Ideal Weight Calculator

Ideal body weight (IBW) is a clinically estimated weight range based on a person's height and gender. It was originally developed in the 1960s–1970s for medical purposes such as calculating drug dosages and ventilator settings. Today, four main formulas are used: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each produces slightly different estimates because they were developed from different population data. IBW is best understood as a reference range rather than a single target number, and should be considered alongside other health metrics like BMI, body fat percentage, and waist circumference.

All four major IBW formulas share the same basic structure: a base weight for someone who is 5 feet (152.4 cm) tall, plus an additional amount for each inch above 5 feet. For example, the Devine formula calculates men's IBW as 50 kg + 2.3 kg for each inch over 5 feet, and women's as 45.5 kg + 2.3 kg per inch over 5 feet. A 5'10" man would have a Devine IBW of 50 + (2.3 × 10) = 73 kg. The formulas differ in their base weights and per-inch increments, producing a range of estimates that typically spans 5–10 kg for any given height.

No single formula is universally the most accurate. The Devine formula is the most widely used in clinical settings, particularly for drug dosing and respiratory care. The Robinson and Miller formulas use more recent Metropolitan Life Insurance data from 1983 and tend to produce slightly more moderate estimates. The Hamwi formula is often used in nutrition counseling. For the best estimate, consider the average of all four formulas along with the healthy BMI range (18.5–24.9), which accounts for the natural variation in body types. A newer approach, the Peterson equation, uses a target BMI to calculate ideal weight and may be more accurate across different heights.

The formulas give different results because they were developed at different times using different study populations and clinical goals. The Hamwi formula (1964) was created for estimating caloric needs in diabetic patients. The Devine formula (1974) was developed for internal medicine drug dosing. Robinson and Miller (both 1983) refined earlier estimates using Metropolitan Life Insurance height-weight tables from different years (1959 and 1983, respectively). For a 5'10" male, the difference between the lowest and highest formula estimate can be up to 14%, or roughly 5–7 kg (11–15 lbs).

Not exactly. 'Ideal weight' from these formulas is a single estimate based only on height and gender. 'Healthy weight' is a broader concept — the WHO defines it as a BMI range of 18.5–24.9, which for a 5'10" person spans from 58.6 to 77.1 kg (129–170 lbs). Your ideal weight estimate will fall somewhere within this healthy range. A person can be healthy at many different weights within this range, depending on their body composition, fitness level, and overall health markers. Use the ideal weight as a reference point, but focus on health indicators rather than hitting an exact number.

Yes, although none of the four standard formulas account for age. Body composition changes naturally with aging: adults typically lose 3–8% of muscle mass per decade after age 30 (sarcopenia), while body fat percentage tends to increase. Some research suggests that slightly higher BMI values (23–27) may be associated with lower mortality in adults over 65, compared to the standard 18.5–24.9 range for younger adults. For older adults, maintaining muscle mass through strength training and adequate protein intake is often more important than achieving a specific weight target.

Ideal weight calculators provide reasonable estimates for the general population but have significant limitations for individuals. Studies show that the four formulas can differ by up to 14% for men and 19% for women at the same height. The formulas only use height and gender, ignoring crucial factors like muscle mass, body frame size, age, ethnicity, and body fat distribution. They are most accurate for average-build adults of medium frame between 5'0" and 6'2". For athletes, elderly individuals, or those with unusual body compositions, these calculators serve as rough starting points rather than precise targets.

The World Health Organization defines a healthy BMI as 18.5–24.9 for adults. In some Asian countries, including South Korea, a stricter range of 18.5–22.9 is used because research shows that Asian populations face increased health risks at lower BMI values. To find your healthy weight range in kilograms, multiply the BMI limits by your height in meters squared. For example, for someone 170 cm tall: minimum = 18.5 × 1.7² = 53.5 kg, maximum = 24.9 × 1.7² = 71.9 kg. This provides a broader range than individual formulas and better accounts for natural body type variation.

No — it is more practical and healthier to aim for a weight range rather than an exact number. The four formulas produce a spread of estimates, and the healthy BMI range provides an even wider target zone. Focus on maintaining a weight where you feel energetic, can perform daily activities comfortably, and have healthy metabolic markers (blood pressure, blood sugar, cholesterol). Small fluctuations of 1–3 kg are normal due to water retention, meal timing, and hormonal changes. If your weight is within the healthy BMI range and your health markers are good, you are likely at a healthy weight regardless of what the formulas say.

Body frame size significantly impacts what constitutes a healthy weight. The Hamwi formula recommends adjusting ideal weight by ±10% for large or small frames. You can estimate your frame size by measuring your wrist circumference: for men, a small frame is under 6.5 inches (16.5 cm), medium is 6.5–7.5 inches, and large is over 7.5 inches (19 cm); for women, a small frame is under 5.5 inches (14 cm), medium is 5.5–6.5 inches, and large is over 6.5 inches (16.5 cm). A large-framed person may weigh 10% more than the formula estimate and still be at a healthy weight, while a small-framed person's ideal weight may be 10% lower.