Water Intake Calculator — A common rule of thumb is 8 cups (about 2 L) per day, but the actual number varies with body size, activity, climate, and life stage. The most cited evidence-based model is 30-35 ml per kg of body weight, which scales to the person's size. Add a bonus for hot climate (+200-500 ml) and for pregnancy (+300 ml) or lactation (+700 ml).
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Estimates are general guidance for healthy adults, not medical advice. Needs vary with health conditions, medications, climate, and activity. Follow your thirst and your doctor's advice first.
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¿Qué es Water Intake Calculator?
A common rule of thumb is 8 cups (about 2 L) per day, but the actual number varies with body size, activity, climate, and life stage. The most cited evidence-based model is 30-35 ml per kg of body weight, which scales to the person's size. Add a bonus for hot climate (+200-500 ml) and for pregnancy (+300 ml) or lactation (+700 ml).
This calculator returns the result in four units so you can use whichever you prefer: litres, millilitres, US fluid ounces, and the 8-oz (240 ml) cup. The "baseline" is the body-weight × factor number; the adjustments are listed separately so you can see what each part contributes.
Cómo usarlo
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Enter your body weight
In kilograms. Convert from pounds by dividing by 2.205.
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Pick your activity level
Be honest. A desk job is "sedentary"; a construction worker is "very active".
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Pick your climate
Most people are "temperate". If you live in a hot or humid place, use "hot".
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Set pregnancy or lactation
Adds 300 ml/day for pregnancy, 700 ml/day for lactation.
Ejemplos
70 kg adult, moderate activity, temperate
A typical office worker who exercises 3-4 times a week.
Resultado: ~2.3 L/day, ~9 cups of 8 oz
80 kg adult, very active, hot climate
A construction worker in summer.
Resultado: ~3.9 L/day, ~16 cups of 8 oz
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Last reviewed: 2026-09-25