IBW Calculator

May 6, 2026

Setting a target weight is a common starting point for health and fitness plans. The IBW calculator gives you an evidence‑based estimate of your ideal body weight using four widely recognized formulas. Enter your height and gender to see your results instantly.

Interactive IBW Calculator

The calculator above applies the Devine, Robinson, Miller, and Hamwi equations to your height and gender. Each formula yields a slightly different value, so the tool provides a range that reflects the variation among clinical standards. Use the results as a reference point, not a definitive number.

What Is Ideal Body Weight (IBW)?

Ideal body weight is the weight at which a person is statistically expected to have the lowest risk of mortality. It was originally developed for estimating drug dosages and nutritional requirements. Today, clinicians also use IBW to set mechanical ventilation parameters and calculate body surface area.

Unlike body mass index, which classifies your current weight, IBW gives a single target number derived from height and sex. The concept dates back to the mid‑20th century, with multiple formulas proposed over the years.

IBW Formulas Explained

All four formulas use height above a baseline of 5 feet (152.4 cm). Results are given in kilograms.

Devine (1974)

Male: 50 kg + 2.3 kg per inch over 5 feet
Female: 45.5 kg + 2.3 kg per inch over 5 feet Most commonly used in clinical practice, especially for drug dosing.

Robinson (1983)

Male: 52 kg + 1.9 kg per inch over 5 feet
Female: 49 kg + 1.7 kg per inch over 5 feet Developed from updated mortality data; often gives a slightly lower value than Devine for tall individuals.

Miller (1983)

Male: 56.2 kg + 1.41 kg per inch over 5 feet
Female: 53.1 kg + 1.36 kg per inch over 5 feet Based on a different dataset; tends to produce the lowest estimates among the four.

Hamwi (1964)

Male: 48 kg + 2.7 kg per inch over 5 feet
Female: 45.5 kg + 2.2 kg per inch over 5 feet An earlier formula still used in some nutritional assessments.

The calculator automatically converts centimeters to inches if you prefer metric units, then applies each formula and displays the results side by side.

Limitations of IBW

IBW formulas assume a standard body composition for a given height and sex. They do not account for:

Age‑related changes in muscle and bone density
Frame size or body fat distribution
Athletes or individuals with high muscle mass
Pregnant or lactating women
Children and adolescents

Because of these limitations, IBW should be considered one piece of a broader health assessment. Waist circumference, body fat percentage, and blood markers often provide a more complete picture.

IBW vs. BMI: Key Differences

Aspect	IBW	BMI
What it calculates	A target weight goal	Weight status based on current weight
Inputs	Height and gender only	Height and current weight
Clinical use	Drug dosing, ventilation	Screening for underweight/obesity
Personalization	None beyond sex	None beyond weight and height

BMI tells you whether your current weight falls into a healthy range; IBW estimates what that healthy weight might be. Both are screening tools and should not replace professional medical advice.

This tool provides estimates for informational purposes only. Always consult a healthcare professional for personalized weight assessments.

Frequently Asked Questions

Which IBW formula is the most accurate?

No single formula is universally accurate. The Devine formula is the most commonly used in clinical settings, especially for drug dosing. However, it does not account for body composition, age, or muscle mass. The Robinson and Miller formulas were updated later but still provide only rough estimates.

Does ideal body weight change with age?

Standard IBW formulas do not factor in age. They assume a static relationship between height and weight. In reality, healthy weight ranges often shift with age due to changes in muscle mass and bone density. For older adults, BMI or waist‑to‑hip ratio may be more relevant.

Can I use IBW if I am very muscular?

IBW is not suitable for heavily muscled individuals. It is based on population averages and cannot distinguish between fat and muscle. Athletes and bodybuilders often have a weight far above their calculated IBW while maintaining low body fat. Body fat percentage is a better indicator in such cases.

How is IBW different from BMI?

BMI uses actual weight and height to classify weight status, while IBW predicts a goal weight based solely on height and gender. IBW gives a target weight, whereas BMI indicates whether your current weight is underweight, normal, or overweight.

What is the Hamwi formula used for?

The Hamwi formula, developed in 1964, is another method for estimating ideal body weight. It is less common than Devine but still appears in some nutritional assessments. It tends to give lower ideal weights for women and higher for men compared to Devine.

Can children or teenagers use an IBW calculator?

No, IBW formulas are designed for adults and do not account for growth and development. Pediatric weight assessment uses growth charts and percentiles based on age and sex. For individuals under 18, consult a healthcare provider for appropriate weight evaluation.