Ideal Weight Calculator — Find Your Perfect Weight Free
Our free Ideal Weight Calculator uses four scientifically validated formulas — Devine, Robinson, Miller, and Hamwi — to determine your healthy weight range based on height, gender, and body frame size. Rather than relying on a single number, this tool provides a comprehensive view of where your weight should fall for optimal health. No sign-up required — enter your measurements and get instant results.
What Is Ideal Body Weight?
Ideal body weight (IBW) refers to the weight range associated with the lowest risk of health complications for a given height and gender. Originally developed in the 1970s for pharmaceutical dosing — medications are often dosed based on IBW rather than actual weight — these formulas have since been adopted as general health guidelines.
It's crucial to understand that "ideal weight" is not a single magic number. It's a statistical estimation based on population studies that identified weight ranges correlated with the lowest mortality rates and fewest weight-related health problems. Individual factors like muscle mass, bone density, body composition, ethnicity, and genetics all influence what's truly optimal for each person.
Modern health professionals increasingly prefer to look at ideal weight as one data point among many — alongside BMI, body fat percentage, waist circumference, blood markers, and overall fitness level — when assessing a patient's health status.
The Four Major IBW Formulas
Devine Formula (1974)
The most widely used IBW formula in clinical practice, developed by Dr. B.J. Devine. Originally created for calculating drug dosages, it became the de facto standard for ideal weight estimation:
- Men: 50 kg + 2.3 kg × (height in inches − 60)
- Women: 45.5 kg + 2.3 kg × (height in inches − 60)
The Devine formula establishes a base weight at 5 feet (60 inches) and adds 2.3 kg for each additional inch. It tends to give higher estimates for tall individuals.
Robinson Formula (1983)
Developed as a modification of the Devine formula with updated population data:
- Men: 52 kg + 1.9 kg × (height in inches − 60)
- Women: 49 kg + 1.7 kg × (height in inches − 60)
The Robinson formula gives slightly lower values for tall men and slightly higher values for women compared to Devine, reflecting updated understanding of healthy weight distributions.
Miller Formula (1983)
Created by Dr. D.R. Miller as an alternative that better accounts for taller individuals:
- Men: 56.2 kg + 1.41 kg × (height in inches − 60)
- Women: 53.1 kg + 1.36 kg × (height in inches − 60)
The Miller formula has a higher base weight but lower per-inch increment, making it more moderate for very tall individuals and potentially more realistic across a wider height range.
Hamwi Formula (1964)
One of the earliest IBW formulas, developed by Dr. G.J. Hamwi:
- Men: 48 kg + 2.7 kg × (height in inches − 60)
- Women: 45.5 kg + 2.2 kg × (height in inches − 60)
The Hamwi formula tends to give higher estimates for tall men due to its larger per-inch increment. It also includes frame size adjustments: add 10% for large frames and subtract 10% for small frames.
Factors Affecting Ideal Weight
Height
Height is the primary determinant in all IBW formulas. Taller individuals naturally require more bone, muscle, and tissue mass. The relationship isn't perfectly linear — very short and very tall individuals may find formula estimates less accurate than those near average height.
Gender
Biological differences between males and females significantly affect ideal weight. Men typically have greater muscle mass (averaging 40% vs 30% body composition), higher bone density, broader shoulders, and different fat distribution patterns. These differences are reflected in separate formula calculations for each gender.
Body Frame Size
Skeletal frame size — determined by bone structure and width — accounts for natural variation. A person with a large frame has thicker bones and broader structure, naturally weighing more than a small-framed person of identical height. Frame size can be estimated by measuring wrist circumference or elbow breadth.
Frame size classifications typically adjust ideal weight by ±10%: small frames should aim for the lower end of the range, while large frames are healthy at the upper end.
Age
While traditional formulas don't account for age, modern research shows age matters. Metabolism slows with age, body composition shifts (more fat, less muscle), and bone density decreases. Some studies suggest slightly higher BMI values (25-27) may be protective for adults over 65, potentially making higher weights more appropriate for older adults.
Muscle Mass & Body Composition
IBW formulas assume average body composition. Athletes, bodybuilders, and physically active individuals may have significantly more muscle mass, making them healthier at weights above the calculated ideal. Body composition analysis (DEXA scan, bioelectrical impedance) provides more accurate assessment for these populations.
