Find Your Daily Water Target Based on How You Live
Enter your weight, age, activity level, and climate to get a personalized daily water intake recommendation. Add your current intake to see a live hydration score.
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Water Intake Calculator
Get your personalized daily water target based on weight, age, activity, and climate. Add your current intake to see a hydration score.
Gender
Unit System
Used to calculate your hydration score.
Personalized to Your Weight and Age
The baseline is 35 ml per kilogram of body weight, adjusted for age (children and teens need 10% more, adults over 65 need 10% less). Enter your weight in kg or lb -- the calculator converts automatically.
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Activity and Climate Adjustments
Activity multipliers range from 1.0x (sedentary) to 1.6x (very active). Climate adjustments apply 1.3x for hot weather, 1.2x for humid conditions, and 0.9x for cold. The final recommendation combines both factors.
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Hydration Score from Your Current Intake
Enter how much water you already drink per day to get a hydration score out of 100. The score reflects how close your current intake is to the recommendation -- from severely dehydrated to optimally hydrated.
Calculate NowGet your water target in three steps
Enter your details
Select gender, unit system (metric or imperial), and fill in your weight and age. Results update automatically as you type.
Set activity and climate
Choose your typical activity level and the climate you live in. For females, check pregnant or breastfeeding if applicable to add the relevant extra intake.
Add your current intake for a hydration score
Enter how many liters you currently drink per day. The hydration score chart updates to show where you stand relative to your target.
Deep Dive
How the Calculation Works
The calculator applies a weight-based formula with multipliers for each personal factor.
What Makes This Calculator Useful
Metric and Imperial
Enter weight in kg or lb -- auto-converted.
Activity and Climate
5 activity levels and 4 climate types for a precise result.
Hydration Score
Compare current intake to target and see your score out of 100.
Pregnancy Support
Adjusted intake for pregnant and breastfeeding women.
Who Uses It
Who Uses This Calculator
Anyone who wants to understand their daily hydration needs.
Frequently Asked Questions
How does the calculator determine my daily water target?
The base is 35 ml per kilogram of body weight. This is adjusted for age (10% more for under 18, 10% less for over 65), then multiplied by an activity factor (1.0x to 1.6x) and a climate factor (0.9x to 1.3x). For pregnant women, 300 ml is added; for breastfeeding, 700 ml is added. The result is rounded to the nearest 0.1 liter.
How much water should I drink per day?
The commonly cited "8 glasses" (about 2 liters) is a rough average. Actual needs vary significantly: a 90 kg active person in a hot climate may need over 4 liters, while a sedentary 55 kg adult in a temperate climate may need closer to 1.9 liters. This calculator uses your personal data to give a more relevant number.
Does my activity level significantly change the recommendation?
Yes. Activity multipliers range from 1.0x (sedentary) to 1.6x (very active). For a 70 kg person, this means the difference between roughly 2.5 liters and 4 liters per day. Selecting the right level makes the recommendation meaningful rather than generic.
How does climate affect my hydration needs?
Hot climates apply a 1.3x multiplier because heat increases sweat loss. Humid climates apply 1.2x because sweat evaporates less efficiently, causing more to be produced. Cold climates apply 0.9x because sweating is reduced, though indoor heating can increase respiratory fluid loss. Temperate is 1.0x baseline.
What is the hydration score and how is it calculated?
The hydration score (0-100) compares your current daily intake to the recommended amount. Scores above 80 indicate well to optimally hydrated. Scores 50-80 indicate mild to moderate dehydration. Below 50 suggests significant dehydration. The score also handles over-hydration, capping at 100 and penalizing intake above 120% of the recommendation.
What counts toward my daily water intake?
All fluids contribute, including plain water, tea, coffee, milk, juice, and soups. Water-rich foods like fruits and vegetables also provide some fluid. The calculator focuses on total fluid intake, but plain water is the most direct way to meet your daily target.
Ready to Know Your Water Target?
Enter your details and get a personalized daily water recommendation in seconds.