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Health & Fitness

Daily Water Intake Calculator

Calculate your daily water needs by weight and activity level.

This tool is for informational purposes only. If you have kidney disease or other medical conditions, consult a doctor regarding your daily fluid needs.

Why the '8 Glasses' Rule Doesn't Apply to Everyone

You have probably heard the "everyone should drink 8 glasses of water" rule. The problem is that this rule ignores the difference between 60 kg and 100 kg, activity level, or hot weather. The daily water intake calculator lets you set a personal target based on your weight and lifestyle.

Effect of Exercise and Weather

Significant fluid loss occurs through sweating during exercise. General guideline: 400–600 ml two hours before exercise, 150–250 ml every 15–20 minutes during exercise, and approximately 500 ml per kilogram of weight lost afterwards.

Signs of Dehydration

Dark yellow urine, headache, fatigue and difficulty concentrating are early signs of dehydration. Even a fluid loss of 2% of body weight negatively affects physical and cognitive performance.

Frequently Asked Questions

Needs vary by weight and activity level; the formula is weight (kg) × 35 ml. For example, a sedentary 70 kg person needs about 2.45 litres per day, while a very active person may exceed 3.5 litres. The '8 glasses' rule is a good starting point for many but doesn't fit everyone.

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