What percentage of a person's body mass is approximately water?

The average percentage of water in a person's body mass is approximately 60%. This figure can vary depending on several factors, including age, gender, and body composition. For instance, infants can have a higher water percentage, around 75-78%, while adults tend to average around 60%. Men typically have a higher percentage of body water compared to women due to higher muscle mass, as muscle tissue contains more water than fat tissue.

The figure of 70% is sometimes referenced in general discussions about body water but does not accurately reflect the average across all individuals. Similarly, the percentages of 80% and 90% are considerably higher than what is typical in human adults. Understanding body composition can help inform hydration needs and overall health.