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. The Devine formula is the most commonly referenced in clinical literature, appearing in over 18,000 published studies according to a review in the Annals of Pharmacotherapy. All four formulas share the same linear structure: a base weight for someone 5 feet tall plus additional weight for each inch above 5 feet. 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. The National Institutes of Health recommends using IBW as part of a comprehensive assessment rather than a standalone measure.

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 (161 lbs). The same man's Robinson IBW would be 52 + (1.9 × 10) = 71 kg, Miller IBW would be 56.2 + (1.41 × 10) = 70.3 kg, and Hamwi IBW would be 48 + (2.7 × 10) = 75 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. A newer approach, the Peterson equation (2016), uses the formula IBW = 2.2 × BMI + 3.5 × BMI × (height in meters - 1.5), which may be more accurate for people at the extremes of the height range.

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 — it is the default IBW formula in most hospital electronic health record systems. 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 and diabetes management, as it was originally developed for estimating caloric needs in diabetic patients. A 2017 study in the journal Nutrition in Clinical Practice compared all four formulas against healthy BMI ranges and found that the Devine formula overestimated ideal weight for shorter individuals and underestimated it for taller individuals, while the Miller formula was the most consistent across height ranges for women. 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 and used earlier actuarial tables. The Devine formula (1974) was developed for internal medicine drug dosing, specifically for calculating aminoglycoside antibiotic doses, and quickly became the default in clinical practice. Robinson and Miller (both 1983) refined earlier estimates using Metropolitan Life Insurance height-weight tables from different years (1959 and 1983, respectively), with Miller incorporating data from a broader population sample. For a 5'10" male, the difference between the lowest (Miller: 70.3 kg) and highest (Hamwi: 75.0 kg) formula estimate is 4.7 kg, or about 6.7%. For shorter and taller individuals, the discrepancies can be even larger — up to 14% for men and 19% for women at extreme heights — because the per-inch increment differences compound over more inches. This variability is precisely why presenting all four results together gives a more honest and useful picture than any single formula.

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 such as blood pressure, fasting glucose, and cholesterol. The CDC emphasizes that health risk is more closely tied to body fat distribution (especially visceral fat around organs) than to total body weight. Use the ideal weight as a reference point, but focus on health indicators rather than hitting an exact number. If your blood work is normal, you exercise regularly, and you feel energetic at your current weight, you may be at your personal healthy weight even if it differs from the formula estimate by several kilograms.

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 (a condition known as sarcopenia), while body fat percentage tends to increase even if total weight remains stable. By age 70, the average person has lost roughly 25–30% of their peak muscle mass. Some research, including a widely cited 2014 study in the American Journal of Clinical Nutrition covering over 197,000 adults, 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. This phenomenon, sometimes called the "obesity paradox" in the elderly, may be because modest fat reserves provide metabolic protection during acute illness. For older adults, maintaining muscle mass through resistance training two to three times per week and consuming adequate protein (1.0–1.2 g per kg of body weight daily, according to the European Society for Clinical Nutrition) 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. A 2005 study in the American Journal of Health-System Pharmacy found that the Devine formula significantly overestimated ideal weight for individuals under 5 feet and underestimated it for those over 6 feet 2 inches. 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, the formulas may underestimate healthy weight by 5–15 kg due to greater muscle mass. For elderly individuals, the formulas may overestimate healthy weight due to age-related muscle loss. For individuals of Asian descent, the formulas may overestimate ideal weight since health risks increase at lower BMI thresholds. These calculators serve as useful starting points that should always be interpreted alongside body-composition data and clinical health markers.

The World Health Organization defines a healthy BMI as 18.5–24.9 for adults. This range was established based on large epidemiological studies showing that mortality and morbidity rates are lowest within this band. In some Asian countries, including South Korea, Japan, and China, a stricter range of 18.5–22.9 is used because research demonstrates that Asian populations develop type 2 diabetes, hypertension, and cardiovascular disease at lower BMI values — a phenomenon attributed to higher proportions of visceral fat at equivalent BMI levels. To find your healthy weight range in kilograms, multiply the BMI limits by your height in meters squared. For example, for someone 170 cm (5'7") tall: minimum = 18.5 × 1.7² = 53.5 kg (118 lbs), maximum = 24.9 × 1.7² = 71.9 kg (159 lbs). This 18.4 kg (41 lb) range is considerably wider than the spread produced by the four IBW formulas, which better accounts for natural body type variation including differences in bone density, muscle mass, and body frame size.

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 below 120/80 mmHg, fasting blood sugar below 100 mg/dL, total cholesterol below 200 mg/dL, and triglycerides below 150 mg/dL). Small fluctuations of 1–3 kg (2–7 lbs) are completely normal due to water retention, meal timing, glycogen stores, and hormonal changes — women may experience fluctuations of up to 2–4 kg during their menstrual cycle. According to the National Weight Control Registry, people who maintain long-term weight loss typically weigh themselves once a week and focus on trend lines rather than daily numbers. 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, which can mean a difference of 6–8 kg (13–18 lbs) in either direction. 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 (16.5–19 cm), 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 (14–16.5 cm), and large is over 6.5 inches (16.5 cm). Another method uses elbow breadth: extend your arm forward, bend your forearm to 90 degrees, and measure the distance between the two bony protrusions of your elbow with a caliper. The original Metropolitan Life Insurance tables (1983) included separate columns for small, medium, and large frames, with weight differences of up to 15 kg (33 lbs) between small and large frames at the same height. 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. If you are unsure of your frame size, using the average of all four formula results provides a reasonable middle estimate.