Why Hydration Matters
Water makes up about 60% of your body weight and is involved in virtually every biological process: nutrient transport, temperature regulation, joint lubrication, digestion, and cognitive function. Even mild dehydration of 1–2% of body weight can impair concentration, increase perceived effort during exercise, and reduce physical performance.
How Much Water Do You Need?
The widely cited “8 glasses a day” rule is not evidence-based — individual needs vary significantly with body size, activity, and climate. A more personalised starting point is 33 ml per kg of body weight, then adjusting upward for exercise and heat exposure.
Signs of Dehydration
Dark yellow or amber urine is the most reliable everyday indicator of dehydration. Other signs include fatigue, headache, dry mouth, decreased urine frequency, and difficulty concentrating. Thirst is a lagging indicator — by the time you feel thirsty, you may already be mildly dehydrated.
Frequently Asked Questions
Does coffee count towards daily water intake?
Yes. Despite its mild diuretic effect, research shows that coffee contributes positively to overall fluid balance. Tea, juice, and even food (especially fruits and vegetables) count towards your total.
Can you drink too much water?
Yes — though rare in healthy adults. Hyponatraemia (water intoxication) can occur when extremely large volumes are consumed in a short time, diluting blood sodium. This is most relevant for endurance athletes drinking large amounts of plain water.
Should I drink water before or after meals?
Both are fine. Drinking water before meals can reduce appetite and support weight management. There is no evidence that drinking during meals impairs digestion despite the popular belief.
Medical Disclaimer: This calculator is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for health decisions.