The Ideal Weight Calculator estimates your ideal body weight based on your gender and height using four popular formulas - Robinson, Miller, Devine, and Hamwi - and also shows the healthy weight range for your height based on BMI. Enter your details below and click Calculate.
The ideal weight calculator estimates how much you should weigh based on your height and gender, using the four most widely recognized ideal body weight (IBW) formulas - Robinson, Miller, Devine, and Hamwi - and also displays the healthy weight range for your height derived from the body mass index (BMI). Because each formula was developed in a different context and produces a slightly different result, seeing all four side by side gives you a realistic range rather than a single misleading number. This is exactly how clinicians and nutrition professionals use ideal body weight: as a useful reference point, not an absolute target.
Simply choose US or Metric units, enter your age, gender, and height, and the calculator instantly returns your estimated ideal weight from each formula along with the healthy BMI-based range.
Ideal body weight (IBW) is an estimate of the weight that is considered healthiest for a person of a given height and gender. The concept was originally developed in the medical field - not for cosmetic reasons, but to help doctors calculate medication dosages, assess nutritional status, and set clinical targets. Many drug dosages, particularly for anesthesia and certain medications, are based on ideal body weight rather than actual weight because using actual weight in overweight patients could lead to overdosing.
It is important to understand that ideal body weight is only an estimate. It does not account for body composition (the ratio of muscle to fat), frame size, or individual health factors. A muscular athlete may weigh more than their "ideal" weight yet be perfectly healthy, while someone within their ideal range could still carry unhealthy levels of body fat. For this reason, ideal weight is best viewed as one of several tools - alongside BMI, body fat percentage, and waist circumference - for understanding overall health.
All four formulas in this calculator share the same structure: a base weight assigned at a height of 5 feet (60 inches), plus an additional amount of weight for each inch of height above 5 feet. They differ only in the base value and the per-inch increment, and each has separate values for men and women. The calculator converts your height to inches, applies each formula, and (in US mode) converts the result from kilograms to pounds.
Below are the exact formulas used, with weight in kilograms and height measured in inches over 5 feet:
| Formula | Men | Women |
|---|---|---|
| Robinson (1983) | 52 kg + 1.9 kg per inch over 5 ft | 49 kg + 1.7 kg per inch over 5 ft |
| Miller (1983) | 56.2 kg + 1.41 kg per inch over 5 ft | 53.1 kg + 1.36 kg per inch over 5 ft |
| Devine (1974) | 50.0 kg + 2.3 kg per inch over 5 ft | 45.5 kg + 2.3 kg per inch over 5 ft |
| Hamwi (1964) | 48.0 kg + 2.7 kg per inch over 5 ft | 45.5 kg + 2.2 kg per inch over 5 ft |
Example: For a man who is 5 feet 10 inches tall (10 inches over 5 feet), the Robinson formula gives 52 + 1.9 × 10 = 71 kg (about 156.5 lbs), the Miller formula gives 56.2 + 1.41 × 10 = 70.3 kg (155.0 lbs), the Devine formula gives 50 + 2.3 × 10 = 73 kg (160.9 lbs), and the Hamwi formula gives 48 + 2.7 × 10 = 75 kg (165.3 lbs).
Dr. G.J. Hamwi created the earliest of these formulas in 1964, originally to help estimate the caloric and nutritional needs of patients with diabetes. It assigns a relatively generous per-inch increase, which tends to produce higher ideal weights than the later formulas for tall individuals.
Dr. B.J. Devine introduced his formula in 1974, initially to standardize medication dosing - particularly for certain antibiotics. The Devine formula became the de facto standard in clinical pharmacy and medical practice and remains the most widely used ideal body weight formula in healthcare today, even though it was never validated through large-scale research.
J.D. Robinson published a modification of the Devine formula in 1983, refining the base values and increments to better reflect observed data. The Robinson formula generally produces somewhat lower ideal weights than Devine and Hamwi.
Also published in 1983, the Miller formula by D.R. Miller uses the smallest per-inch increment of the four, meaning the ideal weight rises more gradually with height. It often yields results between the others for average heights.
