How to use this calculator
- 1
Enter your weight
Larger bodies need more fluid to support metabolism and temperature regulation.
- 2
Add exercise time
Include workouts, sports and active commutes. Sweat losses rise with intensity.
- 3
Choose your climate
Heat and humidity increase sweat losses, even at rest.
- 4
Track your glasses
Tap the glass icons through the day to see your hydration progress.
Real-world example
Jordan weighs 70 kg, runs for 60 minutes and lives in a hot climate. The recommendation is about 3.5 L, or 14 glasses of 250 ml, spread across the day, with extra fluids around the run.
Features, accuracy & limitations
Formula: 33 ml per kg of body weight + 350 ml per 30 minutes of exercise + 0.5–1.0 L for hot or very hot climates. One glass = 250 ml.
Key features
- Accounts for weight, exercise and climate
- Liters and glasses output
- Interactive daily hydration tracker
- Works in kg or lbs
Limitations
- Includes fluid from all beverages; food supplies ~20% of intake
- Individual sweat rates vary widely
- Not suitable for people on fluid restriction (heart, kidney, liver conditions)
- Very long endurance events also require electrolytes
Medical disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a medical diagnosis and does not replace advice from a doctor, registered dietitian, or other qualified health professional. Consult a professional before making changes to your diet, exercise, or health routine — especially if you are pregnant, under 18, or have a medical condition.