Why "Ideal Weight" Is Complicated
The concept of an ideal body weight has fascinated doctors, scientists, and the general public for well over a century. While it seems like a straightforward question — what should a person of a given height weigh? — the reality is far more nuanced. Human bodies vary enormously in bone density, muscle mass, fat distribution, and genetic predisposition, meaning that no single number can accurately represent the ideal weight for every person of a given height. Two people who are the same height can have vastly different healthy weight ranges depending on their body composition and frame size.
Despite these limitations, ideal weight formulas remain useful tools for establishing a general target range. They provide a starting point for setting health and fitness goals, and they can be particularly helpful for people who are just beginning their weight management journey. The key is to use these formulas as guidelines rather than absolute rules, always considering your individual body composition, activity level, and overall health markers when determining what a healthy weight means for you.
The Devine Formula (1974)
The Devine formula, developed by Dr. B.J. Devine in 1974, was originally created for calculating medication dosages based on body weight. It quickly became one of the most widely used ideal weight formulas in clinical settings and remains popular today. The formula is simple, easy to calculate, and provides results that align reasonably well with general health guidelines for most people.
The Formula
Men:Ideal Body Weight (kg) = 50 + 2.3 × (height in inches − 60)
Women:Ideal Body Weight (kg) = 45.5 + 2.3 × (height in inches − 60)
For example, a man who is 5 feet 10 inches tall (70 inches) would have an ideal body weight of 50 + 2.3 × (70 − 60) = 50 + 23 = 73 kg, or approximately 161 pounds. The formula assumes a baseline weight for a 5-foot-tall person and adds 2.3 kg for each additional inch of height. While the Devine formula works reasonably well for average-height individuals, it tends to underestimate ideal weight for taller people and overestimate it for shorter individuals.
The Robinson Formula (1983)
Dr. J.D. Robinson modified the Devine formula in 1983 to address some of its perceived inaccuracies. Robinson's adjustment changed the baseline weights and the increment per inch of height, resulting in ideal body weight estimates that are slightly lower than the Devine formula for most people. The Robinson formula is considered by some clinicians to produce more realistic estimates, particularly for women, though the differences between the two formulas are generally modest.
The Formula
Men:Ideal Body Weight (kg) = 52 + 1.9 × (height in inches − 60)
Women:Ideal Body Weight (kg) = 49 + 1.7 × (height in inches − 60)
Using the same example of a 5-foot 10-inch man, the Robinson formula yields 52 + 1.9 × 10 = 52 + 19 = 71 kg, or about 157 pounds. This is approximately 2 kg less than the Devine estimate, reflecting the more conservative weight increments built into Robinson's modification. For a practical comparison of all these formulas, our Ideal Weight Calculator computes results from multiple formulas side by side.
The Miller Formula (1983)
Also published in 1983, the Miller formula was developed by Dr. D.C. Miller as another refinement of the original Devine approach. Miller argued that the Devine formula's weight increments per inch of height were too large, and his formula uses smaller increments to produce what he considered more medically appropriate ideal body weights. The Miller formula tends to give the lowest estimates among the commonly used formulas, which some critics argue makes it less suitable for individuals with larger frame sizes or greater muscle mass.
The Formula
Men:Ideal Body Weight (kg) = 56.2 + 1.41 × (height in inches − 60)
Women:Ideal Body Weight (kg) = 53.1 + 1.36 × (height in inches − 60)
For the 5-foot 10-inch man, the Miller formula gives 56.2 + 1.41 × 10 = 56.2 + 14.1 = 70.3 kg, or roughly 155 pounds. As you can see, the four formulas produce a range of approximately 155 to 161 pounds for this individual, which is a relatively narrow spread. This consistency across formulas provides some confidence that the general range is reasonable, though individual variation still plays a significant role.
The Hamwi Formula (1964)
Dr. G.J. Hamwi introduced his ideal body weight formula in 1964, and it became a staple in clinical nutrition and dietetics. The Hamwi formula is unique in that it provides specific adjustments for body frame size, making it somewhat more personalized than the other formulas. It also uses slightly different baseline weights and height increments, resulting in estimates that tend to fall between the Devine and Robinson formulas for most people.
The Formula
Men: Ideal Body Weight = 48.0 kg + 2.7 kg for each inch over 5 feet
Women: Ideal Body Weight = 45.5 kg + 2.2 kg for each inch over 5 feet
Frame Size Adjustments
- Small frame: Subtract 10% from the calculated ideal weight
- Medium frame: Use the calculated ideal weight as-is
- Large frame: Add 10% to the calculated ideal weight
The frame size adjustment is a distinctive feature of the Hamwi formula that acknowledges that people of the same height can have different skeletal structures. A person with a large frame naturally carries more weight than someone with a small frame, even at the same body fat percentage. This adjustment can make a meaningful difference, as a 10% modification on a 70 kg ideal weight shifts the range by 7 kg in either direction.
BMI-Based Approach
An alternative to the traditional ideal weight formulas is to use Body Mass Index (BMI) as a foundation. The World Health Organization defines a healthy BMI range as 18.5 to 24.9 for adults. By calculating the weight range that corresponds to a healthy BMI for your specific height, you can establish an ideal weight range that is grounded in widely accepted health standards. This approach has the advantage of being directly linked to health outcomes rather than arbitrary baseline weights.
