Ideal Weight Calculator
Estimate your ideal body weight range from height and sex using four standard IBW formulas.
Calculation Examples
How to Calculate Ideal Body Weight?
Enter your age, sex, and height, choose metric or imperial units, and click "Calculate." The tool applies four formulas: Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). Each is a straight-line equation that starts from a base weight at 5 ft (152.4 cm) and adds a fixed amount for every extra inch. Clinicians use them mainly for drug dosing and rough nutrition planning.
The four formulas themselves do not use age. Treat the result as a reference range, not a diagnosis or a medical target.
The Science Behind IBW Formulas
The four formulas were built for different jobs. Hamwi (1964) was designed for dietary planning in diabetes care, while Devine (1974), Robinson (1983), and Miller (1983) were designed to estimate drug doses. None was validated as a health target, and none accounts for muscle mass, body fat, or activity level, so a bodybuilder and a sedentary person of the same height get the same number. Devine for men, for example, is \(\text{IBW (kg)} = 50 + 2.3 \times (h - 60)\), where \(h\) is height in inches.
For a 170 cm man (6.9 inches over 5 ft), the four formulas give 66.7 kg (Hamwi), 65.9 kg (Devine), 65.2 kg (Robinson), and 66.0 kg (Miller). For comparison, the WHO healthy BMI range for adults is 18.5 to 24.9, which at 170 cm is 53.5 to 72.0 kg. Frame size, judged by wrist circumference, shifts a practical target by roughly 10% in either direction. This tool is informational and not medical advice. Talk to a doctor or registered dietitian before making health decisions.
Useful Tips 💡
- Measure your wrist circumference to find your frame size (small, medium, or large) and adjust the result by roughly 10% up or down.
- Look at the range, not one number. The four formulas were derived separately, and the gap grows with height: at 185 cm, men range from 74.3 kg to 82.7 kg, a spread of 8.4 kg.
- Pair IBW with waist circumference and BMI. A single weight number says little about body composition or health risk.
📋Steps to Calculate
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Enter your age, sex, and height.
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Select units (kg/cm or lbs/inches).
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Click "Calculate" to view your ideal weight range across all four formulas.
Mistakes to Avoid ⚠️
- Treating IBW as a goal for athletes or muscular people. Muscle is denser than fat, so a lean, muscular person often weighs more than the formula result and is still healthy.
- Ignoring frame size. A person with a large frame carries more lean mass and can be healthy above the unadjusted formula result.
- Using the formulas below 5 ft (152.4 cm), where they were designed to start, or for very tall people, where the straight-line model has not been tested well.
- Reading IBW as a health verdict. The formulas were built for dosing and diet planning, not to define who is healthy.
Practical Applications📊
Drug dosing: clinicians use IBW, most often the Devine formula, to dose weight-based drugs such as aminoglycoside antibiotics. For a 175 cm man, Devine gives 70.5 kg.
Setting a reference range: compare your current weight with all four results. At 170 cm, men get 65.2 to 66.7 kg and women get 60.7 to 62.5 kg.
Cross-checking with BMI: IBW and BMI answer different questions. The WHO healthy BMI range of 18.5 to 24.9 is wider, 53.5 to 72.0 kg at 170 cm. Use our BMI Calculator for that view.