Estimate how much water to drink each day from your body weight, activity level and climate, shown in ounces, millilitres, litres and cups. A built-in tracker lets you log what you drink through the day.
Calculate Daily Water Intake
ℹ️ Quick Calculation
Enter your basic information to get a recommended daily water intake based on your body weight and activity level.
Advanced Water Intake Calculator
ℹ️ Detailed Calculation
Get a more precise calculation by including additional factors like exercise duration, temperature, and special conditions.
Daily Water Tracker
ℹ️ Track Your Intake
Set your daily water goal and track your intake throughout the day.
Hydration Guide & Tips
💧 Why Hydration Matters
Water is essential for nearly every bodily function. Proper hydration improves physical performance, cognitive function, energy levels, and overall health. Even mild dehydration can impair mood, concentration, and physical capabilities.
Signs of Proper Hydration
✅ Well Hydrated
- Pale yellow or clear urine
- Regular urination (every 2-4 hours)
- Moist lips and skin
- Good energy levels
- No excessive thirst
⚠️ Dehydrated
- Dark yellow or amber urine
- Infrequent urination
- Dry mouth and lips
- Fatigue and dizziness
- Headaches
Hydration Tips
🌅 Start Your Day Right
Drink 16-24 oz of water within 30 minutes of waking up to rehydrate after sleep and kickstart your metabolism.
⏰ Set Reminders
Use phone alarms or apps to remind you to drink water throughout the day, especially during busy periods.
🍽️ Drink Before Meals
Consume 8-16 oz of water 30 minutes before meals to aid digestion and help control appetite.
🏃 Exercise Hydration
Drink 16-20 oz two hours before exercise, 8 oz during every 15-20 minutes, and 16-24 oz for every pound lost after.
🍉 Eat Water-Rich Foods
Include cucumbers, watermelon, celery, tomatoes, and leafy greens in your diet – they’re 90%+ water.
🥤 Carry a Water Bottle
Keep a reusable water bottle with you at all times. Mark it with time goals to track your progress.
🔬 Factors That Increase Water Needs
- Exercise: Add 12 oz for every 30 minutes of moderate to intense exercise
- Hot Weather: Increase intake by 16-32 oz in hot or humid conditions
- High Altitude: Add 16-24 oz when at elevations above 8,200 feet
- Illness: Fever, vomiting, or diarrhea require additional hydration
- Pregnancy: Increase by 24-32 oz daily (about 10 cups total)
- Breastfeeding: Increase by 32-40 oz daily (about 13 cups total)
- Alcohol/Caffeine: These are diuretics – match each serving with equal water
⚠️ When to Consult a Doctor
- If you have kidney problems, heart disease, or liver disease
- If you’re taking medications that affect fluid balance (diuretics, etc.)
- If you experience symptoms of severe dehydration (confusion, rapid heartbeat, etc.)
- If you have conditions like diabetes insipidus
What this water intake calculator does
- Basic Calculator: estimates a daily amount from your weight, activity level and climate.
- Advanced Calculator: also considers age, gender, exercise time and intensity, temperature, altitude, and pregnancy, breastfeeding or illness.
- Water Tracker: set a daily goal and log glasses as you drink them. Your log is stored only in your own browser and starts again each new day.
- Hydration Guide: a reference tab with general hydration information.
How it is calculated
The basic estimate is a rule of thumb: about 0.67 ounces of water per pound of body weight, multiplied by 1.0 to 1.4 for activity level, then plus 16 ounces for hot weather or minus 8 ounces for cold. The advanced tab starts from 0.7 oz per lb for men and 0.6 oz per lb for women and adds amounts for exercise, heat, altitude and special conditions.
Worked example: someone weighing 150 lb (68 kg) with a moderate activity level in a normal climate gets about 121 oz, which is about 3.6 litres.
How this compares with official figures
The U.S. National Academies set Adequate Intakes of 3.7 litres of total water a day for men and 2.7 litres for women, counting water from all beverages and food, and say these are not specific requirements (National Academies news release). They also note that people who are very active or live in hot climates may need more, and that thirst is enough for most healthy people to stay hydrated.
Things to keep in mind
This calculator uses simple rules of thumb, so treat the result as a rough guide. Needs vary with diet, health conditions and medications. If you are pregnant or breastfeeding, ill, or have a condition such as kidney or heart disease, ask your health care provider how much to drink. This calculator is for general information only and is not medical advice. If you have questions about your result, talk with your health care provider.
Frequently asked questions
Does coffee or tea count?
Beverages and food both contribute to total water intake, which is how the National Academies figures above are defined.
Will my tracker log carry over to tomorrow?
No. The running total resets each new day. Your daily goal is kept.
Looking for more? See all our free health and fitness calculators.