account for all these factors.
The often-cited "8 glasses daily" is oversimplified. A more accurate baseline is 0.5 ounces per pound of body weight. A 150-pound person needs about 75 ounces (9 cups) as a baseline. But this is just the starting point—we then adjust for activity level (active people need 30-50% more), climate (hot weather increases needs significantly), exercise duration, and special conditions like pregnancy and breastfeeding.
Urine color is the easiest indicator—pale yellow indicates good hydration; dark yellow suggests you need more water. Other signs of proper hydration include consistent energy levels, clear thinking, healthy skin, and regular digestion. Dehydration symptoms include headaches, fatigue, dry mouth, decreased urination, dizziness, and dark urine. Even mild dehydration (1-2% body weight) impairs physical and mental performance.
Our calculator provides a practical drinking schedule spread throughout your waking hours—drinking the entire daily amount at once isn't effective. Start your day with water, drink between meals, and increase intake before, during, and after exercise. Remember that food provides about 20% of daily water intake, especially fruits and vegetables. While individual needs vary, meeting these personalized targets supports optimal health, performance, and well-being.
Yes. Overhydration (hyponatremia) occurs when excessive water dilutes blood sodium levels. This is rare in healthy adults but can occur in endurance athletes drinking excessively without electrolyte replacement. Symptoms include nausea, headache, confusion. Follow thirst cues and don't force excessive intake.
Yes, despite being mild diuretics, coffee and tea provide net hydration. The fluid consumed exceeds the mild diuretic effect. Water is ideal, but tea, coffee, milk, and water-rich foods (fruits, vegetables) all contribute to daily hydration. Limit sugary drinks and excessive caffeine.
For exercise under 60 minutes, water is sufficient. For longer or intense sessions, especially in heat, sports drinks provide beneficial electrolytes (sodium, potassium) and carbohydrates. Alternatively, eat salty snacks and fruit with water. Most people don't need sports drinks for typical workouts.