Water Intake Calculator
It's easy to under-drink when you're busy — steady hydration through the day matters.
Your details
About this water intake calculator
Daily water needs depend on body weight, activity, climate, and health conditions. A common rule is about half your body weight in ounces — but exercise and heat raise requirements.
Older adults often feel thirst less sharply, which makes planned hydration important. Mild dehydration can affect energy, focus, and digestion.
Enter your weight and activity level below for a personalized daily water target in cups and liters.
Frequently asked questions
How much water should I drink per day? +
Many adults need 8–12 cups (2–3 liters) daily. Heavier or more active people need more. This calculator adjusts for weight and activity level.
Does coffee count toward water intake? +
Moderate coffee and tea contribute to fluid intake for most healthy adults, though water remains the best baseline hydrator.
What are signs of dehydration? +
Dark urine, dry mouth, headache, dizziness, and fatigue can signal dehydration. Seek medical care for severe symptoms.
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