In addition to the four formulas, the calculator shows the healthy weight range for your height based on BMI. Body mass index is defined as weight in kilograms divided by height in meters squared. A BMI between 18.5 and 25 is generally considered to be in the healthy range for adults, so the calculator multiplies these BMI values by your height squared to produce a weight range:
Healthy Weight Range = 18.5 × height² to 25 × height² (height in meters)
For example, a person 1.8 m (180 cm) tall has a healthy weight range of 18.5 × 1.8² = 59.9 kg to 25 × 1.8² = 81.0 kg. The ideal weights from the four formulas typically fall within this BMI-based range, which is why the range is a helpful sanity check.
Ideal weight formulas rely on only two inputs - height and gender - but a truly healthy weight for any individual depends on several additional factors:
Body composition changes with age. Older adults tend to lose muscle mass and may carry more fat at the same weight, while children and teenagers are still growing and should be assessed using age-and-sex-specific growth charts rather than adult ideal weight formulas. The classic IBW formulas were designed for adults.
On average, women have a higher body fat percentage and less muscle mass than men of the same height, and they tend to have lighter, smaller frames. This is why every ideal weight formula uses different values for men and women.
People with larger bone structures and wider frames naturally weigh more than those with smaller frames at the same height. A common way to gauge frame size is to measure wrist circumference relative to height. Ideal weight formulas assume an average frame, so large-framed people may sit above the calculated value and small-framed people below it - both perfectly healthily.
Muscle is denser than fat, so two people of the same height and weight can look and be very different. A muscular individual may exceed their "ideal" weight and every healthy BMI threshold while carrying very little body fat. This is the single biggest limitation of weight-based metrics, and it is why body fat percentage is a valuable complement.
Where fat is stored matters for health. Fat carried around the abdomen (visceral fat) is associated with higher health risk than fat carried on the hips and thighs, even at the same total weight. Waist circumference and waist-to-hip ratio capture this dimension that weight alone cannot.
The ideal weight formulas are quick, convenient estimates - but they are not precise measurements of health. They were developed decades ago, mostly for clinical dosing rather than for defining personal fitness goals, and they were never rigorously validated against large, diverse populations. Their main weaknesses are that they ignore body composition, frame size, and age, and that they can become less reliable at the extremes of height. For someone of average build and average height, the formulas give a reasonable target; for very tall, very short, very muscular, or very lean individuals, they should be treated with caution.
The best approach is to use ideal weight as one reference among several. Combine it with BMI, body fat percentage, waist measurements, and - most importantly - guidance from a healthcare professional who can consider your full health picture.
If your current weight is far above the range shown, gradual, sustainable change - through balanced nutrition and regular physical activity - is the healthiest path forward. If you are below the range, you may benefit from nutrient-dense foods and strength training to build healthy mass. In either case, modest, consistent changes are more effective and more sustainable than extreme diets. And remember that the number on the scale is just one indicator: how you feel, your energy levels, your fitness, and your lab results all matter at least as much.
Each formula (Robinson, Miller, Devine, and Hamwi) was developed at a different time using slightly different assumptions, so they produce slightly different results. Showing all four gives you a realistic range rather than a single, falsely precise figure. Most people's healthy weight falls somewhere within that spread.
No single formula is definitively "most accurate," but the Devine formula is the most widely used in clinical settings, primarily for medication dosing. For personal use, it is best to consider the range produced by all four formulas together along with the healthy BMI range.
No. The Robinson, Miller, Devine, and Hamwi formulas were designed for adults. Children and teenagers should be assessed using age- and sex-specific growth charts and percentiles provided by a pediatrician, because they are still growing.
Not necessarily. Ideal weight is a guideline, not a strict target. Frame size, muscle mass, and individual health all affect what weight is right for you. A healthy weight is best confirmed with a healthcare professional, considering body composition and overall health rather than a single number.
On average, women have a higher body fat percentage, less muscle mass, and lighter frames than men of the same height. The formulas account for this with separate base weights and per-inch increments for each gender.
The ideal weight formulas give a single estimated weight for your height and gender, while the healthy BMI range gives the span of weights (BMI 18.5 to 25) considered healthy for your height. The formula results usually fall within the BMI range, which serves as a useful cross-check.