Find your personalized daily water intake recommendation based on your body weight, activity level, and climate. See your target in cups, ounces, and liters. Free, no signup.
Calculate Daily Water Intake
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liters per day
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LITERS
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FL OZ
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CUPS (8oz)
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Your daily water goal visualized (each 💧 = 1 cup / 8 oz):
How your total is calculated:
Base (weight-based)—
Activity adjustment—
Climate adjustment—
Total daily target—
How Much Water Do You Actually Need?
The popular "8 glasses a day" (64 oz / 1.9L) rule is a rough starting point, but it doesn't account for individual differences. The National Academies of Sciences recommends 3.7 liters/day for men and 2.7 liters/day for women from all sources — including food (which provides about 20% of daily fluid intake).
Our calculator uses a weight-based formula: approximately 30–35ml per kg of body weight as a base, then adjusts for activity and climate. This aligns with NHS and WHO recommendations for individualized hydration targets.
Signs of dehydration
Dark yellow urine (pale yellow = well hydrated)
Fatigue and reduced concentration — even mild dehydration (1–2%) impairs cognitive performance
Headache, dry mouth, dizziness
Reduced physical performance
Increased heart rate during exercise
💡 The urine color test
The easiest way to monitor hydration: check urine color. Pale straw yellow = well hydrated. Dark yellow or amber = drink more. Clear/colorless = possibly overhydrated (rare but possible). Vitamin B supplements can temporarily turn urine bright yellow regardless of hydration status.
How to Hit Your Daily Water Target
Start the day with water. Drink a large glass immediately upon waking — you've gone 7–8 hours without fluids.
Drink before meals. A glass 20–30 minutes before each meal adds ~3 cups without effort and may reduce calorie intake.
Carry a reusable water bottle. People who carry water bottles drink significantly more throughout the day.
Set hourly reminders during work hours to take a few sips.
Eat water-rich foods. Cucumber (96% water), watermelon (92%), strawberries (91%), and lettuce (95%) all contribute to daily fluid intake.
Drink more in heat and during exercise. Add 12 oz (350ml) per 30 minutes of vigorous exercise.
Frequently Asked Questions
Can you drink too much water?
Yes, though it's rare in everyday life. Hyponatremia (water intoxication) occurs when excessive water intake dilutes sodium in the blood to dangerous levels. It's most common in endurance athletes who drink large amounts of plain water without replacing electrolytes. For most people, kidneys can process up to 800–1000ml per hour, so casual overdrinking is not a concern.
Does coffee and tea count toward my water intake?
Yes. Despite the mild diuretic effect of caffeine, research consistently shows that caffeinated beverages still provide a net positive contribution to hydration. Up to 400mg of caffeine daily (about 4 cups of coffee) does not cause net fluid loss in habituated coffee drinkers. Plain water remains optimal, but coffee and tea do count.
Should I drink more water while pregnant?
Yes. During pregnancy, the recommended intake increases to about 2.4 liters (10 cups) per day. During breastfeeding, the recommendation increases further to approximately 3.1 liters (13 cups) per day, as milk production requires significant additional fluid. Consult your healthcare provider for personalized guidance.