How this ideal weight calculator works
Ideal body weight (IBW) is an estimate of a healthy weight for a person of a given height and sex. The classic formulas — Devine, Robinson, Miller and Hamwi — were developed decades ago, originally to help with medical dosing, and they all share the same simple structure: a base weight at a height of 5 feet (152.4 cm), plus a fixed amount of weight for every inch above that.
Because every formula uses only your height and sex, none of them account for muscle mass, frame size or body composition. They also disagree with one another, which is exactly why this tool shows all four side by side. As a more modern complement, it also shows the healthy BMI weight range — the span of weights that puts your body mass index between 18.5 and 24.9 for your height, calculated as weight = BMI × height in metres squared.
Reference note: imperial height is converted before the formula runs — total inches are multiplied by 2.54 to get centimetres, and the formulas work in inches over 60. Kilogram results are multiplied by 2.2046 to show pounds, and values are rounded for display.
The four formulas at a glance
Each gives ideal weight in kg from height in inches over 5 feet (60 in):
| Formula | Men | Women |
|---|---|---|
| Devine | 50 + 2.3 × (in over 60) | 45.5 + 2.3 × (in over 60) |
| Robinson | 52 + 1.9 × (in over 60) | 49 + 1.7 × (in over 60) |
| Miller | 56.2 + 1.41 × (in over 60) | 53.1 + 1.36 × (in over 60) |
| Hamwi | 48 + 2.7 × (in over 60) | 45.5 + 2.2 × (in over 60) |
Frequently asked questions
- What is ideal body weight?
- Ideal body weight (IBW) is an estimate of a healthy weight for a person of a given height and sex. It comes from simple height-based formulas originally developed for medical dosing, not from any single perfect number, so treat it as a rough reference point rather than a target you must hit exactly.
- Which ideal weight formula is best?
- No single formula is definitively best. Devine is the most widely used in clinical settings, while Robinson, Miller and Hamwi are refinements that give slightly different numbers. Because they all rely only on height and sex, it is most useful to look at the range they produce together rather than trusting any one value.
- How is ideal weight calculated?
- Each formula starts from a base weight at a height of 5 feet (152.4 cm) and adds a fixed amount per inch above that. For example, Devine uses 50 kg for men plus 2.3 kg per inch over 5 feet, and 45.5 kg for women plus 2.3 kg per inch. We convert your height to inches, apply each formula, and show the result in both kg and lb.
- Is ideal weight accurate for athletes or very muscular people?
- No. Ideal weight formulas use only height and sex, so they ignore muscle mass, bone structure and body composition. A muscular athlete can weigh well above their formula-based ideal weight while being very lean and healthy, so these numbers are not meaningful for that group.
- Ideal weight vs a healthy BMI range — which should I use?
- A healthy BMI range (BMI 18.5 to 24.9) gives a span of weights for your height rather than a single figure, which better reflects that healthy bodies come in a range of sizes. For most people the BMI range is a more practical, modern guide, and we show it alongside the formula results for context.
- Should I consult a professional about my weight?
- Yes. This calculator is informational only and is not medical advice, diagnosis or treatment. Healthy weight depends on many factors these formulas cannot capture, so for guidance tailored to your body and health, speak with a qualified doctor or dietitian.