Ideal Weight Calculator
Find your ideal body weight using four proven medical formulas and see your healthy range
Your Ideal Weight Results
Understanding Ideal Body Weight
Ideal body weight (IBW) is a clinical estimate of what a person should weigh based on their height, gender, and body frame. Unlike a single magic number, IBW represents a reference point that physicians, dietitians, and pharmacists use to guide drug dosing, nutritional planning, and health risk assessment. The concept originated in the insurance industry during the 1940s and 1950s, when actuarial data from the Metropolitan Life Insurance Company showed that certain weight ranges were associated with the lowest mortality rates for each height and gender group.
This calculator implements four widely recognized IBW formulas. The Devine formula (1974) was originally created for calculating medication dosages and became the most commonly referenced equation in clinical practice. The Robinson formula (1983) refined Devine's approach using updated population data. The Miller formula (1983) tends to produce slightly higher estimates, reflecting a more lenient view of healthy weight. The Hamwi formula (1964) is one of the oldest and simplest methods, frequently used in clinical dietetics for quick bedside weight estimates.
Frame size plays a meaningful role in determining your ideal weight. A person with a larger skeletal frame naturally carries more bone mass and can support more muscle tissue, which means a higher healthy weight compared to someone of the same height with a smaller frame. The most common way to estimate frame size is by measuring wrist circumference: a male with a wrist circumference under 6.5 inches is considered small-framed, while over 7.5 inches is large-framed. For females, the thresholds are under 5.5 inches and over 6.5 inches respectively.
It is important to remember that ideal weight calculations are general guidelines, not absolute targets. They do not account for individual factors such as muscle mass, body fat distribution, ethnicity, or age-related changes in body composition. Athletes and highly muscular individuals may weigh significantly more than their calculated IBW while being perfectly healthy. Always use these results alongside other health markers like BMI, body fat percentage, waist circumference, and your physician's guidance to form a complete picture of your health.
How to Use This Calculator
- Enter your height using the input field above. Toggle between centimeters and feet/inches using the unit switcher next to the height label.
- Select your gender from the dropdown. The ideal weight formulas use different base values and increments for males and females.
- Choose your body frame size (small, medium, or large). If unsure, select medium. You can estimate your frame by comparing wrist circumference to your height.
- Click "Calculate Ideal Weight" to see your results. The calculator will show the average across all four formulas, your healthy weight range, and your BMI at ideal weight.
- Review the formula comparison chart to see how Robinson, Miller, Devine, and Hamwi results differ, and use the weight range visualization to see where your ideal falls on the healthy spectrum.
Frequently Asked Questions
What is the difference between the four ideal weight formulas?
Each formula was developed by different researchers using different population data. The Devine formula (1974) is the most widely used in clinical settings and was originally designed for drug dosing. The Robinson formula (1983) updated Devine's work with newer data and tends to give slightly lower estimates for women. The Miller formula (1983) generally produces the highest estimates among the four. The Hamwi formula (1964) is the oldest and simplest, commonly used in clinical dietetics. All four calculate ideal weight based on height and gender, using a base weight for the first 5 feet of height plus an increment for each additional inch.
How does frame size affect my ideal weight?
Frame size adjusts the base ideal weight by approximately 10%. A small frame reduces the calculated ideal weight by 10%, reflecting less bone mass and a naturally lighter build. A large frame increases the ideal weight by 10%, accounting for heavier bone structure and the ability to support more lean tissue. Medium frame uses the standard formula values without adjustment. To determine your frame size, measure your wrist circumference: for men, under 6.5 inches is small, 6.5-7.5 inches is medium, and over 7.5 inches is large. For women, the ranges are under 5.5, 5.5-6.5, and over 6.5 inches.
Why do the formulas give different results?
The formulas were developed in different decades using different study populations and methodologies. Devine's formula was created for pharmaceutical dosing, not as a health target. Robinson and Miller updated the approach with 1980s data but used different statistical methods. Hamwi used yet another dataset from the 1960s. The differences are typically small (usually within 2-5 kg of each other), and the average of all four provides a reasonable middle ground. No single formula is considered definitively superior.
Is ideal weight the same as healthy weight?
Not exactly. Ideal body weight is a statistical estimate based on height and gender, while "healthy weight" is a broader concept that considers body composition, fitness level, medical history, and other individual factors. A person can be healthy at a weight somewhat above or below their calculated IBW. The healthy weight range shown in our calculator (the ideal weight plus or minus 10%) gives a more practical target zone. BMI between 18.5 and 24.9 is another commonly used healthy weight reference.
Can athletes use this calculator?
Athletes can use the calculator as a reference, but should interpret the results with caution. Muscular athletes often weigh more than their calculated ideal weight because muscle is denser than fat. A bodybuilder, football lineman, or competitive weightlifter may exceed their IBW by 10-20 kg or more while maintaining excellent health. For athletes, body fat percentage, waist-to-hip ratio, and sport-specific performance metrics are more meaningful indicators than scale weight alone.
Does this calculator work for all heights?
These formulas were designed for adults 5 feet (152 cm) or taller. For individuals shorter than 5 feet, the formulas use the base weight for 5 feet as the minimum, which may overestimate ideal weight. For very tall individuals (above 6'4" or 193 cm), the linear extrapolation may become less accurate. The formulas are also designed for adults only and should not be used for children or adolescents, who have different growth-dependent body composition patterns.
How accurate are ideal weight calculators compared to a doctor's assessment?
Ideal weight calculators provide a quick, evidence-based starting point, but they cannot replace a physician's comprehensive assessment. Doctors consider your complete medical history, blood work, blood pressure, body composition, lifestyle, family history, and personal goals when recommending a target weight. These formulas also do not account for age, ethnicity, or body fat distribution, all of which influence what constitutes a healthy weight for a specific individual. Use this calculator as an informational tool and discuss the results with your healthcare provider.
