How much water should I drink per day?

A general guideline is about 35 ml per kilogram of body weight. For a 70 kg person, that's approximately 2,450 ml (about 2.5 liters or 10 cups). However, needs increase with physical activity, hot climates, pregnancy, breastfeeding, and certain health conditions. The 8x8 rule (eight 8-ounce glasses) is a simpler approximation at about 1.9 liters per day.

Does activity level affect water needs?

Yes, significantly. Exercise causes water loss through sweat. Moderately active people need about 500 ml more than sedentary individuals. Active people need about 1,000 ml extra, and athletes engaged in intense training may need 1,500 ml or more additional water per day. Drink water before, during, and after exercise.

Does coffee count toward water intake?

Yes, moderate coffee and tea consumption does count toward your daily fluid intake. While caffeine has a mild diuretic effect, the water content more than compensates. However, plain water remains the best choice for hydration. Very high caffeine intake (more than 400mg/day) may have a more pronounced diuretic effect.

How do I know if I'm drinking enough water?

The easiest indicator is urine color: pale yellow to clear indicates good hydration, while dark yellow suggests you need more water. Other signs of dehydration include thirst, dry mouth, fatigue, headache, and decreased urine output. Drink water consistently throughout the day rather than large amounts at once.

Water Intake Calculator

Weight Unit

Weight

Activity Level

Climate

Daily Water Intake

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In Liters

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In Cups (250 ml)

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In Fluid Ounces

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How the Water Intake Calculator Works

This water intake calculator estimates your daily hydration needs based on your body weight, physical activity level, and the climate you live in. Proper hydration is essential for regulating body temperature, transporting nutrients, supporting digestion, maintaining joint health, and nearly every other bodily function.

The calculation starts with a base of 35 ml per kilogram of body weight, which is the commonly recommended amount for healthy adults. Activity-level adjustments add extra water to compensate for sweat losses: +500 ml for moderate exercise, +1,000 ml for active lifestyles, and +1,500 ml for athletes. Living in a hot or humid climate adds another 500 ml to account for increased perspiration.

Results are displayed in milliliters, liters, cups (250 ml each), and fluid ounces to accommodate different measurement preferences. Keep in mind that about 20% of daily water intake typically comes from food, especially fruits and vegetables with high water content like watermelon, cucumbers, and oranges. Beverages like tea, coffee, and milk also contribute to hydration. The best indicator of adequate hydration is pale yellow urine throughout the day. Individual needs may vary based on age, health conditions, medications, pregnancy, and breastfeeding status.

Daily Water Intake Recommendations by Weight

Body Weight	Sedentary	Moderate Activity	Active / Hot Climate
120 lb (54 kg)	1.9 L / 64 oz	2.4 L / 81 oz	2.9 L / 98 oz
140 lb (64 kg)	2.2 L / 75 oz	2.7 L / 92 oz	3.2 L / 109 oz
160 lb (73 kg)	2.5 L / 86 oz	3.1 L / 103 oz	3.6 L / 120 oz
180 lb (82 kg)	2.9 L / 97 oz	3.4 L / 114 oz	3.9 L / 131 oz
200 lb (91 kg)	3.2 L / 107 oz	3.7 L / 124 oz	4.2 L / 141 oz
220 lb (100 kg)	3.5 L / 118 oz	4.0 L / 135 oz	4.5 L / 152 oz
250 lb (113 kg)	4.0 L / 134 oz	4.5 L / 151 oz	5.0 L / 168 oz

Based on ~35 ml per kg body weight baseline. About 20% of daily intake typically comes from food.

Disclaimer: This calculator provides estimates for informational purposes only. Consult a healthcare professional before making health or dietary decisions.

Water Intake Calculator

How the Water Intake Calculator Works

Daily Water Intake Recommendations by Weight

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