How to Calculate Your Ideal Weight

The concept of an ideal body weight has been studied by physicians and researchers for over a century. Several clinical formulas attempt to estimate the weight at which a person of a given height is likely to experience the best health outcomes. While no formula can account for every individual variable, understanding how these calculations work gives you a useful starting point for setting realistic, health-focused weight goals.

This guide explains the four most widely used ideal weight formulas, compares their results side by side, and helps you interpret the numbers in the context of your unique body composition, frame size, and lifestyle. The key takeaway is that your ideal weight is a range, not a single number, and it should serve as a guideline rather than an absolute target.

What Is Ideal Body Weight?

Ideal body weight (IBW) is the weight at which research suggests a person of a given height has the lowest risk of weight-related health complications. It is not meant to define what you should look like or to set an aesthetic standard. Instead, it is a clinical estimate used in healthcare for purposes such as calculating medication dosages, assessing nutritional needs, and establishing baseline weight goals for patients.

The concept originated from insurance company actuarial data in the mid-20th century, when researchers noticed that certain weight ranges for each height correlated with lower mortality rates among policyholders. Over the decades, several researchers refined these estimates into the mathematical formulas used today. Each formula takes height as the primary input and calculates a weight estimate, with different formulas for men and women to account for biological differences in body composition.

It is important to recognize that ideal weight formulas do not account for muscle mass, bone density, body fat distribution, age, ethnicity, or fitness level. A heavily muscled person may weigh significantly more than their calculated ideal weight while being in excellent health. Conversely, someone at their calculated ideal weight but with very low muscle mass and high body fat may face elevated health risks.

The Four Major Ideal Weight Formulas

Four formulas dominate clinical and fitness applications for estimating ideal weight. Each uses height in inches (above 5 feet) as the primary variable and assigns a base weight for 5 feet of height, then adds an increment for each additional inch.

Devine Formula (1974)

The Devine formula is the most widely used in clinical medicine, particularly for calculating drug dosages and tidal volumes in mechanical ventilation. It was not originally intended as a health recommendation but has become a standard reference point.

Robinson Formula (1983)

The Robinson formula was published as a modification to the Devine formula, using updated population data to produce what the authors considered more representative estimates for the general population.

Miller Formula (1983)

Also published in 1983, the Miller formula generally produces higher ideal weight estimates, particularly for taller individuals. It uses a smaller per-inch increment but a higher base weight.

Hamwi Formula (1964)

The Hamwi formula is the oldest of the four and was developed for quick clinical estimation. It uses the simplest increments, making it easy to calculate mentally, which contributed to its widespread adoption before digital calculators became ubiquitous.

Formula Comparison Table

The following table shows ideal weight estimates for men and women at several heights, calculated using all four formulas. Seeing the results side by side illustrates how much the formulas can vary and why averaging them or using a range is more practical than relying on any single formula.

Side-by-Side Results by Height

At 5 feet 10 inches, the four formulas produce a range of 155 to 166 pounds for men and 144 to 150 pounds for women. This 11-pound spread for men and 6-pound spread for women demonstrates why treating ideal weight as a range rather than a fixed number is more practical and more honest about what these formulas can actually tell us.

Real-World Ideal Weight Examples

Example 1: Setting a Realistic Goal

James is 5 feet 11 inches tall and currently weighs 215 pounds. He wants to lose weight and asks his doctor for a target. Running the four formulas gives him ideal weight estimates of 166 (Devine), 160 (Robinson), 158 (Miller), and 172 (Hamwi) pounds. The average is 164 pounds.

His doctor suggests a more gradual approach: aim for 185 pounds first, a 30-pound loss that brings him into a healthier BMI range. Once James reaches 185, he can reassess based on how he feels, his energy levels, and his blood work results. Setting the initial target 20 pounds above the formula average feels more achievable and prevents the discouragement that comes from facing a seemingly impossible goal.

Example 2: Athlete Evaluating Performance Weight

Sofia is a 5-foot-7-inch competitive swimmer weighing 155 pounds. Her ideal weight according to the formula average is approximately 136 pounds. However, Sofia carries significant lean muscle mass from years of training, and her body fat percentage is a healthy 20%. Her performance in the water is strong, and her energy levels are excellent.

