Daily Water Intake Calculator - How Many Liters Per Day
Calculate daily water intake needs based on body weight, activity level, climate conditions, and health status. Health calculator for hydration planning, fitness, and medical recommendations. Based on National Academies of Sciences guidelines.
Water Intake Formula
Water (ml) = Body Weight (kg) × 30-40 mlVariables:
- SedentaryMinimum requirementMinimum requirement(e.g.: 30 ml/kg BW)
- ActiveWith exerciseWith exercise(e.g.: 35-40 ml/kg BW)
- Hot WeatherAdditional sweat lossAdditional sweat loss(e.g.: +500-1000 ml)
How to Use
- 1
Enter Body Weight
Input weight in kilograms.
- 2
Select Activity Level
Sedentary, active, or very active.
- 3
Environmental Conditions
Hot/humid weather, air conditioning, etc.
- 4
View Results
Daily water needs in liters/glasses.
Examples
Active Adult
Problem:
Weight 70 kg, exercise 3x/week. Daily water needs?
Solution:
- 1.Moderate activity factor: 35 ml/kg
- 2.Water = 70 × 35 = 2450 ml
- 3.≈ 2.5 liters = 10 glasses
Result:2.5 liters/day (10 glasses)
Add 500 ml for each hour of exercise.
Hot Weather
Problem:
Weight 60 kg, hot weather 35°C.
Solution:
- 1.Base: 60 × 30 = 1800 ml
- 2.Hot weather addition: +500 ml
- 3.Total: 2300 ml
Result:2.3 liters/day
In hot weather, the body loses more water through sweat.
Frequently Asked Questions
How many glasses of water per day?
The general "8 glasses per day" guideline (≈2 liters) is a rough estimate. Actual needs vary from 2–3+ liters depending on weight, activity, weather, and diet.
Do tea and coffee count?
Partially yes. Caffeine is mildly diuretic but tea and coffee still contribute fluids. Plain water remains best. Fruits and vegetables also contain water.
What are signs of dehydration?
Dark urine, excessive thirst, dry mouth, dizziness, headache, fatigue. Ideal urine is light yellow and clear.
Can you drink too much water?
Rarely, but yes (hyponatremia). It occurs when drinking very large amounts (>5–6 liters) quickly without electrolytes. Endurance athletes should be cautious.