Ideal Weight Calculator

The Ideal Weight Calculator computes ideal body weight (IBW) ranges based on height, gender, and age using several well-known formulas. The idea of finding IBW using a formula has been sought after by many experts for a long time. Currently, there persist several popular formulas, and our calculator provides their results side by side for easy comparison.

How Much Should I Weigh?

Most everyone has at some point tried to lose weight, or at least known somebody who has. This is largely due to the perception of an "ideal" body weight, which is often based on what we see promoted through various media. Although ideal body weight (IBW) today is sometimes based on perceived visual appeal, IBW was actually introduced to estimate dosages for medical use, and the formulas that calculate it are not related to how a person looks at a given weight.

Note that IBW is not a perfect measurement. It does not consider the percentages of body fat and muscle in a person's body. This means that it is possible for highly fit, healthy athletes to be considered overweight based on their IBW. IBW should be considered with the perspective that it is an imperfect measure and not necessarily indicative of health or a weight that a person should necessarily strive toward.

Factors Affecting Ideal Weight

Age — In theory, age shouldn't be a large determinant of IBW past the ages of 14–15 for girls and 16–17 for boys. It is expected that human males and females lose height by age 70. As people age, lean muscle mass decreases and it is easier to accumulate excess body fat.

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.

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 with significant impact on ideal weight. Frame size is typically categorised as small, medium, or large boned based on the circumference of a person's wrist relative to their height.

• For women under 5'2": Small < 5.5" wrist; Medium 5.5"–5.75"; Large > 5.75"
• For women 5'2"–5'5": Small < 6"; Medium 6"–6.25"; Large > 6.25"
• For women over 5'5": Small < 6.25"; Medium 6.25"–6.5"; Large > 6.5"
• For men over 5'5": Small 5.5"–6.5" wrist; Medium 6.5"–7.5"; Large > 7.5"

Formulas for Finding the Ideal Weight

IBW formulas were developed mainly to facilitate drug dosage calculations. All the formulas share the same format: a base weight given a height of 5 feet with a set weight increment added per inch over 5 feet.

Healthy BMI Range — The World Health Organization (WHO) recommends a healthy BMI of 18.5–25 for both males and females. Based on this range it is possible to find a healthy weight for any given height. BMI is widely used in the medical field as a quick indicator of possible health complications.

Limitations of the IBW Calculator

There are limitations to all the formulas and methods. Because the formulas are designed to be applicable to as wide a range of people as possible, they cannot be highly accurate for every single individual. The formulas factor only height and gender, with no considerations for physical handicaps, activity levels, or muscle mass to body fat ratios. Our Ideal Weight Calculator is meant to be used as a general guideline, and its results are not intended as strict values a person must achieve.

IBW Formula Comparison

Formula	Year	Base (Male / Female)	Increment / inch
Hamwi	1964	48.0 kg / 45.5 kg	2.7 / 2.2 kg
Devine	1974	50.0 kg / 45.5 kg	2.3 / 2.3 kg
Robinson	1983	52.0 kg / 49.0 kg	1.9 / 1.7 kg
Miller	1983	56.2 kg / 53.1 kg	1.41 / 1.36 kg