How is this calculated?
This calculator uses the widely cited guideline of about 30ml per kg of body weight as a base recommendation, then adds extra fluid for exercise-related losses plus an additional amount for hot weather or extended time outdoors. For example, someone weighing 60kg who exercises at a moderate level would get 60Γ30=1,800ml plus 550ml, for a recommended total of about 2,350ml.
What counts toward this water intake?
The water intake referred to here is closer to total fluid intake β not just plain water, but also broth, moisture from fruits and vegetables, and fluid from other beverages. That said, caffeinated drinks and alcohol can have a diuretic effect and actually increase fluid loss, so it's better to meet most of your needs with plain water.
A note of caution
The figures this calculator provides are general reference guidelines β your ideal fluid intake can vary considerably depending on health conditions such as kidney disease or heart failure. If you have a kidney or heart-related condition, be sure to follow your doctor's guidance.
Frequently Asked Questions
Is "8 glasses of water a day" accurate?
"8 glasses a day (about 2 liters)" is a well-known rule of thumb, but the amount you actually need varies by body weight, activity level, climate, and health status. A calculation based on your body weight is generally considered more personalized than a one-size-fits-all number like 8 glasses.
Is it better to drink a lot at once, or spread it out?
Spreading your water intake out over the course of the day, rather than drinking a large amount all at once, is generally thought to help your body use fluids more efficiently.