Ideal Weight Calculator

Ideal body weight or IBW is the normal, healthy weight for your age, sex, and height, that ensures the least risk of metabolic disorders and mortality. It is determined by several variables, and different mathematical formulas have been introduced to give you a rough estimate of how much you should weigh.





In this article, we discuss how an online ideal weight calculator works, its accuracy, and its limitations. We then share some tips on weight loss and improving lean muscle mass to help you achieve good health.

Ideal Body Weight IBW Calculator

Weight is an important determinant of your health. Being underweight is associated with severe malabsorption, nutrient deficit, and consequent health complications. At the same time, overweight and obese individuals have a higher risk of metabolic syndrome, cardiovascular disease, and even death.

Ideal weight is essentially the weight associated with minimum health risks. IBW calculator is a useful tool that estimates your healthy weight.

Formulas To Calculate Ideal Body Weight

Calculating ideal weight is complex because it involves several factors that are not yet included in a comprehensive equation. However, certain formulas have been developed to give you a rough idea of IBW.

Following are the formulas your ideal weight calculator is based on:

Robinson’s Ideal Body Weight Formula

For Men

52 kg + 1.9 kg per inch over 5 feet

For Women

49 kg + 1.7 kg per inch over 5 feet

Devine Ideal Weight Formula

For Men

50.0 kg + 2.3 kg per inch over 5 feet

For Women

45.5 kg + 2.3 kg per inch over 5 feet

Miller Ideal Weight Formula

For Men

56.2 kg + 1.41 kg per inch over 5 feet

For Women

53.1 kg + 1.36 kg per inch over 5 feet

Hamwi Ideal Weight Formula

For Men

48.0 kg + 2.7 kg per inch over 5 feet

For Women

45.5 kg + 2.2 kg per inch over 5 feet

Body Mass Index

Body mass index BMI, is one of the most reliable ways to estimate normal weight.

BMI is the ratio of your weight (in kg) to your height (in m2).

BMI = weight (kg) / height (m2)

This weight-to-height ratio or BMI, is then categorized into four types according to the World Health Organization:

  • < 18.5 = underweight
  • 18.5 to < 25 = healthy BMI range
  • 25 to < 30 = overweight
  • 30 or higher = obese

It is important to mention that the above classification is applicable to people over the age of 20.

For a child’s BMI (above two years of age) and that of young adults, instead of BMI classification, growth or height weight chart is used. These charts or graphs have calibrated percentiles. When you plot weight and height on the chart, it corresponds with a BMI percentile, which explains your health.

Here are different BMI percentiles and their relative BMI category:

  • < 5% = underweight
  • 5% to 85% = healthy
  • 85% to 95% = overweight
  • > 95% = obese

You can use an online body mass index calculator to check your body mass index.

Factors Affecting Ideal Body Weight

Here are all the major factors affecting ideal body weight:


Age is one of the most important factors affecting ideal body weight. Although you might think a person stops growing once they are fully developed (which is between the ages of 14 to 15 for girls and 16 to 17 for boys), height and body composition fluctuate throughout your life.

As you age, your bones reduce in linear length due to friction at the level of joints. This friction results from loss of lubricating and protective cartilage.

This reduction in bone length, in addition to the loss of lean muscle mass, causes you to lose almost one centimeter per decade after you hit 40. This loss of height becomes more rapid and significant in your 70s.

Another important sign of aging is the loss of muscle mass, which leads to a rapid rise in body fat. This is why older adults and seniors are prone to obesity if a balanced diet and active lifestyle are not ensured.

With the change in height, and increase in body fat, your energy requirements decrease, which implies a reduced ideal body weight. This can also be explained by the fact that body fat percentage is associated with a high risk of metabolic diseases, blood pressure, and cardiovascular disease.

Gender, Muscle Mass, and Body Fat Percentage

Body composition and fat distribution vary with gender, which is why ideal weight formulas are calibrated differently for men and women.

Men have higher muscle mass than women. Muscle mass primarily comes from proteins, which are metabolized at a faster rate than fats. Additionally, proteins also need more energy to be metabolized (in other words, it has a higher thermic effect) than that body fat.

Both these factors increase total daily energy expenditure, which raises calorie requirements in men. This is why their ideal body weight is higher.

In contrast with men, women have more body fat and lower lean muscle mass. In addition to that, the metabolism of macronutrients, especially fats, is slower, which allows fat tissue to accumulate in the body for a long time.

Apart from this, the fat distribution also varies for both genders. Where men tend to have fat around the trunk and abdomen, women are more likely to have fat deposition around the hips and thighs.

There are varying health conditions associated with fat tissue in different areas, which explains different ideal body weight formulas based on gender, even for men and women of the same height and age.


Understandably, height is directly related to normal weight. A tall person has more body surface, requires more energy, and thus, has a higher ideal body weight as compared to someone of short stature.

Additionally, at any given height, the organ size also varies from person-to-person. For a large boned individual, IBW would measure than that of a small boned person, due to higher calorie requirement.

Waist Circumference

Waist size is one of the most crucial defining factors of ideal body weight.

Excess body fat mostly deposits around the waist, which is why increased midsection weight poses a high risk of developing metabolic diseases, hypertension, heart disease, diabetes, high blood cholesterol, etc.

