The most recommended way of assessing your ideal weight is to calculate your Body Mass Index, or BMI. This calculation utilizes your height and weight, but not your age , There are many ways to calculate ideal body weight which depends also in age but it is more complicated. The Centers for Disease Control and Prevention warn that an ideal weight calculated by BMI should not be taken by itself. Other factors, such as genetics, gender, and muscle weight, should all be taken into account to find your ideal weight. It is best to consult a physician to discuss all of these factors and to determine the best weight for you. 1- Determine your weight in pounds. Use a scale that has been calibrated to give the most correct weight as possible. Wear as little clothing as possible to determine the most accurate weight of your body. 2-Measure your height in inches. Use a measuring tape starting from the bottom of your foot and going to the top of your head. For best results, take off your shoes and hat. 3- Disregard your age. Age will be used for children and teens from age 2 to 19 years old. Age is not the best determinant of ideal weight for adults, although it can become a factor again when you become older. 4- Calculate your BMI using your height and weight. The equation is: Weight (lb) / [height (in)]Â² x 703. The CDC gives an example with a weight of 150 lbs and a height of 65 inches. In this case, the calculation would be [150 / (65)Â²] x 703 = 24.96. Your physician or fitness expert can assist you with this calculation if needed. 5- Compare your BMI result to recommended BMI numbers. The American Council on Exercise gives the following recommendations: a BMI of less than 18.5 is underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight, and over 30 is obese. Consult your physician, and possibly a fitness and nutrition expert as well, on increasing or lowering your BMI to a normal level. Source