Ideal Weight Calculator — Find Your Target Weight

What Is an Ideal Weight Calculator?

An ideal weight calculator estimates a reference body weight from your height and sex. Instead of presenting one number as a universal target, this calculator compares four commonly used ideal body weight (IBW) formulas: Devine, Robinson, Miller, and Hamwi.

It also shows a BMI-based healthy weight range. That gives you two different ways to interpret your result: traditional IBW equations provide reference estimates, while BMI provides a range of body weights corresponding to the adult BMI range of 18.5–24.9.

These approaches are not interchangeable and neither one should be treated as a precise definition of your personally ideal body weight.

How Is Ideal Body Weight Calculated?

The four formulas used here estimate body weight from height and sex. They use a base weight at 5 feet and then add a fixed amount for each inch above 5 feet. The equations produce slightly different estimates because they were developed using different historical datasets and methods.

Devine Formula

The Devine formula was published in 1974 and became widely used for estimating ideal body weight in clinical and drug-dosing contexts.

• Men: 50.0 kg + 2.3 kg × each inch over 5 ft
• Women: 45.5 kg + 2.3 kg × each inch over 5 ft

Hamwi Formula

The Hamwi formula dates to 1964 and is another traditional reference equation for estimating desirable body weight.

• Men: 48.0 kg + 2.7 kg × each inch over 5 ft
• Women: 45.5 kg + 2.2 kg × each inch over 5 ft

Robinson Formula

The Robinson formula was published in 1983 using height-weight data to derive sex-specific ideal body weight equations.

• Men: 52.0 kg + 1.9 kg × each inch over 5 ft
• Women: 49.0 kg + 1.7 kg × each inch over 5 ft

Miller Formula

The Miller formula is another 1983 reference equation and uses different coefficients from the Devine, Hamwi, and Robinson methods.

• Men: 56.2 kg + 1.41 kg × each inch over 5 ft
• Women: 53.1 kg + 1.36 kg × each inch over 5 ft

Which Ideal Body Weight Formula Is Most Accurate?

There is no universally accepted “most accurate” IBW formula. Devine, Hamwi, Robinson, and Miller can produce different results for the same height because they were developed from different historical data and approaches.

Research comparing IBW equations has found that the formulas do not always align with the same BMI value across different heights. For that reason, comparing multiple equations and looking at a healthy BMI-based range can provide more context than choosing one formula as the definitive answer.

The four-formula comparison above is therefore a reference tool, not a ranking of which equation is universally correct.

What Should I Weigh for My Height and Age?

For the adult IBW formulas on this page, age is not part of the calculation. Devine, Hamwi, Robinson, and Miller use height and sex rather than age.

That means a search such as “ideal weight by age” should not be interpreted as though every adult age has a separate IBW number. Age can matter when assessing health, body composition, or other clinical factors, but it is not an input to these four classic IBW equations.

For adults, you can use the BMI Calculator alongside this tool to see how your weight relates to height using a BMI-based range.

Ideal Weight vs Healthy Weight

“Ideal weight” and “healthy weight” are not interchangeable terms. Traditional IBW formulas return a mathematical reference estimate, while a healthy-weight assessment can involve BMI, body composition, health history, physical activity, and other individual factors.

A person can be above a traditional IBW estimate without having excess body fat, particularly when they have substantial muscle mass. Conversely, being within an IBW estimate does not automatically mean that a person has an optimal body composition or overall health.

Does Ideal Weight Include Muscle Mass?

No. Traditional IBW equations do not directly measure muscle mass, fat mass, skeletal size, or other components of body composition. They primarily use height and sex.

This limitation matters for bodybuilders, strength athletes, and muscular lifters. Someone who carries substantially more lean mass than the population represented by a traditional height-weight equation may weigh more than the calculated IBW while still having a healthy body composition.

If you are a lifter, use the result as a reference rather than as a mandatory target. Our Body Fat Calculator can provide additional body-composition context.

You can also use the Lean Body Mass Calculator to estimate fat-free mass, or the FFMI Calculator to put lean mass into a height-adjusted context.

Ideal Weight for Bodybuilders and Lifters

If you lift weights regularly, an IBW calculator can produce a result that feels surprisingly low. That does not necessarily mean that you should lose weight to reach the calculated number.

Traditional IBW equations were not designed to identify the ideal scale weight for a muscular athlete. They also do not account for how much of your body weight comes from muscle versus fat.

For a fitness-focused assessment, consider your body-fat percentage, lean body mass, performance, health markers, and personal goals alongside scale weight.

If your goal is to move toward a specific body weight, the Calorie Deficit Calculator can help estimate a calorie target and projected timeline. If your goal is nutrition planning rather than weight loss, the Macro Calculator can help you set starting protein, carbohydrate, and fat targets.

What Is the Healthy BMI Weight Range?

For adults, a BMI of 18.5 through 24.9 is commonly used as the “healthy weight” BMI category. Converting those BMI values back into body weight creates a height-specific weight range.

The calculation is: Weight = BMI × Height² when height is expressed in meters and weight in kilograms.

Unlike the traditional IBW formulas, a BMI range gives you more than one target weight. However, BMI also has an important limitation: it cannot distinguish muscle mass from fat mass.

For that reason, muscular athletes should not interpret either BMI or traditional IBW as a complete body-composition assessment.

Why Do Different Ideal Weight Calculators Give Different Results?

Different calculators may use different equations. Some use Devine, some use Robinson or Miller, and others use Hamwi or BMI-based calculations.

Even when two calculators use the same formula, differences can appear because of rounding, height conversion, unit conversion, or how heights below and above 5 feet are handled.

RepMaths shows the four reference equations separately so you can see the calculation rather than hiding those differences behind one unexplained number.

Sources & Methodology

RepMaths uses the commonly published Devine, Hamwi, Robinson, and Miller ideal body weight equations and calculates a separate BMI weight range using BMI values of 18.5 and 24.9.

• Robinson et al. (1983), ideal body weight equations derived from height-weight data.
• Pai & Paloucek (2000), historical review of the origin and use of ideal body weight equations.
• Peterson et al. (2016), research comparing IBW equations with BMI and proposing a universal height/BMI-based equation.

These equations are presented for educational and fitness-planning purposes. They are not a diagnosis and should not be used as a substitute for individualized medical advice.

Frequently Asked Questions