Ideal Weight Calculator

Wondering what your ideal weight should be for your height? Our free ideal weight calculator applies four well-established clinical formulas commonly used to estimate your ideal weight in seconds.

Calculate your ideal weight

Enter your details below to see your results, along with an adult healthy BMI range for comparison. (This calculator is intended for adults aged 18 yrs and over and is not suitable for children, teens, pregnant women or for calculating medication doses).

Gender: *

Biological sex is required because men and women have different baseline muscle mass and bone density ratios.

Stand up straight without shoes for the most accurate measurement.

Results output

Here are your estimated weights across the four clinical formulas.

Robinson
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Miller
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Devine
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Hamwi
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Healthy BMI Range
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*Estimates only. See full clinical & legal disclaimer below.

How much should be my weight? Understanding the results

If your first thought is “Why is the number so low?”, you’re not alone. Most people using a weight calculator expect to see an ideal fitness weight. Instead, the result is a clinical estimate based on established medical formulas created for healthcare use.

There isn’t a perfect number that defines your ideal weight. Your muscle mass, bone structure, age, and health history all influence what a healthy weight looks like for you. Rather than aiming for a single figure, it’s more helpful to focus on achieving a weight that supports good overall health, reduces your risk of conditions such as type 2 diabetes and high blood pressure, and allows you to maintain your daily activities with good energy levels.

Think of these four formulas as a guide rather than a final answer. If your result doesn’t seem right or you’re worried about your weight, speaking with a doctor is the best way to get personalized advice.

The 4 clinical formulas behind the calculator

These formulas may look intimidating, but they were developed for a very practical medical purpose. They weren’t designed as weight-loss tools; they were developed to help healthcare professionals calculate medication doses. Some medicines don’t distribute evenly through body fat, so total body weight isn’t always the best guide for dosing.
Formula Year Originally developed for Result tendency
Robinson Formula 1983 Drug dosage calculations (refinement of Devine) Slightly more accurate for taller individuals
Miller Formula 1983 Digoxin dosing Tends to run slightly lower than Robinson
Devine Formula 1974 Gentamicin (antibiotic) dosing Most widely used in clinical practice
Hamwi Formula 1964 Quick dietitian rule-of-thumb Oldest of the four; simplest calculation

Each formula uses different assumptions and equation values. That’s why your four results may vary slightly. Rather than focusing on a single formula as the most accurate, look at the range of estimates they provide together and compare them with the healthy BMI range above.

The myth of the “Perfect weight and height”

It’s tempting to view your calculator as the ideal weight for your height. However, these formulas have limitations. Developed many years ago, they rely mainly on height and sex and don’t account for the natural differences between individuals.

A few key factors these formulas can’t measure:

  • Muscle mass: Muscle is denser than fat, so it weighs more despite taking up less space. As a result, two people of the same height and weight can have very different body fat and muscle levels.
  • Body density and frame size: Some people naturally have a larger skeletal frame, with features such as broader shoulders or wider hips. As a result, they may have a higher healthy weight than a person of the same height with a smaller frame.
  • Age: Body composition changes naturally with age, including changes in muscle mass and fat distribution. Most weight formulas don’t account for these age-related changes.
Because of these limitations, an ideal weight calculator should be used as a guide, not a target to chase. If you’re working towards weight loss or improving your fitness, a doctor or dietitian can provide personalised advice that takes into account your body composition, frame size, age, and overall health.

BMI healthy range vs. ideal body weight

While your ideal weight result provides a single estimate, the adult healthy BMI range in your results (generally 18.5 to 24.9 for non-pregnant adults) offers a more practical guide as it reflects a healthy range rather than a single target.

The ideal body weight formula gives a single estimate based on your height and sex. A healthy BMI range, however, offers greater flexibility. It usually spans around 10 to 15 kilograms (but may be outside this range for some heights), reflecting that healthy bodies come in different shapes and sizes.

For most adults, aiming to stay within the healthy BMI range is generally a more practical and sustainable approach than trying to reach one specific ideal body weight. If you have questions about results, a doctor can assess them alongside your age, body composition, and overall health.

Limitations of measuring body mass index

Body mass index (BMI) is a simple and widely used screening tool, but it has some limitations. Since it’s based only on height and weight, it cannot differentiate between muscle and fat. This means muscular individuals may be classified as overweight even when they have low body fat.

BMI also doesn’t take into account where body fat is stored. Growing evidence indicates that waist circumference and fat distribution are also important in assessing the risk of metabolic conditions.

Although BMI is a useful screening tool, it doesn’t take into account factors such as age, sex, ethnicity or pregnancy. In addition, adult BMI categories aren’t designed for children or teenagers. That’s why BMI is best viewed as one part of an overall health assessment rather than a stand-alone diagnostic tool. Waist circumference and clinical assessment may also be needed to understand health risk.

Ideal weight FAQs

How much must I weigh for my height?

There’s no one “correct” ideal weight. Different formulas estimate it in slightly different ways. Our calculator provides estimates using the Devine, Robinson, Miller and Hamwi formulas, along with a healthy BMI range. This offers a more balanced guide, as muscle mass, body frame and age also influence your healthy weight.
A preferred weight-for-height calculator estimates a healthy body weight based on your height and biological sex. The clinical formulas it uses were originally designed for medical purposes, including medication dosing, rather than to set weight-loss or fitness goals.
Ideal body weight formulas were developed decades ago for clinical dosing calculations, not to set fitness or weight-loss goals. As a result, the estimated weight is often lower than people expect. They also don’t distinguish between muscle and fat, so people with a muscular or athletic build may receive a result that’s lower than their healthy body weight.
While traditional ideal body weight formulas don’t account for age, healthy weight isn’t the same throughout life. Natural changes in body composition mean it’s common to weigh slightly more in your 50s and later than in your 20s.
Body fat percentage often provides a more complete picture of your body composition than ideal body weight alone because it reflects the proportion of muscle and fat in your body. While ideal weight calculators help estimate a healthy body weight, they should be used alongside other tools, including BMI and waist circumference.
Frame size is often estimated using wrist circumference relative to height, though methods vary. For a more accurate assessment, a doctor or dietitian can evaluate your body frame as part of your overall health rather than relying on a simple self-measurement.
There’s no single ideal weight for older women, as healthy weight ranges vary with age, muscle mass, and individual health history. The healthy BMI range (18.5-24.9) is usually a more useful guide than a single ideal body weight figure, especially for older adults.
dr-nelson-lau

Medically reviewed by

MBBS, FRACGP, General Practitioner, 30+ Years of Experience

General Medical Disclaimer (Mandatory):

Estimates only. This ideal weight calculator uses legacy clinical formulas (Devine, Robinson, Miller, Hamwi) to provide an estimate based on population averages. Because it relies only on height and sex, it cannot account for individual variations in muscle mass, bone density, or age. This tool does not provide medical advice, diagnosis, or medication-dosing instructions. Always consult a registered GP or healthcare professional regarding your health, weight goals, and diet.

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