How Much Should I Weigh?

Most people have at some point tried to lose weight or at least known someone who has. This is largely due to the perception of an “ideal” body weight, often based on what we see promoted through various media like social media, TV, movies, magazines, etc. Although ideal body weight (IBW) today is sometimes based on visual appeal, IBW was originally introduced to estimate medical dosages, and the formulas used to calculate it are not related to how a person looks at a given weight. It has since been found that the metabolism of certain drugs depends more on IBW than total body weight. Today, IBW is also widely used in sports, as many sports categorize athletes based on body weight.

However, IBW is not a perfect measurement. It does not account for body fat and muscle percentages. This means highly fit athletes may be considered overweight based on their IBW. Therefore, IBW should be viewed as an imperfect measure—not necessarily an indicator of health or a weight to strive for. It is possible to be over or under your “IBW” and still be perfectly healthy.

Determining how much a person should weigh is not an exact science. It varies greatly from person to person. No measure—whether IBW, body mass index (BMI), or any other—can definitively state the exact weight a person should be for optimal health. These are only general references. Focusing on healthy habits like regular exercise, eating unprocessed foods, and getting enough sleep is more important than chasing a specific weight based on a formula.

That said, many factors influence ideal weight. The major ones are listed below, though others—such as health conditions, fat distribution, and genetics—also play a role.

Age

In theory, age should not significantly affect IBW past 14-15 for girls and 16-17 for boys, as most people stop growing by then. In fact, men and women lose about 1.5 and 2 inches in height, respectively, by age 70. As people age, muscle mass decreases, and excess fat accumulates more easily. While this is natural, the effects of aging can be reduced through diet, exercise, stress management, and proper sleep.

Gender

Generally, women weigh less than men, even though they naturally have a higher body fat percentage. This is because men typically have more muscle mass, which is heavier than fat. Women also tend to have lower bone density. Additionally, men are usually taller than women.

Height

Taller individuals have more muscle mass and body fat, leading to higher weight. A man of the same height as a woman should weigh about 10-20% more.

Body Frame Size

Body frame size significantly impacts ideal weight measurements. It is categorized as small, medium, or large boned, based on wrist circumference relative to height:

For women:

• Height under 5’2″
  • Small boned = wrist under 5.5″
  • Medium boned = wrist 5.5″ to 5.75″
  • Large boned = wrist over 5.75″
• Height between 5’2″ and 5’5″
  • Small boned = wrist under 6″
  • Medium boned = wrist 6″ to 6.25″
  • Large boned = wrist over 6.25″
• Height over 5’5″
  • Small boned = wrist under 6.25″
  • Medium boned = wrist 6.25″ to 6.5″
  • Large boned = wrist over 6.5″

For men (height over 5’5″):

• Small boned = wrist 5.5″ to 6.5″
• Medium boned = wrist 6.5″ to 7.5″
• Large boned = wrist over 7.5″

A large-boned person will weigh more than a small-boned person at the same height, affecting IBW and BMI calculations.

Formulas for Finding Ideal Weight

IBW formulas were primarily developed for medical dosage calculations. All formulas follow the same structure: a base weight for 5 feet, with an added weight per inch over that height. For example, a 5’10” male using the Devine formula would add (2.3 × 10) kg to 50 kg, resulting in 73 kg (~161 lbs).

Different formulas use varying values based on research findings. The Devine formula is the most widely used.

G. J. Hamwi Formula (1964)

• Male: 48.0 kg + 2.7 kg per inch over 5 feet
• Female: 45.5 kg + 2.2 kg per inch over 5 feet
  (Developed for medicinal dosage purposes.)

B. J. Devine Formula (1974)

• Male: 50.0 kg + 2.3 kg per inch over 5 feet
• Female: 45.5 kg + 2.3 kg per inch over 5 feet
  (Originally for medical dosages, later adopted as a universal IBW standard.)

J. D. Robinson Formula (1983)

• Male: 52 kg + 1.9 kg per inch over 5 feet
• Female: 49 kg + 1.7 kg per inch over 5 feet
  (A modification of the Devine formula.)

D. R. Miller Formula (1983)

• Male: 56.2 kg + 1.41 kg per inch over 5 feet
• Female: 53.1 kg + 1.36 kg per inch over 5 feet
  (Another Devine formula adjustment.)

Healthy BMI Range

The World Health Organization (WHO) recommends a BMI of 18.5–25 for both men and women. BMI is a quick way to estimate a healthy weight for a given height.

BMI is widely used in medicine to assess health risks. Higher BMIs are linked to obesity, diabetes, heart disease, and other conditions. Doctors use BMI to identify potential health issues, especially if it increases over time. It is the official metric for classifying obesity levels.

Healthy BMI Range for Children

The formulas above apply to adults (18+). For children and teens, refer to the CDC’s BMI charts:

• CDC BMI chart for boys (ages 2–20)
• CDC BMI chart for girls (ages 2–20)
  The CDC recommends children maintain a BMI between the 5th and 85th percentile for their age.

Limitations of Our IBW Calculator

All formulas have limitations. They are designed for broad applicability, so they cannot be perfectly accurate for every individual. They only consider height and gender—not physical disabilities, extreme body types, activity levels, or body composition (muscle-to-fat ratio).

Our Ideal Weight Calculator provides general estimates based on common formulas. Its results are not strict targets but guidelines for reference.