Ideal Weight Calculator

The Ideal Weight Calculator estimates your ideal body weight using four clinically-recognized formulas developed by physicians and researchers. By comparing results from the Devine, Robinson, Miller, and Hamwi formulas, you get a realistic weight range rather than a single number — because healthy weight varies based on body frame, muscle mass, and individual factors.

The Four Ideal Weight Formulas

All four formulas share the same structure: a base weight for 5 feet (60 inches) of height, plus an increment for each additional inch. They differ in their base values and per-inch increments, reflecting different study populations and assumptions.

Devine Formula (1974)

Developed by Dr. B.J. Devine, this is the most widely used formula in clinical medicine. It was originally created for calculating medication dosages based on body weight but became the de facto standard for ideal body weight (IBW) estimation.

Robinson Formula (1983)

Dr. J.D. Robinson refined the Devine formula using updated data from Metropolitan Life Insurance tables. It tends to produce slightly higher estimates for men and slightly lower for women compared to Devine.

Miller Formula (1983)

Dr. D.R. Miller developed this formula in the same year as Robinson. It typically produces the highest ideal weight values of the four formulas, reflecting a more generous view of healthy weight that accounts for naturally heavier builds.

Hamwi Formula (1964)

The earliest of the four, developed by Dr. G.J. Hamwi for use in nutrition assessment. It is commonly used by dietitians and has the steepest per-inch increment for men, making it produce higher values for taller individuals.

Body Frame Size

Body frame size significantly affects your ideal weight. People with larger bone structures naturally weigh more, even at the same height and body fat percentage. You can estimate your frame size by measuring your wrist circumference:

This calculator adjusts the ideal weight by −10% for small frames and +10% for large frames, following the standard clinical practice.

How to Use This Calculator

1. Select your gender: Choose male or female. The formulas use different base weights and increments for each gender.
2. Enter your height: Use either feet & inches or centimeters. Toggle between units using the switch buttons.
3. Choose your frame size: Select small, medium, or large based on your wrist measurement (see table above).
4. Optionally enter your age: While not used in the formulas directly, age provides context for personalized insights.
5. Click Calculate: Review results from all four formulas, the healthy BMI range, the visual comparison chart, and personalized insights.

Understanding Your Results

• Average Ideal Weight: The mean of all four formula results — a good single reference number.
• Formula Range: The spread between the lowest and highest formula results. A narrow range means strong agreement; a wide range suggests more uncertainty.
• Healthy BMI Range: The weight range corresponding to a BMI of 18.5–24.9 for your height. This is an independent check against the formula results.
• Formula Comparison Chart: Visual bar chart showing each formula's result for easy comparison.
• Smart Insights: Personalized observations based on your inputs, including frame size effects and age considerations.

Limitations of Ideal Weight Formulas

• Formulas do not account for body composition — a muscular person may be healthy well above the calculated ideal weight
• All formulas were developed using primarily Caucasian populations and may be less accurate for other ethnic groups
• They are designed for adults only — children and adolescents should use age-specific growth charts
• Results are estimates, not health prescriptions — consult a healthcare provider for personalized guidance
• Factors like muscle mass, bone density, age, and genetics all influence what a healthy weight looks like for you

Frequently Asked Questions

What is the most accurate ideal weight formula?

No single formula is universally the most accurate. The Devine formula is the most widely used in clinical settings, while the Miller formula tends to allow for higher weights. Using multiple formulas gives a range that better reflects individual variation. The best approach is to consider the average of all four formulas along with the healthy BMI range.

How does body frame size affect ideal weight?

People with larger bone structures naturally weigh more. A small frame adjustment reduces ideal weight by about 10%, while a large frame adds about 10%. You can estimate your frame size by measuring your wrist circumference — smaller wrists generally indicate a smaller frame.

Are ideal weight formulas accurate for athletes?

Ideal weight formulas may underestimate healthy weight for muscular athletes, as they do not account for body composition. Athletes with high muscle mass can be healthy at weights above the formula estimates. Body fat percentage is a better metric for athletic individuals.

What is a healthy BMI range?

A healthy BMI is generally 18.5 to 24.9 for adults. This translates to different weight ranges depending on height. BMI does not distinguish between muscle and fat, so it should be used alongside other health indicators.

Should I aim for the exact ideal weight number?

No. Ideal weight formulas provide estimates, not precise targets. A range of plus or minus 10% around the calculated ideal weight is generally considered healthy. Focus on overall health, energy levels, and body composition rather than hitting an exact number on the scale.

Additional Resources

• Ideal Body Weight - Wikipedia
• Body Mass Index (BMI) - Wikipedia