Water Intake Calculator

Weight Unit

Body WeightEnter a valid weight.

Activity Level

Recommended Daily Water Intake

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How to Use This Tool

Enter your body weight and unit.
Select your activity level.
Click Calculate for your recommended daily water intake.

The Water Intake Formula

Base Water Need (mL) = Body Weight (kg) × 35

This baseline is then adjusted upward for higher activity levels or hot climates, which increase fluid loss through sweat.

Why 35mL Per Kilogram?

This is a commonly cited general guideline for adult daily water needs from plain water and other fluids combined. Individual needs vary based on climate, health conditions, pregnancy/breastfeeding status, and diet (foods with high water content, like fruits and vegetables, also contribute to hydration).

Signs You May Need More Water

Dark yellow urine (pale yellow generally indicates good hydration)
Persistent thirst, fatigue, or headaches
Exercising, especially in heat, or being at altitude

Important Note

This is a general wellness estimate, not medical advice. Certain health conditions (kidney disease, heart failure) require specific fluid intake guidance from a healthcare provider, which may differ from this general calculation.

Frequently Asked Questions

Does this include water from food?

This estimate focuses on fluid intake from drinking. Foods with high water content (fruits, vegetables, soups) also contribute meaningfully to total hydration, so your actual drinking needs might be somewhat lower if your diet is water-rich.

Should I drink more water when exercising?

Yes, exercise increases fluid loss through sweat, which is why this calculator applies a higher multiplier for more active lifestyles — you may need additional water directly around intense or prolonged exercise sessions.

This calculator is provided for general informational and estimation purposes only. Results should not be treated as professional financial, tax, legal, medical, or engineering advice. Always verify critical calculations with a qualified professional or official source before making decisions.