How much water should I drink?

A general rule is 30-35 ml per kg of body weight. Active people need more. The '8 glasses a day' (2 liters) is a rough guide. Adjust based on activity level and climate.

Does coffee count as water intake?

Caffeine is a mild diuretic, but coffee/tea still count toward hydration. However, water is still the best choice. Limit caffeinated beverages and prioritize plain water.

How does activity level affect water needs?

Active people need more water. Sedentary: base amount. Light exercise: +20%. Moderate: +40%. Intense: +60%. Athletes: +80%. Adjust based on sweat loss.

What are signs of dehydration?

Signs include dark urine, fatigue, headache, dizziness, dry mouth, and decreased urine output. Drink water immediately if you experience these symptoms.

Can I drink too much water?

Yes, but it's rare. Drinking excessive amounts (over 1 liter per hour) can cause hyponatremia (low sodium). Stick to recommended daily amounts and spread intake throughout the day.

When should I drink more water?

Drink more in hot weather, high altitude, during illness, when pregnant/breastfeeding, and before/during/after exercise. Listen to your body's thirst signals.

Water Intake Calculator

Calculate your daily water intake needs. Enter your weight and activity level to automatically calculate recommended water intake in liters, glasses, and fluid ounces.

Calculator

Result

0.0

Liters

0

Glasses (250ml)

0

Fluid Ounces

Formula & Guide

Formula

B

Base Intake

Base = Weight (kg) × 33 ml

30-35 ml per kg of body weight

A

Adjusted Intake

Adjusted = Base × Activity Factor

Multiply by activity level (1.0-1.8)

Formula Variables

W

Weight

Body weight in kilograms (kg)

B

Base Intake

Base water intake in milliliters (Weight × 33 ml)

AF

Activity Factor

Activity level multiplier (1.0-1.8)

A

Adjusted Intake

Final water intake adjusted for activity (Base × AF)

Step-by-Step Scenario

Example Scenario

Weight

70 kg

Activity

Moderate (1.4)

1

Calculate Base Intake

Base = 70 × 33 = 2,310 ml = 2.31 liters

Multiply weight by 33 ml to get base intake

2

Apply Activity Factor

Adjusted = 2,310 × 1.4 = 3,234 ml

Result: 3.2 liters (13 glasses)

Additional Examples

Sedentary

Weight: 60 kg

Activity: Sedentary (1.0)

Water

2.0 liters (8 glasses)

Athlete

Weight: 80 kg

Activity: Athlete (1.8)

Water

4.8 liters (19 glasses)

Characteristics of Water Intake

Weight-Based Formula

Base calculation uses 30-35 ml per kg of body weight. Simple and personalized to your weight.

Activity Adjustment

Activity level adjusts intake: Sedentary (1.0), Light (1.2), Moderate (1.4), Intense (1.6), Athlete (1.8).

Multiple Units

Shows intake in liters, glasses (250ml), and fluid ounces. Easy to understand and track daily.

Health Essential

Proper hydration is essential for health. Prevents dehydration, supports metabolism, and improves physical performance.

Important Notes

Base water intake: 30-35 ml per kg of body weight. For example, 70 kg person needs 2,100-2,450 ml (2.1-2.5 liters) base.
Activity factors: Sedentary 1.0, Light exercise 1.2, Moderate 1.4, Intense 1.6, Athlete 1.8. Active people need significantly more water.
Drink more in hot weather, high altitude, during illness, when pregnant/breastfeeding, and before/during/after exercise.
Signs of dehydration: dark urine, fatigue, headache, dizziness, dry mouth. Drink water immediately if you experience these.
Spread water intake throughout the day. Don't drink all at once. Aim for consistent hydration rather than large amounts at once.

Frequently Asked Questions

Find answers to common questions about daily water intake.