For a 70 kg adult, approximately how many liters of total body water are present?

For a 70 kg adult, approximately how many liters of total body water are present?

• A. 40 L
• B. 60 L
• C. 42 L
• D. 50 L

Answer: (C)

Total body water in a healthy adult is about 60% of body weight. For a 70 kg person, that’s 0.60 × 70 ≈ 42 liters, and since 1 liter of water has a mass of about 1 kg, TBW is roughly 42 L. This reflects the distribution into intracellular and extracellular compartments, with most TBW inside cells. The other numbers fall farther from the standard 60% estimate (for example, 40 L is a bit low, while 50 L or 60 L imply higher percentages than typical).

Total body water in a healthy adult is about 60% of body weight. For a 70 kg person, that’s 0.60 × 70 ≈ 42 liters, and since 1 liter of water has a mass of about 1 kg, TBW is roughly 42 L. This reflects the distribution into intracellular and extracellular compartments, with most TBW inside cells. The other numbers fall farther from the standard 60% estimate (for example, 40 L is a bit low, while 50 L or 60 L imply higher percentages than typical).