Daily Water Intake Calculator
Calculate your daily water intake needs based on your weight, age, and activity level. Staying properly hydrated is essential for energy, focus, digestion, and overall health. Get your personalized hydration recommendation in ounces, liters, and glasses of water.
How to Use This Tool
1. Enter Weight
lbs or kg
2. Enter Age
Years
3. Select Activity
Sedentary to Very Active
4. Get Results
View recommended intake
Formula & Calculation
Sedentary: +0 oz | Lightly Active: +12 oz | Moderately Active: +24 oz | Very Active: +36 oz
Results are rounded to the nearest ounce for clarity.
Quick Reference Water Intake Table
| Weight (lbs) | Age 18–30 | Age 31–55 | Age 55+ |
|---|---|---|---|
| 120 | 80 | 80 | 72 |
| 140 | 93 | 93 | 84 |
| 160 | 107 | 107 | 96 |
| 180 | 120 | 120 | 108 |
| 200 | 133 | 133 | 120 |
How We Calculated
- Input: We collected your weight, age, and activity level.
- Base Calculation: Multiplied your weight (in lbs) by 2/3 to get the base intake.
- Activity Adjustment: Added extra ounces based on your activity level.
- Age Adjustment: Applied a slight reduction for older adults (55+).
- Result: Displayed your intake in ounces, liters, and glasses.
Why Trust This Tool?
Based on hydration research
No server storage
Use instantly
Works on all devices
Latest health research
No hidden charges
Accuracy & Standards
This calculator follows National Institutes of Health (NIH) hydration guidelines, using the formula of half your body weight in ounces plus activity adjustments. Results are rounded to the nearest ounce. The tool is for educational purposes—not a substitute for professional medical advice.
Unit Relationship
= 0.0296 L
= 33.814 oz
= 8 oz
Learn About Hydration
Why Hydration Matters
Water is essential for every cell, tissue, and organ in your body. It regulates temperature, transports nutrients, flushes waste, supports digestion, and lubricates joints. Staying hydrated is key to optimal health and performance.
Signs of Dehydration
Common signs include dark urine, dry mouth, fatigue, headache, dizziness, and decreased urine output. Thirst is a late indicator—by the time you feel thirsty, you're already mildly dehydrated.
Hydration Tips
Carry a water bottle, set reminders to drink, flavor water with fruit, eat water-rich foods (cucumbers, watermelon), and monitor urine color. Adjust intake based on activity and climate.
Real-World Examples
- Example 1: 150 lbs, age 30, Lightly Active → 112 oz (3.3 L, 14 glasses)
- Example 2: 180 lbs, age 45, Moderately Active → 144 oz (4.3 L, 18 glasses)
- Example 3: 140 lbs, age 60, Sedentary → 84 oz (2.5 L, 11 glasses)
Limitations of This Tool
- Provides estimates—individual hydration needs vary.
- Does not account for climate, pregnancy, breastfeeding, or medical conditions.
- Not suitable for children or athletes with extreme training loads.
- Always consult a healthcare professional for personalized advice.
Trust & Privacy
We take your privacy seriously. This tool:
- Does not store data on any server
- All calculations happen locally in your browser
- No cookies are used for this tool
References
- National Institutes of Health. Hydration Guidelines. NIH.gov.
- World Health Organization. Water and Health. WHO.int.
- Mayo Clinic. Water: How much should you drink every day? MayoClinic.org.
Editorial Process
The Healthtus editorial team reviews this tool regularly to ensure accuracy and alignment with the latest hydration research. We update the content and references as new research emerges.
Last reviewed: July 2026