Water Intake Calculator
Estimate a practical daily fluid range from bodyweight, exercise duration, and climate context. Results update as you change an input.
How much water do you need?
There is no single requirement for everyone. This tool starts with a broad 30–35 mL/kg/day range and adds an exercise-related range.
Bodyweight and hydration
Bodyweight offers a simple starting point, but diet, illness, pregnancy, medications, and individual physiology also affect fluid needs.
Hydration during exercise
The exercise addition uses approximately 0.4–0.8 liters per hour. Sweat rate, duration, intensity, clothing, and conditions can move needs outside that range.
Hot weather
Hot conditions may increase sweat losses. The calculator does not automatically prescribe a precise climate addition; use the displayed total as a starting point.
Does coffee count toward fluid intake?
Common caffeinated drinks contribute fluid. Individual tolerance and total caffeine intake still matter.
Water vs electrolyte drinks
Water is often sufficient for shorter sessions. Prolonged exercise, heavy sweating, or high heat may require attention to sodium and other electrolytes from drinks or food.