Ideal Weight Calculator
Estimate your ideal body weight using the Devine, Robinson, Miller, and Hamwi formulas.
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How the Ideal Weight Calculator Works
Our ideal weight calculator estimates your ideal body weight (IBW) using four well-known formulas: Devine, Robinson, Miller, and Hamwi. Each was developed to provide a healthy weight reference for a given height and gender. The calculator also shows the healthy weight range based on a BMI of 18.5–24.9.
The Four Formulas
All four formulas use a base weight for 5 feet (152.4 cm) and add a fixed amount for each inch above that. The key difference is the base and the per-inch adjustment, which vary by formula and gender:
- Devine (1974): Men — 50 kg + 2.3 kg per inch over 5 ft. Women — 45.5 kg + 2.3 kg per inch.
- Robinson (1983): Men — 52 kg + 1.9 kg per inch over 5 ft. Women — 49 kg + 1.7 kg per inch.
- Miller (1983): Men — 56.2 kg + 1.41 kg per inch over 5 ft. Women — 53.1 kg + 1.36 kg per inch.
- Hamwi (1964): Men — 48 kg + 2.7 kg per inch over 5 ft. Women — 45.5 kg + 2.2 kg per inch.
For a 175 cm (about 5'9") man, the Devine formula gives 50 + 2.3 × 9 ≈ 70.7 kg. The other formulas produce slightly different results, which is why this calculator shows all four and an average.
Healthy Weight Range (BMI)
In addition to the four IBW formulas, the calculator shows the weight range corresponding to a BMI of 18.5–24.9, which the World Health Organization defines as a healthy weight. This range is calculated as 18.5 × height² to 24.9 × height² (in meters). For 175 cm, that's about 56.6 kg to 76.3 kg — a broader and more flexible target than any single IBW number.
Limitations of Ideal Body Weight
The IBW formulas were originally developed for clinical purposes such as drug dosing and nutritional assessment. They do not account for muscle mass, bone density, age, or body composition. A heavily muscled athlete may weigh well above their IBW while being extremely healthy, while someone with low muscle mass may be at their IBW but metabolically unhealthy. Use IBW as one reference point alongside BMI, body fat percentage, and how you feel.
Which Formula Is Best?
There is no universally best formula. The Devine formula is the most widely used in clinical settings and medical references. Robinson and Miller were developed later as refinements. Hamwi is often used for medium-frame adults. Because the formulas give slightly different results, the average shown in the results gives you a balanced single number, while the range from all four plus the BMI range gives you a healthy target zone.
Tips for Using This Calculator
- Use the average of the four formulas as a general target, not a strict rule.
- Compare your IBW to the BMI healthy range for a more flexible target zone.
- Consider body composition — muscle weighs more than fat, so muscular people may exceed IBW.
- Focus on sustainable habits rather than hitting an exact number.
- Consult a healthcare professional for personalized guidance.
Frequently Asked Questions
Ideal body weight (IBW) is an estimate of the weight that is associated with the lowest mortality risk for a given height and gender. It was originally developed for clinical use, such as drug dosing, but is commonly used as a general health reference.
There is no single best formula. The Devine formula is the most widely used in clinical settings. Robinson and Miller are common alternatives. Hamwi is often used for medium-frame adults. This calculator shows all four so you can compare and use the range as a guide.
Each formula was developed using different populations and assumptions about body composition. They all use height above 5 feet as a base but apply different weight adjustments per inch. The differences are typically small, and a healthy weight range spans several kilograms.
No. The formulas do not account for muscle mass, bone structure, age, or body composition. Very muscular individuals may weigh more than their IBW while being perfectly healthy. Use IBW as a general guide alongside BMI and body fat percentage for a fuller picture.