Body Water Calculator
70 kg
170 cm
30 years
Hydration Analysis
Total Body Water (TBW):
42.3 L
Percentage of Body Weight:
60.4%
Hydration Status:
Normal Hydration
Note: Results based on Watson formula. Athletes may have 5-10% higher values. Consult a doctor for clinical hydration assessment.
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Estimate your total body waterAbout Total Body Water
Total Body Water (TBW) represents the total amount of fluid in the human body, crucial for maintaining vital functions. Adult bodies are 50-65% water, varying by age, gender, and body composition.
Watson Formula for TBW
Calculation Method
Most accurate clinical formula for adults:
- Men: 2.447 - (0.09156 × age) + (0.1074 × height) + (0.3362 × weight)
- Women: -2.097 + (0.1069 × height) + (0.2466 × weight)
Where:
Age = years
Height = cm
Weight = kg
Normal Ranges
| Population | % Body Water |
|---|---|
| Adult Men | 60-65% |
| Adult Women | 50-55% |
| Infants | 75-78% |
| Elderly | 45-50% |
| Athletes | 65-70% |
Factors Affecting Body Water
- Body Composition: Muscle contains 75% water vs fat's 10%
- Age: Decreases 15-20% from infancy to old age
- Gender: Men typically have 5-10% more water
- Pregnancy: Increases TBW by 6-8 liters
- Climate: Heat increases water needs by 1-3L/day
- Altitude: Higher elevation increases respiratory water loss
- Diet: High sodium increases water retention
- Health Conditions: Diabetes, kidney disease affect balance
Hydration Impact on Health
| Water Loss | Symptoms | Health Risks |
|---|---|---|
| 1-2% Body Weight | Thirst, fatigue | Reduced cognitive function |
| 3-5% Body Weight | Dry mouth, headache | Heat exhaustion |
| 6-8% Body Weight | Dizziness, confusion | Heat stroke |
| >10% Body Weight | Muscle spasms | Organ failure |
Daily Water Sources
- Fluids: 70-80% (water, beverages)
- Food: 20-30% (fruits, vegetables)
- Metabolic Water: 10% (cellular respiration)
Overhydration Risks
- Hyponatremia (low sodium)
- Nausea/Headaches
- Brain swelling (severe cases)
- Limit: 1L/hour maximum
Clinical Considerations
- ICU patients require precise fluid monitoring
- Diuretics can alter TBW by 2-5%
- Burn victims may lose 10-15% TBW daily
- Dialysis patients require strict fluid control