Find out exactly how much water you should drink each day based on your weight and activity.
This tool estimates how much water you should drink daily based on your body weight, activity level, and climate. Proper hydration supports temperature regulation, joint lubrication, nutrient transport, and overall bodily function.
A common general guideline is roughly 30-35 ml of water per kilogram of body weight per day, adjusted upward for higher activity levels, hot climates, or increased sweating. Some approaches use body weight in pounds divided by 2 to estimate ounces needed.
Enter your body weight and activity level (and optionally climate conditions), and the calculator returns a suggested daily water intake target.
Example: A 70 kg person with moderate activity might have a baseline target of roughly 70 × 33 ≈ 2,310 ml (about 2.3 liters) per day, before adjusting for exercise or climate.
Does the "8 glasses a day" rule apply to everyone? That's a simplified general guideline, but actual needs vary significantly based on body size, activity level, climate, and diet (since food also contributes water), so individualized estimates like this calculator provide a more tailored reference point.
Does all fluid intake count toward hydration, not just plain water? Yes, other beverages and water-rich foods (like fruits and vegetables) also contribute to overall hydration, though plain water remains a straightforward and calorie-free primary source.
How does exercise change water needs? Physical activity increases fluid loss through sweat, so more intense or longer exercise sessions typically require additional water intake beyond baseline daily needs to stay properly hydrated.
What are signs of inadequate hydration? Common signs include dark yellow urine, thirst, fatigue, and dry mouth, though needs vary by individual, and severe dehydration warrants medical attention.
Can you drink too much water? Yes, though uncommon, drinking excessive amounts of water in a short period can dilute sodium levels in the blood (hyponatremia), so extremely high intake, especially during endurance events, should be balanced with electrolyte intake.