Water Intake Calculator

A common starting point is about 35 ml of water per kilogram of body weight, so a 70 kg adult lands near 2.45 liters. This tool uses that baseline and adds water for exercise. Treat it as a guide, not a hard rule.

Yes. Sweat increases your needs, so this tool adds about 350 ml for every 30 minutes of activity. Hot or humid weather, high altitude, fever, pregnancy and breastfeeding all raise your needs further, so drink to thirst on top of the estimate.

Dark yellow urine, thirst, dry mouth, headache, tiredness and dizziness are common signs. Pale, straw-colored urine usually means you are well hydrated. If you rarely feel thirsty and your urine is light, you are likely drinking enough.

The 8x8 rule, eight 8 oz glasses, is about 1.9 liters and is easy to remember but not based on strong evidence. Real needs vary with body size, activity, climate and diet, which is why a weight-based estimate is more personal.

Yes. Water in tea, coffee, milk, juice and foods like fruit, vegetables and soup all count toward your daily fluids. Plain water is just the simplest, calorie-free way to top up.

Rarely, but it is possible. Drinking very large amounts in a short time can dilute blood sodium, a condition called hyponatremia. Spread your intake across the day and let thirst guide you rather than forcing large volumes at once.