Nutrition
Hydration Calculator
Calculate your daily water needs based on your weight, activity level and climate.
Total daily water
— L
Base
—
ml
Glasses (250ml)
—
vasos
Bottles (500ml)
—
botellas
Why is hydration important?
Water accounts for 60% of body weight and is essential for thermoregulation, nutrient transport, digestion and cognitive performance. A 2% dehydration already reduces physical performance by 10–20%.
How is it calculated?
The base is 35 ml per kg of body weight. Adjustments are added for physical activity (up to +1000 ml) and climate (up to +500 ml on hot days).
Formula
Water (ml) = 35 × weight(kg) + activity adjustment + climate adjustment⚠️ Limitations
These are estimates. Actual needs vary with individual sweating, diet (fruits and vegetables provide water) and health status.
FAQ
How much water should I drink per day?
Most adults need 2–3.5 litres per day, including water from food.
Can I hydrate with sports drinks?
Yes, but they are only necessary for efforts lasting more than 60–90 minutes or in very hot conditions.
How do I know if I am well hydrated?
Urine colour is the best indicator: very pale yellow = well hydrated; dark yellow = drink more.
Can you drink too much water?
Yes, hyponatraemia from excess water is real but rare. Under normal conditions, the kidneys regulate excess efficiently.