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Free Tool
Find out exactly how much water your body needs each day based on your weight, activity level, and climate. No guesswork, no sign-up — just a clear daily target.
Your baseline daily water need is calculated by multiplying your body weight in kilograms by 0.033. For a 75 kg person, that gives a base of roughly 2.5 litres per day. This accounts for normal body functions — digestion, temperature regulation, joint lubrication, and nutrient transport.
When you exercise, your body loses water through sweat. The harder and longer the session, the more fluid you need to replace. Sedentary individuals need no extra on top of the base, while athletes training intensely may need an additional litre or more to stay properly hydrated and maintain performance.
Hot and humid environments increase sweat production, so you need more water to compensate. Cold climates can also increase fluid needs — cold air holds less moisture, and you lose water through respiration and may not feel as thirsty, leading to under-hydration if you are not proactive.
Mild dehydration can affect your energy, focus, and physical performance before you even feel thirsty. Watch for these common signs:
Individual variation: This calculator provides a practical starting point, but your actual needs can vary based on age, body composition, diet (water-rich foods contribute to hydration), caffeine and alcohol intake, altitude, and any medical conditions. Pregnant or breastfeeding individuals typically need additional fluid. If in doubt, consult a healthcare professional. The simplest day-to-day check is urine colour — pale straw means you are well hydrated.
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