Other than that, weight loss and gain also become significant with variations in waist size, which is why it is often considered better than the BMI scale.

Waist Size For Men

Here’s the risk of metabolic diseases in men corresponding to different waist circumferences:

  • < 94 cm or 37 in – low risk
  • 94 cm to 102 cm or 37 to 40 in – high risk
  • > 102 cm or 40 in – very high risk

Waist Size for Women

Here’s the risk of metabolic disorders in women relative to their waist size:

  • < 80 cm or 31.5 in – low risk
  • 80 cm to 88 cm or 31.5 into 34.6 in – high risk
  • > 88cm – very high risk

Body Frame Size

Body frame size depicts your wrist circumference in relation to your height. It is determined by the bone size and density, which is important for ideal body weight calculations.

Frame Size For Women

Here’s the frame size classification for women of different heights:

Height < 5’2”

  • Small = wrist size < 5.5 in
  • Medium = wrist size 5.5 into 5.75 in
  • Large = wrist size over 5.75 in

Height 5’2” to 5’5”

  • Small = wrist size < 6 in
  • Medium = wrist size six into 6.25 in
  • Large = wrist size over 6.25 in

Height > 5’5”

  • Small = wrist size < 6.25 in
  • Medium = wrist size 6.25 into 6.5 in
  • Large = wrist size > 6.5 in

Frame Size For Men

For men, frame size classification is based on height measuring more than 5’5″.

Height more than 5’5”

  • Small boned = wrist size 5.5 into 6.5 in
  • Medium boned = wrist size 6.5 into 7.5 in
  • Large boned = wrist size >7.5 in

Activity Level

Physical activity is another crucial factor affecting the metabolic rate and hence, the ideal body weight.

If your nature of work is intense, or you engage in strenuous exercises, your body burns calories at a higher rate and in more amounts than someone who has a sedentary /inactive lifestyle.

Hence, your required daily calorie intake would be higher than an average individual, which automatically increases your ideal body weight.

In nutrition sciences, physical activity is divided into different levels based on the type and frequency of exercise. However, unfortunately, they are not taken into account when calculating ideal body weight.

Limitations Of Ideal Weight Calculator

The ideal Body weight calculator does not give accurate results and only approximates your healthy weight. This is because the formulas have certain limitations:

  • Not considering a physical activity for ideal weight is one of the biggest loopholes of the calculator. Even the BMI range is uncertain and inaccurate in certain cases because physical activity has a huge impact on metabolic rate.

An athlete having more muscles might be categorized as overweight in terms of body mass index, even when they are perfectly healthy.

  • From the discussion on factors affecting ideal weight, we know how critical waist circumference and frame size are. Not including them in formulas affects the results.
  • Body mass index classification is based on data collected from white men. Although the exact science of how genetic variations affect metabolism is unclear, data suggest that metabolic rate and energy expenditure vary for each race. Some groups naturally have an efficient metabolism and, thus, different ideal body weights.

For a more accurate idea of ideal weight, things like waist circumference and weight scales can be considered a BMI alternative. Apart from that, DEXA, which is considered the gold standard for body measurement according to body composition, can also be used for IBW.

Health Effects Of Obesity

Ideal body weight calculators are mostly used to lose weight. Before we get to weight loss tips, let’s first go through the health complications of obesity.

  • Hypertension (high blood pressure)
  • Hypercholesterolemia (high cholesterol)
  • Increased risk of constriction /obstruction in coronary arteries due to fat deposits)
  • Type 2 diabetes
  • Stroke
  • Gallbladder disease
  • Sleep apnea
  • Impairment of functions of vital organs like the liver and kidneys

Due to unhealthy practices and an inactive lifestyle, obesity is a major problem and the leading cause of death, especially in the developed world.

Healthy Ways To Lose Weight

When it comes to sustainable weight loss. You should know that fasting for long hours and having elaborate workout sessions is not the right way to go.

Counting your calories and total daily energy expenditure (TDEE) are the first step to make a weight loss meal plan.

Daily calorie intake depends on your energy requirement which is determined by the total number of calories your body burns in a day. A TDEE calculator can be used to estimate these values.

Afterwards, if you want to lose weight, your daily calorie intake should be less than total daily energy expenditure, as this allows your body to burn and utilize fat tissue.

You can also consider following IIFYM or If It Fits Your Macros diet plan. This is based on tracking the macros (proteins, carbs, fats) instead of completely restricting their intake.

Here’s how many calories each of these macronutrients produce after breakdown:

1 gm protein = 4 calories

1 gm carbs = 4 calories

1 gm fats = 9 calories

Considering this, if you want to lose weight, your diet should have minimal fat.

When planning your weight loss meal, it is also crucial to remember that a healthy diet should include adequate quantities of all three macros, i.e., 45 to 65% carbs, 10 to 35% proteins and 20 to 35% fats.

If you are aiming to drop significant number of pounds, getting an expert consultation is better to reduce possible risks associated with nutrient and energy deficit. You can also discuss getting a prescription for certain drugs that help with weight loss.

You can also consider getting a physical trainer for weight loss exercises.

Other than that, general healthy habits like minimal alcohol intake, eating good calories, and maintaining an active lifestyle also goes a long way.