Free Water Intake Calculator
Enter your weight and daily exercise minutes to instantly find out how many liters and glasses of water you need per day. Science-backed, private, and free.
Hydration Workbench
Define your physiological parameters to synthesize your daily water quota.
FORMULA: Hydration = (Weight × 0.033) + (Activity / 30 × 0.5)How It Works
This calculator uses the widely accepted formula of 33ml of water per kilogram of body weight as the baseline daily requirement. It then adds 500ml for every 30 minutes of exercise you do, accounting for fluid lost through sweat. The result is your personalized daily water target — shown in litres, millilitres, and glass count.
You don't need to count every sip. Just check your target once and use the glass count to track through the day.
Why Hydration Matters More Than You Think
A Simple Daily Hydration Schedule
Spreading intake throughout the day is more effective than drinking large amounts at once.
Accuracy & Limitations
The 33ml/kg formula is a reliable baseline for healthy adults in temperate climates. Your actual needs may be higher in hot weather, at altitude, during illness, or if you eat a high-sodium diet. People with kidney or heart conditions should follow guidance from their doctor rather than general formulas. For a complete health picture, explore our BMR Calculator, BMI Calculator, and the Ideal Weight Calculator.
Common Questions
The standard formula is 33ml per kg of body weight. For a 70 kg adult that's about 2.3 litres (roughly 9 glasses) before adding exercise. Our calculator applies this instantly and adjusts for your workout duration.
Using a standard 250ml glass, 2 litres equals 8 glasses. Our calculator shows your target in both litres and glass count so you can track it without measuring.
Yes. Drinking water before meals reduces appetite and increases metabolism by up to 30% for 30–60 minutes. Replacing sugary drinks with water also reduces daily calorie intake significantly.
Add approximately 500ml per 30 minutes of moderate to vigorous exercise. Our calculator does this automatically when you enter your exercise duration.
Early signs of dehydration include dark yellow urine, dry mouth, fatigue, mild headaches, and difficulty concentrating. If your urine is pale yellow, your hydration is on track.
Yes. All non-alcoholic fluids including tea, coffee, and juice count toward your daily total. However, caffeinated drinks have a mild diuretic effect, so pure water remains the most efficient source.
No. All calculations happen inside your browser in real time. We do not collect, store, or transmit any personal data you enter.