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BMI Calculator
Calculate your Body Mass Index instantly.
Ideal Weight Calculator
Calculate your ideal body weight range using four evidence-based formulas: BMI range, Hamwi, Devine, and Robinson. Supports metric and imperial, and shows results for both male and female.
cm
How to use the Ideal Weight Calculator
Choose metric or imperial
Select metric (cm) or imperial (feet and inches) for your height input.
Select your sex
The formulas produce different results for males and females, reflecting differences in typical body composition.
Enter your height
Type your height accurately. Results are most useful when height is precise — even 1 cm can shift the result by up to 2 kg.
Review all four estimates
The calculator shows results from three clinical formulas (Hamwi, Devine, Robinson) plus the healthy BMI weight range. The average gives a reasonable middle ground.
About this Ideal Weight Calculator
'Ideal weight' is a concept that sounds simple but has significant nuance in practice. The formulas used by this calculator were not designed for general fitness advice — they were developed for medical applications such as calculating drug doses, anaesthetic amounts, and ventilator settings, where lean body mass matters more than total weight. The Hamwi formula (1964) is the oldest of the three and is still widely used in pharmacy and nutrition. Devine (1974) became the standard for pharmacokinetic calculations. Robinson (1983) was a revision of Devine, producing slightly lower estimates — particularly for women. None of these formulas were validated against large general populations. The BMI-based range (18.5–24.9 kg/m²) comes from the World Health Organisation's classification system. While BMI is frequently criticised for ignoring body composition, the healthy BMI range at least reflects population-level data on disease risk. Its weakness is well-documented: muscular individuals can be classified as 'overweight' while having very low body fat. What does this mean in practice? Use these figures as a rough orientation, not a target. Someone who is physically fit and active at a weight above the 'ideal' calculated here may be in better health than someone sedentary at the calculated ideal weight. Body weight is one health marker among many — consult a healthcare provider for a complete picture.
Frequently Asked Questions
Ideal weight depends on height, sex, and body frame. Several formulas exist — the BMI-based range (18.5–24.9) gives a broad healthy weight window, while clinical formulas like Hamwi and Devine give a single target. Our calculator shows all four so you can see the range of estimates.
For men: 48 kg for the first 152 cm (5 ft), then add 2.7 kg per inch over 5 ft. For women: 45.5 kg for the first 152 cm, then add 2.2 kg per inch over 5 ft. It was developed in 1964 for medical dosing purposes and is still widely used clinically.
No. Men typically have more muscle mass and denser bones, so ideal weight is higher for men at the same height. All four formulas in our calculator (BMI range, Hamwi, Devine, Robinson) produce separate results for male and female.
Ideal weight formulas are guides, not clinical diagnoses. Muscle-heavy individuals (athletes, bodybuilders) will exceed the BMI-based range while having low body fat. Age, ethnicity, and body composition all affect what a healthy weight looks like. Use the results as a starting reference and consult a healthcare professional for personalised advice.
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