The “8 glasses a day” (approximately 2 litres) is a general guideline but is not scientifically precise for everyone. Your actual needs depend on your weight, activity level, climate, health status, and diet. This calculator provides a more personalized estimate based on your individual factors.

Yes. Drinking excessively large amounts of water in a short period can cause hyponatremia (low blood sodium), a potentially dangerous condition. This is rare in healthy people with normal fluid intake. For most people, the body naturally signals thirst and regulates fluid balance. The recommended amount from this calculator represents a healthy daily target spread throughout the day.

Yes, partially. Despite their mild diuretic effect, caffeinated drinks like coffee and tea still contribute to your overall fluid intake. Research shows that moderate coffee consumption (up to 4 cups/day) contributes to hydration. However, plain water remains the optimal hydration source and should form the majority of your daily fluid intake.

Yes. During exercise you lose water through sweat and breath. A general guideline is to drink 500ml (about 2 cups) of water 2 hours before exercise, sip water every 15–20 minutes during exercise, and drink water after exercise to rehydrate. For intense exercise lasting over an hour, consider an electrolyte drink to replace lost sodium.

Common signs of mild dehydration include dark yellow urine, dry mouth, headache, fatigue, reduced concentration, and dizziness. A simple self-check: your urine should be pale yellow to clear. Dark yellow or amber urine is a reliable sign that you need to drink more water. Severe dehydration requires immediate medical attention.