Water Intake Calculator

How this water intake calculator works

Your daily water need depends primarily on body weight, then adjusts for how active you are and the climate you live in. The baseline rule — half your body weight in ounces — is a widely used heuristic endorsed by dietitians for healthy adults.

The formula

Daily water (oz) = Body weight × 0.5 × Activity multiplier × Climate modifier

• Activity: Sedentary ×1.0, Light ×1.1, Moderate ×1.2, Very active ×1.3
• Climate: Temperate ×1.0, Hot ×1.1, Cold ×0.95

Factors that increase your water need

• Exercise lasting more than 30 minutes
• Hot or humid weather
• High altitude (above 8,200 ft)
• Pregnancy or breastfeeding
• Fever, vomiting, or diarrhea

Listen to your body — thirst is a reliable guide for most healthy adults. The calculated amount is a starting point, not a strict target.