Ideal Weight Calculator
Calculate your ideal body weight using multiple scientifically-developed formulas based on your height and gender.
Ideal Weight Formulas
Devine Formula
Robinson Formula
What is Ideal Body Weight?
Ideal body weight (IBW) is an estimated weight considered healthiest for a person based on their height and sometimes gender. Unlike a single 'perfect' number, ideal weight is better understood as a healthy weight range that accounts for individual variation in body composition, bone structure, and muscle mass.
These formulas were originally developed for medical purposes, particularly for calculating drug dosages, mechanical ventilation settings, and nutritional requirements. While they provide useful reference points, they don't account for factors like muscle mass, body fat percentage, or overall fitness level.
Multiple Formulas
Compare results from four well-established scientific formulas for a comprehensive view.
Gender-Specific
Calculations account for biological differences in body composition between men and women.
Height-Based
All formulas use height as the primary determinant of ideal weight.
Healthy Range
Also provides BMI-based healthy weight range for additional context.
Understanding the Formulas
Each formula has its own history and methodology. Here's what you need to know about each:
Devine Formula (1974)
The most widely used formula in clinical medicine. Developed by Dr. B.J. Devine for drug dosing calculations. It was based on estimates from insurance data, not direct measurements. Men: 50 kg + 2.3 kg per inch over 5 feet. Women: 45.5 kg + 2.3 kg per inch over 5 feet.
Robinson Formula (1983)
A modification of the Devine formula that tends to give slightly higher weights for men and lower for women. Often considered more accurate for average body frames. Men: 52 kg + 1.9 kg per inch over 5 feet. Women: 49 kg + 1.7 kg per inch over 5 feet.
Miller Formula (1983)
Tends to produce higher ideal weights than other formulas, which may be more realistic for modern populations. Men: 56.2 kg + 1.41 kg per inch over 5 feet. Women: 53.1 kg + 1.36 kg per inch over 5 feet.
Hamwi Formula (1964)
The oldest of the common formulas, developed by Dr. G.J. Hamwi. Still widely used in nutrition and dietetics. Men: 48 kg + 2.7 kg per inch over 5 feet. Women: 45.5 kg + 2.2 kg per inch over 5 feet.
How Frame Size Affects Ideal Weight
Your frame size (bone structure) affects what weight is healthy for you. People with larger frames naturally weigh more due to denser, larger bones, while those with smaller frames weigh less. Here's how to estimate your frame size:
Wrist measurement method: Wrap your thumb and middle finger around your wrist at the narrowest point. If they overlap, you have a small frame. If they just touch, you're medium-framed. If they don't touch, you have a large frame.
| Frame Size | Weight Adjustment | Characteristics |
|---|---|---|
| Small Frame | -10% | Narrow shoulders, small wrists and ankles, often ectomorphic body type |
| Medium Frame | Base weight | Average bone structure, most formulas calibrated for this frame |
| Large Frame | +10% | Broad shoulders, larger wrists and ankles, often mesomorphic body type |
Ideal Weight vs. Healthy Weight
It's important to understand the difference between 'ideal weight' calculated by formulas and what's truly healthy for you individually:
Muscle Mass Matters
Athletic individuals with significant muscle mass may weigh more than their 'ideal' weight yet be perfectly healthy. Muscle weighs more than fat, so these formulas may underestimate healthy weight for fit people.
Health Over Numbers
Your overall health—blood pressure, cholesterol, blood sugar, fitness level—matters more than hitting a specific number. Someone slightly above 'ideal' with good health markers is better off than someone at 'ideal' weight with poor metrics.
Genetic Variation
Genetics play a significant role in where your body naturally settles. Some people maintain excellent health at weights above or below formula predictions due to their unique physiology.
Formula Limitations
These formulas were developed decades ago, often based on insurance data or limited populations. They don't account for ethnicity, age, or modern understanding of body composition.
Using Ideal Weight for Health Goals
While not perfect, ideal weight calculations can serve as useful starting points for health planning:
Set Realistic Goals
If you're significantly above all formula estimates, working toward the average can be a reasonable initial goal. Don't expect to reach the lowest formula result—aim for the range.
