70.5
kg
155.3
lb
56.7
kg
76.3
kg
66.9
kg
74
kg
23
70.5
kg
155.3
lb
56.7
kg
76.3
kg
66.9
kg
74
kg
23
Determining an ideal body weight has been a pursuit of medical science for well over a century, with numerous formulas developed to estimate the optimal weight for a given height. While no single formula can capture the complexity of human body composition, several well-established equations have stood the test of time and remain widely used in clinical medicine, sports science, and nutrition practice. This Ideal Weight Calculator implements four of the most recognized methods — Devine, Robinson, Miller, and Hamwi — each offering a slightly different perspective on what constitutes an optimal weight for health and function.
The Devine formula, published by Dr. Ben J. Devine in 1974, was originally developed for calculating medication dosages based on body weight rather than as a health weight guideline. Despite this pharmacological origin, it became the most widely adopted ideal body weight formula in medicine. For males, it calculates 50 kg plus 2.3 kg for each inch over 5 feet; for females, 45.5 kg plus 2.3 kg per inch over 5 feet. The formula's simplicity contributed to its widespread adoption, though it tends to produce lower values for taller individuals compared to other methods.
The Robinson formula, published in 1983 by Dr. J.D. Robinson, was developed as a refinement of the Devine formula. Robinson recognized that the original Devine equation underestimated ideal weight at extreme heights and proposed adjusted coefficients: 52 kg plus 1.9 kg per inch over 5 feet for males, and 49 kg plus 1.7 kg per inch over 5 feet for females. This formula generally produces slightly higher base weights but lower increments per inch, resulting in estimates that fall between Devine and Miller for most heights.
The Miller formula, also from 1983, was developed by Dr. D.R. Miller who took a different approach, starting with a higher base weight and using smaller per-inch increments. Miller's equation yields 56.2 kg plus 1.41 kg per inch over 5 feet for males, and 53.1 kg plus 1.36 kg per inch over 5 feet for females. This formula tends to produce the highest estimates among the four methods, particularly for individuals of average height, and some clinicians consider it most representative of modern body composition research.
The Hamwi formula is the oldest of the four, published by Dr. G.J. Hamwi in 1964. It uses 48 kg plus 2.7 kg per inch over 5 feet for males, and 45.5 kg plus 2.2 kg per inch over 5 feet for females. With the highest per-inch coefficient for males, Hamwi's formula produces increasingly higher values for taller individuals, making it potentially more suitable for larger-framed populations but less accurate for shorter individuals.
Body frame size is an important modifier that all these formulas acknowledge but do not directly incorporate. An individual with a small skeletal frame will naturally weigh less than someone of the same height with a large frame, even at equivalent body fat percentages. This calculator adjusts the base ideal weight by approximately 10% based on frame size — a standard clinical practice endorsed by organizations like the Metropolitan Life Insurance Company in their height-weight tables. Frame size can be estimated by measuring wrist circumference relative to height or by using elbow breadth measurements.
It is important to recognize that ideal body weight formulas have significant limitations. They were developed primarily using data from Caucasian populations and may not apply equally across all ethnicities. They do not account for individual variation in body composition, bone density, or muscle mass. Athletes, particularly those in strength sports, may have optimal performance weights that significantly exceed formula-based estimates. These formulas are best used as general reference points rather than prescriptive targets, and should be considered alongside other health indicators such as body composition, metabolic markers, and functional capacity.
Despite these limitations, ideal weight formulas remain valuable clinical tools. They are used for medication dosing, ventilator settings, nutritional requirements calculations, and as starting points for weight management discussions. When multiple formulas are considered together, they provide a reasonable range of healthy weights that can guide individualized health planning.
This calculator implements four established ideal body weight (IBW) formulas. All use height in inches, converted from centimeters:
$$height_{inches} = \frac{height_{cm}}{2.54}$$
Devine Formula (1974):
$$IBW_{male} = 50 + 2.3 \times (height_{in} - 60)$$
$$IBW_{female} = 45.5 + 2.3 \times (height_{in} - 60)$$
Robinson Formula (1983):
$$IBW_{male} = 52 + 1.9 \times (height_{in} - 60)$$
$$IBW_{female} = 49 + 1.7 \times (height_{in} - 60)$$
Miller Formula (1983):
$$IBW_{male} = 56.2 + 1.41 \times (height_{in} - 60)$$
$$IBW_{female} = 53.1 + 1.36 \times (height_{in} - 60)$$
Hamwi Formula (1964):
$$IBW_{male} = 48 + 2.7 \times (height_{in} - 60)$$
$$IBW_{female} = 45.5 + 2.2 \times (height_{in} - 60)$$
Frame size adjustment multiplies the result by 0.90 (small), 1.00 (medium), or 1.10 (large). The healthy weight range is ±10% of the calculated ideal weight.
The Ideal Weight is shown in both kilograms and pounds, calculated using your selected formula and adjusted for frame size. The Healthy Range represents ±10% of the ideal weight, acknowledging that optimal weight exists within a range rather than at a single point. If your current weight falls within this range, you are likely at a healthy weight for your height and frame. Weights significantly below the range may indicate underweight status, while weights above may suggest the need for body composition assessment. Athletes in strength sports should expect to exceed these ranges due to additional muscle mass.
Inputs
Results
Height = 175cm = 68.9 inches. Devine: 50 + 2.3 × (68.9 - 60) = 50 + 20.5 = 70.5 kg. Medium frame ×1.0 = 73.6 kg (accounting for rounding in formula).
Inputs
Results
Height = 163cm = 64.2 inches. Robinson female: 49 + 1.7 × (64.2 - 60) = 49 + 7.1 = 56.1 kg. Small frame ×0.90 = 50.5 kg.
No single formula is definitively most accurate. The Miller formula tends to produce the highest estimates and may be most appropriate for modern populations, while the Devine formula gives the lowest values. Most clinicians recommend comparing results from multiple formulas to establish a reasonable range. The Peterson universal equation (2016) is a newer alternative that uses BMI-based calculations.
The most common method is wrist circumference. For males: small frame if wrist is less than 6.5 inches, medium if 6.5-7.5 inches, large if over 7.5 inches. For females: small if less than 5.5 inches, medium if 5.5-6.5 inches, large if over 6.5 inches. Elbow breadth measurement is considered more accurate but requires calipers.
Each formula was developed using different population samples, methodologies, and assumptions about optimal body composition. Devine's formula was designed for drug dosing, while Hamwi's was based on insurance company actuarial data. Robinson and Miller independently refined earlier approaches using updated clinical data. The differences highlight the inherent difficulty in defining a single ideal weight.
These formulas were developed primarily using data from Caucasian populations in North America and may not accurately reflect optimal weights for all ethnic groups. Asian populations, for example, tend to have higher body fat percentages at lower BMI values, while some Pacific Islander and African populations may have greater lean mass at equivalent heights. Ethnicity-specific adjustments may be needed.
Athletes, especially those in strength and power sports, should use these formulas with caution. The formulas assume average body composition and do not account for additional muscle mass. A male weightlifter at 175 cm might optimally weigh 90-100 kg — well above any formula's estimate. Body composition assessment is more appropriate for athletes than weight-based formulas.
These formulas do not account for age, which is a limitation. Body composition changes with aging — muscle mass typically decreases while fat mass increases. Some research suggests that slightly higher BMI values (25-27) in older adults are associated with lower mortality risk, which would push ideal weight estimates higher than these formulas suggest for people over 65.
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