This tool is part of these guided projects. Each project provides step-by-step instructions with checklists and all the tools you need in one place.
Understand your body metrics, set realistic goals, plan nutrition, and build a sustainable fitness routine.
Assess your fitness baseline, set a goal pace, build a training plan, and prepare nutrition, gear, and race-day strategy.
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A common guideline recommends 30–35 ml of water per kg of body weight daily as a baseline, adjusted for activity and climate.
Daily Water (ml) = Body Weight (kg) × 30–35Add 350–500 ml per 30 minutes of moderate exercise to replace sweat losses. Hot climates increase needs by 500–1,000 ml.
Total Intake = Base Intake + (Exercise Minutes ÷ 30 × 350 ml)The Water Intake Calculator uses peer-reviewed equations (WHO, Mifflin-St Jeor, Harris-Benedict, or domain-specific standards). Results are general wellness estimates, not medical diagnoses.
Metric = f(height, weight, age, activity, …)Updated: July 2026
Calculating baseline hydration for a desk worker with minimal physical activity.
→ ~2,100–2,450 ml/day (~8–10 cups)
A daily runner adjusting water intake for training sessions.
→ ~2,650 ml base + ~700 ml exercise = ~3,350 ml/day
A gym member records height and weight in the Water Intake Calculator to establish a baseline BMI and revisits monthly to track progress toward a goal.
The '8×8 rule' (2 liters) is a rough average. A 50kg person needs less; a 90kg athlete needs more. Scale intake to body weight and activity.
Caffeine has mild diuretic effects; sugary drinks add calories. Water-rich foods (fruits, soup) contribute ~20% of daily fluid intake — account for total hydration sources.
Use our free Water Intake Calculator for fast, accurate results in your browser. No signup or installation required — works on any device.