Stay hydrated with personalized water intake recommendations. This calculator considers your body weight, physical activity level, and climate to estimate how much water you need daily. General guideline: about 35ml per kg of body weight, adjusted for activity and heat.
The old 'eight glasses a day' rule is a rough estimate — actual water needs vary significantly based on body weight, activity level, climate, and diet. A common evidence-based guideline is 30-35 ml per kg of body weight for sedentary adults, increasing with exercise and heat exposure. A 70 kg person needs about 2.1-2.5 liters minimum; a 90 kg person exercising in heat might need 4+ liters. This calculator personalizes the recommendation based on your specific factors. Remember that about 20% of daily water intake comes from food (fruits, vegetables, soups), and beverages like tea and coffee count toward hydration despite mild diuretic effects.
Yes — despite being a mild diuretic, coffee and tea provide net hydration. A 2014 study in PLOS ONE found that moderate coffee consumption (3-6 cups/day) is as hydrating as water. Only very high caffeine doses cause significant fluid loss.
The simplest indicator is urine color: pale yellow means well-hydrated, dark yellow means drink more, clear means you might be overhydrating. Other signs of dehydration: thirst, dry mouth, headache, fatigue, and decreased urine output.
Yes — hyponatremia (water intoxication) occurs when excessive water dilutes blood sodium to dangerous levels. This is rare and mostly affects endurance athletes drinking large amounts without electrolytes. For most people, kidneys can process about 0.8-1 liter per hour.
Significantly. You lose 0.5-2 liters per hour of exercise through sweat, depending on intensity and temperature. Weigh yourself before and after exercise — each kg lost equals about 1 liter of fluid to replace. Add electrolytes for sessions over 60 minutes.
Absorption rate is similar. Cold water may slightly increase calorie burn (body warms it). Warm water may aid digestion. Room temperature is absorbed marginally faster. Choose whatever temperature makes you drink more — consistency matters most.