Ideal Weight Table by Height
Reference table showing ideal weight ranges using averaged formula results:
| Height | Men (kg) | Men (lbs) | Women (kg) | Women (lbs) |
|---|---|---|---|---|
| 5'0" (152 cm) | 50–54 | 110–119 | 45–49 | 100–108 |
| 5'2" (157 cm) | 55–59 | 121–130 | 49–53 | 108–117 |
| 5'4" (163 cm) | 59–64 | 130–141 | 53–57 | 117–126 |
| 5'6" (168 cm) | 64–69 | 141–152 | 57–62 | 126–137 |
| 5'8" (173 cm) | 69–74 | 152–163 | 62–66 | 137–146 |
| 5'10" (178 cm) | 74–79 | 163–174 | 66–71 | 146–157 |
| 6'0" (183 cm) | 79–84 | 174–185 | 71–76 | 157–168 |
| 6'2" (188 cm) | 84–89 | 185–196 | 76–81 | 168–179 |
| 6'4" (193 cm) | 89–94 | 196–207 | 81–86 | 179–190 |
*Values represent averaged ranges from Devine, Robinson, Miller, and Hamwi formulas for medium frame size.
Ideal Weight vs BMI
While both IBW and BMI assess healthy weight, they approach the question differently. BMI (Body Mass Index) calculates weight ÷ height² and categorizes you into ranges: underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30). IBW formulas give you a specific target weight for your height and gender.
For most people, ideal body weight corresponds to a BMI of approximately 21–23. The two metrics generally agree — if your weight is at the IBW calculated value, your BMI will typically be in the healthy range. However, neither accounts for body composition, so both have limitations for muscular individuals, the elderly, and certain ethnic groups.
Using both metrics together provides a more complete picture: IBW gives you a target, while BMI tells you which health risk category you fall into at your current weight.
Why One Formula Isn't Enough
Each IBW formula was developed using different populations and methodologies, which is why they produce different results. The Devine formula may overestimate for tall women, while the Hamwi formula may overestimate for tall men. By presenting all four formulas together, our calculator gives you a realistic range rather than a single potentially misleading number.
The range between the lowest and highest formula results typically spans 3-7 kg (7-15 lbs). This range itself is informative — it shows the inherent uncertainty in defining "ideal" and reinforces that health exists on a spectrum, not at a precise point. If all four formulas agree closely, you can be more confident in the estimate; if they diverge significantly, individual factors likely matter more.
Frequently Asked Questions
What is ideal body weight?
Ideal body weight (IBW) is a weight range associated with optimal health outcomes based on your height, gender, and body frame. It's not a single number but a range derived from medical research, originally developed for pharmaceutical dosing calculations and later adopted as general health guidelines for the population.
Which ideal weight formula is most accurate?
No single formula is universally most accurate. The Devine formula is most widely used in clinical settings for drug dosing. The Robinson formula tends to give slightly lower estimates. The Miller formula accounts better for taller individuals. Using multiple formulas and considering the range gives the most realistic picture of your ideal weight.
How does body frame size affect ideal weight?
Body frame size (small, medium, large) can adjust your ideal weight by approximately ±10%. A large-framed person naturally carries more bone and muscle mass, so their healthy weight is higher than a small-framed person of the same height. Frame size is typically determined by wrist circumference or elbow breadth measurement.
Is ideal weight different for men and women?
Yes, ideal weight formulas account for gender differences in body composition. Men typically have higher ideal weights than women of the same height due to greater average muscle mass, bone density, and different body composition patterns. All major IBW formulas have separate calculations for men and women.
What is the difference between ideal weight and BMI?
Ideal weight formulas give you a specific weight target based on height and gender. BMI (Body Mass Index) is a ratio of weight to height squared that categorizes you as underweight, normal, overweight, or obese. For most people, ideal body weight corresponds to a BMI of approximately 21–23.
Can athletes have an ideal weight above the calculated range?
Yes, athletes and highly muscular individuals often weigh more than IBW formulas suggest while being perfectly healthy. These formulas were designed for average body compositions. Muscle weighs more than fat, so a muscular person's healthy weight may exceed the calculated ideal. Body composition analysis is more appropriate for athletes.
Does age affect ideal body weight?
Traditional IBW formulas don't account for age, but research suggests that slightly higher weights may be acceptable or even protective for older adults (over 65). Metabolism changes, bone density decreases, and body composition shifts with age. Some health professionals recommend higher target weights for elderly patients.
Should I aim for my exact ideal weight?
No, you should aim for a healthy range rather than an exact number. Most health professionals consider a range of ±10% from the calculated ideal weight to be healthy. Factors like muscle mass, bone structure, body composition, and overall fitness matter more than hitting a precise number on the scale.