Water Intake Calculator
Find out how much water you need to drink each day based on your body, activity, and environment.
Last updated: January 2026
Water Intake Calculator
How much water do you need?
A common recommendation is 8 glasses (64 oz / 1.9 L) per day, but individual needs vary. Your water requirement depends on your body weight, how active you are, and the climate you live in. A more accurate formula: weight (kg) × 30-40 mL per kg, adjusted for activity and heat.
This calculator uses your weight as the base and adjusts for activity level (more activity = more water lost through sweat) and climate (hot climates increase fluid needs). It shows results in both ounces and milliliters for convenience.
Signs of dehydration
Dark urine, dry mouth, fatigue, headache, dizziness, and reduced urine output are common signs of dehydration. If you're thirsty, you're already mildly dehydrated. Drink water throughout the day rather than chugging large amounts at once. The hourly schedule helps you spread your intake evenly.
For informational purposes only. Consult a healthcare professional.