Gradual Progress
Healthy weight loss is 0.5-2 pounds per week. Calculate how your current weight compares to ideal, then set a sustainable timeline. Quick fixes rarely work long-term.
Combine with Fitness
Weight alone doesn't determine health. Combine weight goals with strength training and cardiovascular exercise for optimal body composition and health outcomes.
Reassess Periodically
As you lose weight or gain muscle, your 'ideal' target may shift. Someone who builds significant muscle might have a new healthy target above the original formula results.
Limitations of Ideal Weight Formulas
Understanding what these formulas cannot tell you is just as important as the numbers they provide:
No Body Composition
Formulas don't distinguish between muscle and fat. Two people at the same height and 'ideal' weight could have vastly different body fat percentages.
Age Not Considered
Ideal weight formulas don't account for age, though body composition naturally changes throughout life. What's ideal at 25 may differ from what's healthy at 65.
Ethnicity Variations
These formulas were largely developed using data from Western populations. Research shows ideal BMI and weight ranges may differ across ethnic groups.
Historical Bias
Most formulas date from the 1960s-1980s and were based on limited data, sometimes from insurance tables rather than health research.
Better Measures of Health
While ideal weight provides a reference point, consider these additional metrics for a complete picture of your health:
Waist Circumference
A better predictor of health risks than weight alone. Men should aim for under 40 inches, women under 35 inches. Excess abdominal fat increases disease risk.
Body Fat Percentage
Measures actual fat vs. lean mass. Healthy ranges are 10-20% for men and 18-28% for women. More informative than scale weight alone.
Waist-to-Hip Ratio
Divide waist measurement by hip measurement. Below 0.9 for men and 0.85 for women indicates lower cardiovascular risk.
Health Markers
Blood pressure, cholesterol, blood sugar, and resting heart rate are often better indicators of health than body weight.
Frequently Asked Questions
Which ideal weight formula is most accurate?
No single formula is definitively most accurate. The Devine formula is most commonly used in medicine, but it tends to underestimate for tall people and overestimate for short people. The Robinson formula is often considered more balanced. Using the average of all formulas usually provides the best estimate.
Why do the formulas give different results?
Each formula was developed using different data sets, time periods, and methodologies. Devine used insurance data, Robinson modified Devine's work, Miller used more recent population data, and Hamwi was based on clinical observations. The variation actually provides useful context—your healthy range likely falls somewhere within all results.
Should I trust ideal weight formulas?
Use them as rough guidelines, not absolute targets. They're most useful for identifying if you're significantly outside healthy ranges. For precise health assessment, consider body fat percentage, waist circumference, and consultation with healthcare providers.
I'm athletic and weigh more than my 'ideal weight.' Is that bad?
Not at all. These formulas don't account for muscle mass. Athletes and regular exercisers often exceed ideal weight calculations while being very healthy. If you have significant muscle mass, your actual healthy weight is likely higher than these formulas suggest.
What if I'm short or very tall?
These formulas are least accurate at height extremes. For people under 5 feet or over 6'2", the formulas may significantly under- or over-estimate ideal weight. Consider using BMI-based healthy weight ranges instead, which scale more proportionally with height.
How do I determine my frame size?
The simplest method is the wrist test: wrap your thumb and middle finger around your wrist at the narrowest point. If they overlap, you have a small frame. If they just touch, medium frame. If they don't meet, large frame. For more precision, measure wrist circumference and compare to height-based charts.
Why don't these formulas consider age?
These formulas were designed for simplicity in clinical settings. While body composition changes with age, the basic height-weight relationship the formulas model doesn't change dramatically. However, some experts suggest that slightly higher weights may be protective in older adults.
Is there one 'perfect' weight I should aim for?
No. Health exists across a range of weights. Think of 'ideal weight' as the center of a healthy zone, not a single magic number. Being within 10-15% of formula estimates while maintaining good health markers, fitness, and energy levels is what matters.
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