To find your BMI-based ideal weight range, you can rearrange the BMI formula. For a person who is 1.78 meters tall, the lower bound of healthy weight would be 18.5 × (1.78)² = 18.5 × 3.1684 = 58.6 kg, and the upper bound would be 24.9 × 3.1684 = 78.9 kg. This gives a healthy weight range of approximately 129 to 174 pounds. This wide range reflects the reality that healthy bodies come in many different sizes. For more on BMI, check our BMI Calculator.
Understanding Body Frame Size
Body frame size is an often-overlooked factor in determining ideal weight, yet it can significantly influence what a healthy weight looks like for you as an individual. Frame size refers to the size and density of your skeletal structure, including the breadth of your shoulders, the width of your wrists, and the circumference of your elbows. People with larger frames naturally weigh more than those with smaller frames at the same height and body fat percentage, because bone is denser than many people realize and contributes meaningfully to total body weight.
A simple method for estimating your frame size involves measuring the circumference of your wrist. For men, a wrist circumference below 6.5 inches suggests a small frame, 6.5 to 7.5 inches indicates a medium frame, and above 7.5 inches suggests a large frame. For women, below 5.5 inches is small, 5.5 to 6.5 inches is medium, and above 6.5 inches is large. While this method is not perfectly precise, it provides a reasonable approximation that can help you contextualize the ideal weight estimates provided by the various formulas.
Why Muscle Mass Matters
One of the most significant limitations of all ideal weight formulas is that they cannot account for muscle mass. Muscle tissue is significantly denser than fat tissue, meaning that a pound of muscle takes up roughly 15-20% less volume than a pound of fat. A person who strength trains regularly and carries substantial muscle mass may weigh well above their calculated ideal weight while maintaining a lean, healthy physique with low body fat.
This is why bodybuilders, athletes, and fitness enthusiasts often find ideal weight formulas misleading. A football player who is 6 feet tall and weighs 220 pounds would be classified as overweight by most formulas and BMI charts, yet may have only 10-12% body fat. For these individuals, body fat percentage and visual assessment are far more meaningful metrics than weight alone. If you are significantly more muscular than average, consider using body composition measurements instead of ideal weight formulas to assess your health and progress. Our Body Fat Calculator can provide a more accurate picture for muscular individuals.
Limitations of Ideal Weight Formulas
It is important to understand the inherent limitations of ideal weight formulas before relying on them too heavily. These formulas were developed primarily using data from Caucasian populations in the mid-20th century, and they may not be equally applicable to all ethnic groups. Research has shown that people of different ethnic backgrounds may have different body compositions and health risk profiles at the same weight and height, which means that the ideal weight for one population group may not be ideal for another.
Additionally, ideal weight formulas do not account for age-related changes in body composition. As people age, they naturally lose muscle mass and bone density while gaining body fat, even if their weight remains stable. This means that an older adult at their calculated ideal weight may have a significantly different body composition than a younger adult at the same weight. For older adults, maintaining strength and physical function through resistance training is often more important than achieving a specific number on the scale.
Finding Your Personal Healthy Weight
Rather than fixating on a single ideal weight number, a more productive approach is to establish a healthy weight range that takes into account your unique body characteristics, lifestyle, and health markers. Start by calculating your ideal weight using several formulas to get a general range, then adjust that range based on your frame size, muscle mass, and how you actually look and feel at different weights. Pay attention to practical indicators like your energy levels, sleep quality, physical performance, and results from routine blood work.
Remember that the scale is only one metric among many, and it does not capture the full picture of your health. A person who weighs slightly above their ideal weight but exercises regularly, eats a nutritious diet, and has normal blood pressure and cholesterol levels is far healthier than someone at their "ideal" weight who is sedentary and eats poorly. Focus on building sustainable habits that support overall wellness rather than chasing a specific number on the scale. The best weight for you is the one that allows you to feel strong, energized, and healthy in your daily life.
Key Takeaways
- Multiple ideal weight formulas exist, including Devine, Robinson, Miller, and Hamwi, each producing slightly different estimates.
- The Hamwi formula is unique in providing frame size adjustments of plus or minus 10% for small and large frames.
- A BMI-based approach using the healthy range of 18.5-24.9 provides a wide but scientifically grounded weight target.
- None of these formulas account for muscle mass, making them less useful for athletes and individuals who strength train.
- Ideal weight formulas were developed primarily using data from Caucasian populations and may not apply equally to all ethnic groups.
- The most effective approach combines formula-based estimates with personal health markers, body composition measurements, and how you actually feel.
Frequently Asked Questions
Which ideal weight formula is the most accurate?
No single formula is universally the most accurate. The Devine formula is the most widely used in clinical settings, while the Hamwi formula offers frame size adjustments that make it more personalized. The best approach is to calculate your ideal weight using multiple formulas and look at the range they produce rather than relying on any single result.
Why do different formulas give different results?
Different formulas use different baseline weights for the 5-foot mark and different increments per additional inch of height. These variations reflect different assumptions about what constitutes a "normal" body composition. The discrepancies are usually modest — typically 5-10 pounds for most people — and the range they create is more useful than any single number.
Should I aim for the exact number the formula gives me?
No. Ideal weight formulas provide estimates, not prescriptions. Your actual healthy weight may be several pounds above or below the calculated value depending on your muscle mass, frame size, and individual health profile. Use the formulas as a general guide and prioritize how you feel, your physical performance, and your overall health markers over hitting a specific number.
Do these formulas work for athletes?
Ideal weight formulas are not well-suited for athletes or anyone with significantly above-average muscle mass. Because these formulas are based on height alone and cannot distinguish between muscle and fat, they tend to classify muscular individuals as overweight or obese. Athletes are better served by tracking body fat percentage and performance metrics rather than weight-based formulas.