Ideal Body Weight Calculator
Find your optimal healthy target weight range based on scientific medical formulas including Devine, Robinson, Miller, and Hamwi methods.
Understanding Ideal Body Weight (IBW)
Ideal Body Weight (IBW) provides a baseline range of body weight that is considered medically healthy for a person of a given height and gender. IBW calculations are extensively used by medical professionals to determine medication dosages and fluid requirements.
How to Read Your Result
Enter your gender and height in centimetres, then press the calculate button. The calculator shows:
- A recommended healthy weight range: A minimum and maximum weight in kilograms (kg).
- Four formula results: Estimates from the Devine, Robinson, Miller and Hamwi formulas, also in kg.
The formulas do not agree exactly, and that is normal. Look at the range as a whole rather than a single "perfect" number.
Example: A man who is 170 cm tall gets approximately 65.2 kg using Robinson, 65.9 kg using Devine, 66.0 kg using Miller and 66.9 kg using Hamwi. A woman of 170 cm gets approximately 60.8 kg using Robinson, 61.1 kg using Hamwi, 61.4 kg using Devine and 62.5 kg using Miller.
The Four Formulas Behind This Calculator
All four formulas estimate a base weight for someone who is 5 feet (152.4 cm) tall, then add a fixed amount for every extra inch of height. Your height in centimetres is converted to inches first by dividing it by 2.54.
| Formula | Men | Women |
|---|---|---|
| Devine (1974) | 50 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Robinson (1983) | 52 kg + 1.9 kg per inch over 5 ft | 49 kg + 1.7 kg per inch over 5 ft |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft |
| Hamwi (1964) | 106 lb + 6 lb per inch over 5 ft | 100 lb + 5 lb per inch over 5 ft |
These formulas were not designed to establish personal health targets. They are used in some clinical settings, including certain medication-dosing calculations. A 2023 paper examining variability in ideal body weight formulas found that the formulas can produce different estimates and cautioned against treating them as interchangeable.
Why We Show a Range
Because the formulas can differ by a kilogram or two, showing a range is more useful than presenting one number as the perfect weight. It can also help to compare this estimate with the BMI-based healthy weight range.
For an adult who is 170 cm tall, a BMI of 18.5 to 24.9 corresponds to approximately 53.5 to 72.0 kg. The ideal body weight estimates above fall within this broader range. Both measures can be useful, but neither tells the whole story about a person's health.
You can also check your BMI using our BMI Calculator.
What These Formulas Cannot Tell You
- Body composition: Muscle weighs more than fat for the same volume, so an athlete may weigh more than the estimated range and still be healthy.
- Frame size and age: People with smaller or larger frames, and older adults, may fall outside the range without necessarily having a health problem.
- Height limitations: These formulas count inches above 5 feet. Estimates for adults shorter than about 152 cm may be less reliable.
- Age and pregnancy: These estimates are intended for adults, not children or teenagers, and should not be used to set weight targets during pregnancy.
- Overall health: Energy, strength, sleep, blood pressure, blood sugar and waist size matter too.
- South Asian adults: Some South Asian populations may experience weight-related health risks at lower BMI values than standard international cut-offs suggest. Ask your healthcare professional which measurements are appropriate for you.
How to Use Your Result
Treat your result as a rough reference point, not a deadline. If your weight is above the estimated range, focus on gradual, sustainable changes rather than a quick fix.
Explore our Calorie Calculator to estimate your daily calorie needs, try a no-equipment home workout to get moving, or use the 2-minute rule to help build a consistent habit.
If you are below the estimated range and are losing weight without trying, speak to a healthcare professional.
Frequently Asked Questions
Que.1 What is ideal body weight?Ans. Ideal body weight (IBW) is an estimate calculated using a person's height and sex. It provides a general reference point, rather than an exact measurement of a healthy weight for every individual.
Que.2 Which ideal body weight formula is the most accurate?Ans. No single formula is clearly the best for everyone. Devine, Robinson, Miller and Hamwi were developed for different purposes and can produce slightly different estimates. That is why this calculator displays all four results.
Que.3 Is ideal weight the same as healthy weight?Ans. Not exactly. A healthy weight depends on several factors, including body composition, age and overall health. Ideal body weight formulas provide estimates, not a complete assessment of health.
Que.4 Why is my result different from my BMI range?Ans. BMI uses a broader weight range based on height, whereas ideal body weight formulas estimate a narrower target. They measure different things and should not be treated as interchangeable.
Que.5 Do men and women get different results?Ans. Yes. These formulas use different baseline weights and, in some cases, different adjustment values for men and women at the same height.
Que.6 Can I use this calculator if I am very short or very tall?Ans. The estimates are based on formulas developed around a height of 5 feet and adjustments for additional inches. Results may be less reliable for adults outside the height ranges for which these formulas are commonly used.
Medical Disclaimer
This calculator provides general estimates for adults and is not a substitute for medical advice, diagnosis or treatment. If you have a medical condition, take medication, are pregnant, or plan a significant change in your diet or exercise routine, consult a qualified healthcare professional.