CalcDaily Water Intake Calculator
Last updated: 2026-05-09
The Daily Water Intake Calculator is a free health calculator. Calculate how many litr is of water you should drink per day based on weight and exercise. Get evidence-based estimates to improve your wellbeing.
Inputs
Result
Enter values and press Calculate
Was this helpful?
📄 Save your calculation as PDF
Enter your email and download a PDF report with your results.
Common Sizes — Click to Fill
| Daily exercise (min) (min/día) | Weight (kg) (kg) | |
|---|---|---|
| Child | 15 min/día | 35 kg |
| Teen | 20 min/día | 52.5 kg |
| Adult (F) | 30 min/día | 70 kg |
| Adult (M) | 45 min/día | 105 kg |
| Elderly | 60 min/día | 140 kg |
How much water do you need per day?
Your daily water intake needs depend on your weight, physical activity level, climate, and health status. The most widely accepted scientific formula is 35 ml per kilogram of body weight, adjusted for activity level. This can range from about 2 liters to 3.5+ liters per day for active individuals.
Daily hydration formula
Base water = Weight (kg) × 35 ml
Add 500–750 ml per hour of moderate exercise (more in hot climates).
Practical example
Person of 70 kg with moderate activity (30 min exercise/day):
- Base water: 70 × 35 = 2,450 ml
- Exercise adjustment: +500 ml
- Total: 2,950 ml ≈ 3 liters per day
Signs of dehydration
- Dark urine: Urine should be pale yellow.
- Dry mouth and thirst: Thirst already indicates mild dehydration.
- Fatigue and headaches: Often caused by insufficient hydration.