Knowing your body fat percentage is very important fro several reasons. The most important reason why everyone should measure their body fat percentage is so you can distinguish between fat and muscle and find out if you are healthy. The goal obviously is to get rid of fat and keep the muscle. The other reason is so you could get important feedback. Losing fat permanently is all about making small adjustments in the process.
The average body fat percentage is a little different between males and females because the hormone estrogen causes women to carry about 5% more body fat than men. Men have about 17% of body fat and females 23%. Your body fat also increases and lean body mass decreases when you get older. The average American loses 6.6 pounds of lean body mass every decade after age 20. For example if you weight has stayed the same since the age of 20 until 45 then you still gained fat.
Having an average body fat level would not be ideal at all. Nobody wants to be average. The optimal fat percentage for people who are not athletes is around 10-14% for men and 16-20% for women. Reaching those levels is possible for pretty much everyone.
If you want to be ripped and look like a fitness model then you need to drop your body fat percentage even lower. It all depends of your goals and how much effort you are willing to put in. Here are a few example of athletes and their body fat:
Typical average body fat for athletes male female
Distance runners 5-10% 10-16%
Elite marathon runners 3-5% 9-12%
Sprinters 5-12% 12-18%
Jumpers & hurdlers 6-13% 12-20%
Olympic gymnasts 5-8% 11-14%
Bodybuilders, contest condition 3-5% 8-12%
Bodybuilders, off season 6-12% 13-18%
Soccer players 7-12% 10-18%
Baseball/softball players 10-14% 12-18%
Pro basketball players 7-12% 10-16%
So having too much body fat is obviously bad for your health. Health problems including diabetes, high blood pressure, cardiovascular disease, cancer and osteoarthritis. Men are considered borderline at 25% body fat and clinically obese at 30%, while women are borderline at 30% and clinically obese at 35%