In Sofia's case, the ideal weight formulas underestimate her appropriate weight because they do not account for above-average muscle mass. Her coach and nutritionist agree that her current weight supports optimal performance and health. This example highlights why athletes and regular exercisers should evaluate their weight in the context of body composition rather than relying solely on height-based formulas.

Example 3: Postpartum Weight Assessment

Nadia is 5 feet 5 inches tall and weighed 130 pounds before her pregnancy. Nine months after delivery, she weighs 148 pounds. The formula average for her height is approximately 127 pounds. Nadia feels pressure to return to her pre-pregnancy weight quickly.

Her healthcare provider explains that postpartum weight loss is gradual, typically taking 6 to 12 months or longer. Breastfeeding, hormonal changes, sleep deprivation, and the demands of caring for a newborn all affect metabolism and weight management. Rather than fixating on a formula number, Nadia focuses on nourishing her body with balanced meals and resuming moderate exercise when cleared by her doctor. A year later, she reaches 135 pounds and feels healthy and strong.

Factors That Affect Your Ideal Weight

The four standard formulas use only height and sex as inputs, but many other factors influence what weight is truly ideal for you as an individual.

• Body frame size. People with larger bone structures naturally weigh more. A 10% adjustment up or down based on frame size (measured by wrist circumference) can bring formula estimates closer to reality.
• Muscle mass. Muscle is denser than fat, so individuals with above-average muscle mass will weigh more than formulas predict without carrying excess body fat.
• Age. Body composition shifts as you age, with muscle mass declining and fat mass potentially increasing. Older adults may find their optimal weight differs from what formulas calculated during their 20s.
• Ethnicity. Some ethnic groups tend to have different body proportions, bone densities, and fat distribution patterns that formulas developed from predominantly Caucasian populations may not capture accurately.
• Health conditions. Certain medical conditions and medications affect weight. Thyroid disorders, polycystic ovary syndrome, and corticosteroid use can all shift body weight independently of diet and exercise.

Tips for Reaching a Healthy Weight

If your current weight is above the range suggested by these formulas, the following evidence-based strategies can help you move toward a healthier weight safely and sustainably.

• Set incremental goals. Rather than targeting the formula number directly, break your journey into 5% to 10% milestones. Research shows that even a 5% reduction in body weight produces meaningful improvements in blood pressure, blood sugar, and cholesterol.
• Focus on habits, not just the scale. Building sustainable habits like regular meal preparation, consistent exercise, and adequate sleep leads to lasting change. The number on the scale follows when the habits are in place.
• Include strength training. Resistance exercise preserves and builds muscle mass during weight loss, improving your body composition even if the scale moves slowly. Muscle also raises your resting metabolic rate.
• Monitor body composition, not just weight. Use a body fat calculator or waist circumference measurements to track whether you are losing fat specifically, which matters more than total pounds lost.
• Be patient with the process. Sustainable weight loss occurs at a rate of 0.5 to 2 pounds per week. Faster rates increase the risk of muscle loss, nutrient deficiencies, and rebound weight gain.

Common Mistakes to Avoid

• Treating the formula number as gospel. Ideal weight formulas are estimates based on population averages. They do not define what you specifically should weigh. A person 10 pounds above or below their calculated ideal weight can be perfectly healthy depending on their body composition and lifestyle.
• Ignoring body composition entirely. Two people at the same ideal weight can look and feel very different if one has 15% body fat and the other has 30%. Always consider how much of your weight is lean mass versus fat mass.
• Pursuing rapid weight loss. Crash diets and extreme caloric restriction lead to muscle loss, metabolic slowdown, and almost always result in regaining the weight. A moderate, consistent approach produces better long-term results.
• Comparing yourself to others. Your body, genetics, muscle mass, and frame size are unique. Comparing your weight to a friend or celebrity of the same height ignores the countless individual variables that make your ideal weight different from theirs.
• Using only one formula. Any single formula can overestimate or underestimate your ideal weight by 10 pounds or more. Using the average of all four or consulting a BMI-based range gives a more balanced perspective.

Last updated: February 23, 2026