How much water should I drink per day?
The classic "8 glasses" rule is outdated. Daily water needs vary significantly based on body weight, activity level, climate, and individual physiology. Our calculator uses a research-backed formula: approximately 35 mL per kg of body weight for sedentary adults, scaled up for activity and climate. Most adults need between 2–3.5 liters per day from all sources.
Does coffee or tea count toward daily water intake?
Yes. Despite their mild diuretic effect, caffeinated beverages still contribute positively to your fluid balance for most people. However, for simplicity, our calculator focuses on plain water intake targets. Think of coffee and other beverages as bonus hydration on top of your water goal.
Do I need more water when exercising?
Yes, significantly. You can lose 0.5–2 liters per hour through sweat during intense exercise. Our calculator accounts for activity level in your baseline needs, but during specific exercise sessions, drink an additional 400–600 mL (14–20 oz) for every hour of moderate-intensity activity.
What are signs of dehydration?
Early signs include thirst, darker urine (aim for pale yellow), fatigue, mild headache, and reduced concentration. More severe dehydration causes dizziness, rapid heartbeat, and confusion. A good daily habit: check your urine color. Pale yellow = well hydrated. Dark yellow or amber = drink more water now.
Does the 20% from food figure apply to everyone?
The 20% figure is an average estimate from dietary surveys. People who eat lots of fruits and vegetables (which are 70–95% water) may get 30–40% of their hydration from food. People who eat mostly processed foods get much less. The actual percentage varies significantly based on diet.
