💧 Water Intake Calculator

How Much Water Should You Actually Drink Per Day?

The widely cited "8 glasses a day" rule is a rough estimate, not a personalised recommendation. A more accurate approach is to base intake on body weight. The commonly used guideline is approximately 35 ml of water per kilogram of body weight for a sedentary adult. So a 70 kg person needs roughly 2.45 litres per day from all sources, including food and beverages other than water.

Activity level significantly increases water needs. During moderate exercise, you can lose 0.5–1.0 litres of sweat per hour. In 's climate — especially in inland summer — that number can be higher. Active people should add approximately 0.5–1.0 litres per hour of moderate exercise to their baseline recommendation. A 70 kg person who exercises for an hour would therefore target closer to 3.0–3.5 litres on that day.

Climate and environment matter. Heat, humidity, and altitude all increase fluid loss through sweating and respiration. People living in hot regions or at altitude should drink on the higher end of any recommendation. Air conditioning and office environments can also cause mild dehydration because the air is dry, even if you don't feel hot.

Urine colour is the most practical indicator of hydration status. Pale straw yellow indicates adequate hydration. Dark yellow or amber indicates mild to moderate dehydration. If you're consistently producing very dark urine — especially in the morning — you're likely not drinking enough throughout the day. Clear, colourless urine can indicate overhydration, which is less common but is possible in endurance athletes who drink large volumes during exercise.

Thirst is not a reliable early indicator of dehydration — by the time you feel thirsty, you're already slightly dehydrated. Drinking water at regular intervals throughout the day (rather than in large volumes infrequently) helps maintain hydration more effectively.