Target Weight Calculator

There is no single perfect answer, but several medical formulas — including Devine, Robinson, Miller, and Hamwi — estimate ideal body weight based on height and sex. A healthy BMI range of 18.5–24.9 also provides a useful weight window. These are guidelines, not absolute targets, and individual factors like muscle mass, bone density, and age matter too.

All four formulas estimate ideal body weight from height and sex, but they were developed in different decades and for different clinical purposes. Devine (1974) was originally created for drug dosing, while Robinson (1983) and Miller (1983) were later refinements. Hamwi (1964) is one of the oldest and uses a simpler rule-of-thumb approach. Because each formula gives slightly different results, comparing them gives a more realistic range.

For a 5′4″ (162.6 cm) female, the Devine formula suggests approximately 54.5 kg, while the healthy BMI range (18.5–24.9) corresponds to roughly 55–74 kg. The ideal weight varies by formula and individual health factors, so this range is a starting point rather than a strict target.

Body Mass Index (BMI) is a ratio of weight to height squared. A BMI between 18.5 and 24.9 is considered healthy for most adults. It is widely used because it requires only two easy measurements, but it has limitations — it does not distinguish between fat mass and muscle mass, and may be less accurate for athletes, older adults, or different ethnic groups.

BMI does not account for body composition, distribution of fat, sex differences in fat vs. muscle, or ethnicity. A muscular athlete may register as 'overweight' despite having low body fat, while someone with a normal BMI may still carry excess visceral fat. Health professionals recommend using BMI alongside other measures such as waist-to-hip ratio and body fat percentage.

If you have significant muscle mass, standard formula-based ideal weights and BMI ranges may underestimate your healthy weight. In these cases, body fat percentage is a better indicator. Athletes and highly muscular individuals should consult a healthcare professional for a more personalised assessment.

Most classic formulas (Devine, Robinson, Hamwi, Miller) do not factor in age directly. However, body composition naturally changes with age — older adults tend to lose muscle and gain fat even at the same weight. Some health guidelines suggest slightly higher acceptable weight ranges for adults over 65, though this remains debated among researchers.

A safe and sustainable rate of weight loss is generally 0.5–1 kg per week, achieved through a moderate calorie deficit and regular physical activity. Losing weight faster than this can lead to muscle loss, nutrient deficiencies, and rebound weight gain. Always consult a doctor or registered dietitian before starting a significant weight loss programme.