Estimate how much water to drink per day from your body weight and exercise, shown in litres, millilitres, cups and ounces.
Estimates total daily water from about 33 ml per kg of body weight, plus roughly 350 ml for every 30 minutes of exercise. Food provides some water too. Needs rise in heat, at altitude, and during illness or pregnancy. This is a general guide, not medical advice.
A common starting estimate is about 33 ml per kilogram of body weight, which is roughly 2.5 litres for a 75 kg person, plus extra for exercise. The old 'eight glasses' rule is just a rough version of this.
Yes. Most drinks count toward hydration, and food (especially fruit and vegetables) provides a meaningful share too. The figure here is total water; you do not need to drink all of it as plain water.
Hot weather, high altitude, intense or long exercise, illness with fever, and pregnancy or breastfeeding all raise your needs. Thirst and pale-yellow urine are simple day-to-day guides.