To find the proper weight for a person's specific age, take height into account, according to Medical News Today. Many people choose to use Body Mass Index (BMI) as a means of measuring how much they should weigh.
To measure BMI, take the weight in pounds, multiply it by 703 and divide it by the square of the height in inches. A BMI below 18.5 is underweight, between 18.5 and 25 is ideal, 25 to 30 is overweight and over 30 is obese.
While many clinicians use BMI, some feel it is too rudimentary to rely on. Other factors can contribute to how much a person should weigh, such as their muscle mass and bone density.