Water Intake Calculator
Calculate your daily water intake needs
Calculator
How to Use
Calculate your daily water intake needs
Enter your weight
Input your body weight in kg or lbs
Select activity level
Choose your typical daily activity level
Add factors
Account for climate, exercise, and health conditions
Get recommendation
See your personalized daily water intake goal
Water Intake Formula
Base intake = Weight (lbs) × 0.5 to 1 oz OR Weight (kg) × 30-40 ml
Multiply your weight by the factor, then adjust for activity and climate.
Frequently Asked Questions
The general recommendation is 8 glasses (64 oz / 2 liters) per day, but actual needs vary. A better formula is 0.5-1 oz per pound of body weight. A 150 lb person needs 75-150 oz (2.2-4.4 liters). Adjust for exercise, climate, and health conditions.
Yes, coffee and tea do count towards hydration despite being mild diuretics. Studies show the fluid you gain outweighs the diuretic effect. However, water remains the best choice. Limit caffeine to 400mg/day.
Early signs include thirst, dark yellow urine, dry mouth, headache, and fatigue. Severe dehydration causes dizziness, rapid heartbeat, confusion, and very dark urine. Check urine color - pale yellow indicates good hydration.
Yes, overhydration (hyponatremia) is possible but rare. It dilutes sodium in your blood. Symptoms include nausea, headache, and confusion. Athletes and people with certain conditions are at higher risk. Drink when thirsty, don't force excess water.