Water Intake Calculator
Find out exactly how much water you should drink daily based on your weight, activity level, and climate.
Where the "8 Glasses a Day" Rule Came From
The often-cited "8 glasses a day" rule has shaky origins — it may trace back to a 1945 US Food and Nutrition Board recommendation that was taken out of context. The actual recommendation mentioned that most of this water comes from food. A 2002 review in the American Journal of Physiology found no scientific evidence supporting 8 glasses as a universal requirement.
Your actual needs depend on body weight, how much you sweat, the climate you live in, and even altitude. This calculator uses a weight-based formula (roughly 33ml per kg of body weight) adjusted for activity and climate — a more individualized approach.
Signs You're Not Drinking Enough
Dark yellow urine is the simplest indicator. Headaches, fatigue, and poor concentration are common signs too. For a deeper look, check out our article on 8 signs you're not drinking enough water.
⚠️ Medical Disclaimer
This tool provides estimates for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making health decisions. Results may vary based on individual factors not captured by this calculator.