Hydration Calculator

Daily fluid need is approximated from weight, climate and activity sweat losses rather than the generic eight-glasses myth. The baseline multiplies kilos by roughly 33 ml, then adds about 350 ml per 30 minutes of moderate exercise and a climate addend for hot or humid environments; food moisture contributes roughly 20% of the displayed liters, so explicit drinking volume is slightly less. At 70 kg temperate and sedentary, the baseline sits near 2.3 liters, rising toward 3.0 liters with 45 minutes of daily exercise in warm weather.

Let thirst and pale-yellow urine be the ultimate referee — no formula beats hourly feedback from concentration and frequency. Spread intake through the day rather than loading it at once; extreme rapid intake can dilute serum sodium into hyponatremia, a rare but real risk the calculator's conservative ceilings are designed to avoid.