Ideal Body Weight Calculator

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Ideal Weight Calculator

About this calculator

The Ideal Weight Calculator computes ideal bodyweight (IBW) ranges based on height, gender, and age. The idea of finding the IBW using a formula has been sought after by many experts for a long time. Currently, there are several popular formulas, and this Calculator provides their results for side-to-side comparisons.

Age

In theory, age shouldn’t be a large determinant of a IBW past the ages of 14-15 for girls and 16-17 for boys, after which most people stop growing. It is actually expected that human males and females to lose 1.5 and 2 inches in height respectively by age 70. It is important to remember that as people age, lean muscle mass decreases and it is easier to accumulate excess body fat. This is a natural process, though it is possible to lessen the effects of aging by adopting various habits such as monitoring diet, exercise, stress, and sleep.

Gender

Generally, females weigh less than males even though they naturally have a higher percentage of body fat. This is because the male body generally has higher muscle mass, and muscle is heavier than fat. Not only that, but women generally have lower bone density. Last but not least, males tend to be taller than females.

Height

The taller the person, the more muscle mass and body fat they have, which results in more weight. A male at a similar height to a female should weigh about 10-20% heavier.

Body Frame Size

Body frame size is another factor that can have a significant impact on the measurement of ideal weight. Body frame size is typically categorized as small, medium, or large boned. It is measured based on the circumference of a person’s wrist in relation to their height, as shown below.

For women:

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

For men:

  • Height over 5′ 5″
    • Small boned = wrist size 5.5″ to 6.5″
    • Medium boned = wrist size 6.5″ to 7.5″
    • Large boned = wrist size over 7.5″

A person who is large boned will naturally weigh more than someone who is small boned, even at the same height, making body frame size a factor that can affect measurements such as IBW and BMI.

Formulas for Finding the Ideal Weight

IBW formulas were developed mainly to facilitate drug dosage calculations. All of the formulas, have the same format of a base weight given a height of 5 feet, with a set weight increment added per inch over the height of 5 feet. For example, if you are a 5’10” male estimating your ideal weight with the Devine formula, you would add (2.3 × 10) kg to 50 kg to get 73 kg, or ~161 lbs.

The formulas differ in the values used based on the research of the scientists involved in their development, and their findings. The Devine formula is the most widely used formula for the measurement of IBW.

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

Invented 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

Similar to the Hamwi Formula, it was originally intended as a basis for medicinal dosages based on weight and height. Over time, the formula became a universal determinant of IBW.

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

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

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