Calculate your ideal daily water intake based on weight, activity level, climate, and health conditions. Based on EFSA and NAS guidelines.
Based on National Academies of Sciences (NAS) and EFSA guidelines:
The National Academies of Sciences recommends about 3.7 litres/day total water for men and 2.7 litres/day for women — from all sources including food. The general rule is 35 ml per kg of body weight. Your actual needs vary based on activity, climate, and health conditions.
Yes, caffeinated drinks like coffee and tea do contribute to your daily fluid intake. Despite their mild diuretic effect, studies show they are net hydrating. However, water, milk, and herbal teas are the best sources of hydration. Sugary drinks and alcohol do not count.
Yes. Drinking extremely large amounts of water in a short time can cause hyponatremia (low blood sodium), which is dangerous. However, this is rare in everyday situations. For most people, drinking when thirsty and aiming for pale yellow urine is sufficient.
Signs of mild dehydration include dark yellow urine, dry mouth, headache, fatigue, and difficulty concentrating. Severe dehydration causes dizziness, rapid heartbeat, and confusion. The simplest check is urine colour — aim for pale straw yellow, not dark.
Yes. Larger bodies have more cells and produce more metabolic waste, requiring more water for optimal function. A person weighing 90 kg needs significantly more water than someone weighing 60 kg. This calculator uses 35 ml per kg as the baseline, adjusted for activity and climate.