Ideal Weight Calculator - 4 Formulas + Average

There is no single "ideal" weight that applies to everyone at a given height, which is why this ideal weight calculator presents results from four widely referenced clinical formulas: Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964).

Reviewed by: CalcMojo Editorial Team

Each formula uses a different approach to estimate a healthy weight for your height and sex, and together they provide a practical range rather than a single number.

These formulas were originally developed for clinical applications, particularly for calculating medication dosages based on ideal body weight, and have since become standard references in general health assessment. The Devine formula is the most widely used in pharmacy and medicine, while the Robinson formula is considered by many clinicians to provide the most realistic estimates for the general population.

Enter your height and sex, and the calculator returns four ideal weight estimates along with an overall recommended range. This gives you a realistic weight target grounded in clinical research rather than arbitrary aesthetics. Keep in mind that these formulas do not account for body composition, frame size, or age, all of which affect what constitutes a healthy weight for any individual. For a more comprehensive assessment, pair this tool with our BMI Calculator and Body Fat Calculator.

The Four Ideal Weight Formulas

Each of the four formulas in this calculator was developed by researchers or clinicians for specific medical or pharmacological purposes. They all follow the same basic structure: a base weight for a height of 5 feet (60 inches), plus an incremental amount for each additional inch of height. The formulas differ in their base values and increments, producing a range of estimates.

Devine Formula (1974). Developed by Dr. B.J. Devine for use in calculating drug dosages:

Men: 50.0 + 2.3 kg per inch over 5 feet
Women: 45.5 + 2.3 kg per inch over 5 feet

The Devine formula is the most widely used in clinical pharmacy and is the basis for most drug dosing calculations that reference ideal body weight. It tends to produce lower estimates, particularly for taller individuals.

Robinson Formula (1983). Published by Robinson et al. as a refinement of the Devine formula:

Men: 52.0 + 1.9 kg per inch over 5 feet
Women: 49.0 + 1.7 kg per inch over 5 feet

The Robinson formula generally produces moderate estimates and is often considered the most balanced for general population use. The smaller per-inch increment means it does not penalize taller individuals as much as some other formulas.

Miller Formula (1983). Published by Miller et al. in the American Journal of Hospital Pharmacy:

Men: 56.2 + 1.41 kg per inch over 5 feet
Women: 53.1 + 1.36 kg per inch over 5 feet

The Miller formula produces the highest base values but the smallest per-inch increments. It tends to produce higher ideal weight estimates at shorter heights and lower estimates at very tall heights compared to the Devine formula.

Hamwi Formula (1964). The oldest formula, developed by Dr. George Hamwi:

Men: 48.0 + 2.7 kg per inch over 5 feet
Women: 45.5 + 2.2 kg per inch over 5 feet

The Hamwi formula has the largest per-inch increment for men, making it produce the highest estimates at taller heights. It remains widely referenced in nutrition counseling and dietetics.

Why Multiple Formulas Matter

No single ideal weight formula is definitively correct. Each was derived from different datasets, different clinical contexts, and different populations. By presenting all four, this calculator gives you a range that is more useful than any single estimate.

For a 5-foot-8-inch man, the four formulas produce the following ideal weight estimates:

Devine: 72.6 kg (160 lbs)
Robinson: 67.2 kg (148 lbs)
Miller: 67.5 kg (149 lbs)
Hamwi: 69.6 kg (153 lbs)

The range of 148-160 lbs provides a more realistic target zone than any single number. Where you fall within that range depends on your body composition, frame size, muscle mass, and personal health goals.

For a 5-foot-5-inch woman, the estimates are:

Devine: 57.0 kg (126 lbs)
Robinson: 57.5 kg (127 lbs)
Miller: 59.9 kg (132 lbs)
Hamwi: 56.6 kg (125 lbs)

The tighter range of 125-132 lbs reflects the fact that the formulas agree more closely for heights closer to 5 feet, where the base values dominate over the per-inch increments.

Limitations of Ideal Weight Formulas

While clinically useful, these formulas have significant limitations that every user should understand.

No body composition adjustment. A muscular individual will weigh more than these formulas predict and still be perfectly healthy. A 5-foot-10 man who weight trains regularly might weigh 185 pounds with 12% body fat, well above the formula estimates of 155-166 pounds but in excellent health. Conversely, a sedentary person at the formula-predicted weight might have a high body fat percentage and poor metabolic health.

No frame size adjustment. People come in different skeletal frame sizes. A person with a large frame (wider shoulders, thicker bones) will naturally and healthily weigh more than someone with a small frame at the same height. The traditional method for estimating frame size uses wrist circumference: a wrist circumference above 7.5 inches for men or 6.5 inches for women at medium height suggests a large frame.

No age adjustment. Body composition changes with age. Older adults may have different optimal weight ranges than younger adults, and the maintenance of lean muscle mass becomes increasingly important with age.

Developed from specific populations. These formulas were primarily derived from data on Western, predominantly white populations. They may not produce equally appropriate estimates for individuals of other ethnic backgrounds, particularly given documented differences in body frame size and composition across populations.

How to Use Your Ideal Weight Range

Your ideal weight should be viewed as a reference range, not a rigid target. Here is a practical framework for using this information:

Step 1: Identify your range. Use the four-formula range from this calculator as a starting reference point.

