Popular ways for accessing body composition are body mass index(BMI) and body fat percentage. Body mass index factors in a persons height and weight to determine healthy weight range. Body fat percentage determines a persons body fat using various techniques with varying ranges of accuracy. The body mass index is an effective for the general population, but is not accurate for subsets of the population such as body builders and other athletes.
I prefer body fat as an indicator for a healthy body composition. You don't need to know your exact body fat number but narrowing it down to a range can be helpful in understanding your health. The easiest way to get an idea of your body fat percentage is to use a scale with a body fat function or use a handheld body fat tester. These methods won't be an exact measurement but they can provide you with a close enough body fat range to be constructive.