Water Intake Calculator
Hydration Tips
Signs of Dehydration
- • Dark yellow urine
- • Headaches
- • Fatigue or dizziness
- • Dry mouth and lips
- • Decreased urine frequency
Stay Hydrated
- • Start your day with water
- • Keep a water bottle nearby
- • Eat water-rich foods
- • Set reminders to drink
- • Drink before you feel thirsty
Quick Reference
General Rule
30-35 mL per kg body weight
Simple Formula
Half your body weight (lbs) in ounces
Related Calculators
Understanding Hydration
Why Water is Essential
Water makes up about 60% of your body weight and is involved in nearly every bodily function. It regulates temperature, transports nutrients, removes waste, lubricates joints, and supports cellular function.
Physical Performance
Even 2% dehydration can impair physical performance, reducing endurance, strength, and increasing fatigue.
Brain Function
Mild dehydration (1-3%) can impair mood, concentration, and increase headache frequency.
Metabolism
Proper hydration supports metabolic processes and may help with weight management.
How Much Water Do You Need?
The commonly cited "8 glasses a day" rule is a reasonable starting point but isn't based on strong science. Actual needs vary based on body size, activity, climate, and diet.
General Guidelines
| Group | Daily Intake |
|---|---|
| Adult Men | 3.7 L (125 oz) |
| Adult Women | 2.7 L (91 oz) |
| Pregnant Women | 3.0 L (101 oz) |
| Breastfeeding Women | 3.8 L (128 oz) |
Note: These amounts include water from all sources (beverages and food).
Signs of Dehydration
Mild Dehydration
- • Thirst
- • Dark yellow urine
- • Dry mouth
- • Slight headache
- • Decreased urination
Severe Dehydration
- • Very dark urine or no urination
- • Rapid heartbeat
- • Dizziness or confusion
- • Sunken eyes
- • Extreme fatigue
The Urine Color Test
Your urine color is one of the best indicators of hydration status:
Water Sources
About 20% of your daily water intake typically comes from food, especially water-rich fruits and vegetables:
Special Considerations
Exercise Hydration
- • Before: 500-600 mL 2-3 hours before exercise
- • During: 200-300 mL every 15-20 minutes
- • After: 1.5L for every kg lost during exercise
- • For exercise >1 hour, consider electrolyte drinks
Can You Drink Too Much Water?
Yes, though rare. Overhydration (hyponatremia) dilutes blood sodium levels and can be dangerous. It's most common in endurance athletes who drink excessive water without electrolytes. Symptoms include nausea, headache, confusion, and in severe cases, seizures. Let thirst be your guide and don't force excessive water intake.
Frequently Asked Questions
How much water should I drink per day?
General guidelines suggest about 3.7 liters (125 oz) for men and 2.7 liters (91 oz) for women from all sources (beverages and food). A simple formula is to drink half your body weight (in pounds) in ounces of water. Needs increase with exercise, heat, and certain health conditions.
Is the '8 glasses a day' rule accurate?
The 8x8 rule (eight 8-ounce glasses) is a reasonable starting point but isn't scientifically precise. Actual needs vary based on body size, activity level, climate, and diet. Some people need more, others less. A better guide is urine color - pale yellow indicates good hydration.
What are the signs of dehydration?
Early signs include thirst, dark yellow urine, dry mouth, fatigue, and headache. Severe dehydration symptoms include rapid heartbeat, dizziness, confusion, very dark urine or no urination, and sunken eyes. If you experience severe symptoms, seek medical attention immediately.
Can I drink too much water?
Yes, though rare. Overhydration (hyponatremia) dilutes blood sodium to dangerous levels. It most commonly occurs in endurance athletes who drink excessive water without electrolytes. Symptoms include nausea, headache, confusion, and in severe cases, seizures. Let thirst guide you rather than forcing excess water.