Step 2: Adjust for body composition. If you carry significant muscle mass from regular resistance training, your healthy weight may be 10-20% above the formula estimates. Use our Body Fat Calculator to assess whether your weight is proportionately lean tissue or fat.

Step 3: Consider your BMI. Check your BMI using our BMI Calculator. A BMI of 18.5-24.9 combined with a body fat percentage in the healthy range and good metabolic markers (blood pressure, blood sugar, cholesterol) is a more comprehensive indicator of healthy weight than any formula alone.

Step 4: Focus on health markers, not just weight. Blood pressure, fasting blood glucose, lipid panel, waist circumference, and physical fitness level are all more direct indicators of health than body weight. A person who weighs slightly above their formula range but exercises regularly, eats well, and has excellent metabolic health is in better shape than someone at the formula weight who is sedentary with poor nutrition.

Step 5: Set realistic goals. If you are currently above your ideal range and want to lose weight, aim for 0.5-1 pound per week using a moderate calorie deficit. Calculate your deficit with our Calorie Deficit Calculator. Drastic weight loss attempts rarely produce lasting results and often lead to muscle loss and metabolic adaptation.

Ideal Weight in Medical Context

In clinical medicine, ideal body weight (IBW) calculations serve purposes beyond general health assessment. Understanding these applications helps explain why these formulas exist and why they are structured the way they are.

Drug dosing. Many medications, particularly antibiotics, chemotherapy agents, and anesthetics, are dosed based on ideal body weight rather than actual body weight. This is because drug distribution in adipose tissue differs from distribution in lean tissue, and dosing based on total weight in obese patients can lead to overdosing. The Devine formula is the standard reference for this application.

Tidal volume in mechanical ventilation. For patients on ventilators, tidal volume is calculated based on ideal body weight to prevent lung injury. Using actual body weight in obese patients would result in excessive tidal volumes and potential lung damage.

Nutrition assessment. Dietitians use IBW to set initial calorie and protein targets for hospitalized patients, then adjust based on clinical response. The ratio of actual body weight to IBW helps classify the degree of overweight or underweight.

These medical applications underscore that the formulas were designed for specific clinical purposes and were not intended to define a single "correct" weight for every individual in the general population.

This calculator provides general estimates based on published formulas. It is not medical advice and does not replace consultation with a qualified healthcare provider.

Frequently Asked Questions

Which ideal weight formula is the most accurate?

No single formula is definitively most accurate because ideal weight depends on individual factors like body composition, frame size, and age that these formulas do not capture. The Robinson formula is often considered the most balanced for general population estimates. The Devine formula is the standard in clinical pharmacy. Using all four together provides a practical range.

Why is my ideal weight different from what I expected?

Ideal weight formulas produce estimates based on population averages and do not account for muscle mass, frame size, or body composition. If you exercise regularly and carry above-average muscle, your healthy weight may be higher than formula estimates. Conversely, if you are sedentary, your healthy weight might be at the lower end of the range. Use body fat percentage for more individual assessment.

Is ideal body weight the same as healthy weight?

Not necessarily. Ideal body weight formulas provide reference values based on height and sex, but healthy weight is determined by a combination of factors including body composition, metabolic health markers, physical fitness, and overall well-being. A person slightly above their formula ideal weight with excellent metabolic health is healthier than someone at the formula weight with poor metabolic markers.

How does frame size affect ideal weight?

People with larger skeletal frames naturally weigh more due to heavier bones and the ability to carry more muscle. A large-framed individual may be perfectly healthy at a weight 10-15% above formula estimates. You can estimate frame size by measuring wrist circumference. Large frames are indicated by wrist circumference above 7.5 inches for men or 6.5 inches for women at medium height.

Should I use ideal weight or BMI to set my goal?

Use both as reference points, but prioritize body fat percentage and metabolic health markers. BMI provides a general category (underweight, normal, overweight, obese), while ideal weight formulas give specific weight targets. Neither accounts for body composition. A weight within the normal BMI range that also falls near your ideal weight range is a reasonable starting target.

Do ideal weight formulas work for athletes?

These formulas significantly underestimate healthy weight for athletes and regular exercisers with above-average muscle mass. A competitive athlete may weigh 15-30% more than formula predictions and be in excellent health. Athletes should rely on body fat percentage and performance metrics rather than ideal weight formulas.

How much should my weight change as I age?

Some weight gain with age is normal due to changes in body composition, hormonal shifts, and reduced activity. However, research suggests that maintaining a relatively stable weight through middle age is associated with better health outcomes. Focus on preserving lean muscle mass through resistance training and adequate protein rather than targeting a specific weight number.

Sources & Methodology

Devine BJ, "Gentamicin therapy," Drug Intelligence and Clinical Pharmacy, 1974.
Robinson JD et al., "Determination of ideal body weight for drug dosage calculations," American Journal of Hospital Pharmacy, 1983.
Miller DR et al., "Ideal body weight calculation," American Journal of Hospital Pharmacy, 1983.
Hamwi GJ, "Therapy: Changing dietary concepts," in Diabetes Mellitus: Diagnosis and Treatment, American Diabetes Association, 1964.
Frame size assessment methodology from Metropolitan Life Insurance Company height-weight tables and associated wrist circumference guidelines.

Default values shown are illustrative. Always verify with your healthcare provider. Data accurate as of: March 2026