What Is Ideal Body Weight — and Should You Trust Any Single Formula?
Ideal Body Weight (IBW) is a clinically-derived estimate of the weight at which a person of a given height is statistically associated with optimal health outcomes. The term was popularised in the 1960s by actuarial studies from life insurance companies who noticed that certain weight ranges correlated with lower mortality risk. Since then, six major IBW formulas have been developed — all producing slightly different numbers, all with their own limitations, and none of which should be treated as a precise personal target without medical context.
This calculator computes your ideal weight across all six validated formulas simultaneously so you can see the range rather than a single potentially misleading number. The range between the lowest and highest formula for any given height can easily be 5–8 kg — a reminder that IBW is a screening tool, not a prescription.
What Each Formula Was Originally Designed For
The Devine formula (1974) was not designed as a health metric — it was originally used to calculate drug dosages in clinical pharmacology. The Robinson formula (1983) was developed from a broader population sample and is generally more accurate across the adult height range. The Hamwi method (1964), Miller formula (1983), Broca Index (Height cm − 100/105), and BMI-based method each represent different approaches to the same relationship between height and healthy weight.
Why IBW Cannot Tell the Whole Story
Every IBW formula shares the same fundamental limitation: they use only height and sex, ignoring body composition entirely. A 175 cm male bodybuilder at 85 kg with 8% body fat will be classified "overweight" by every formula. A 175 cm male at 72 kg with 25% body fat will be "ideal." The bodybuilder is metabolically far healthier. IBW is most useful as a rough screening tool, not a definitive verdict. Also see our BMI Calculator and BMR Calculator.
Calculate Your Ideal Weight
Get your ideal body weight across 6 scientific formulas plus your BMI healthy range
All 6 Formula Results
Your Weight Journey
What Is Ideal Body Weight?
Understanding IBW, healthy weight ranges and what the science actually says
Ideal Body Weight (IBW) is the weight range associated with the lowest risk of weight-related health problems for a person of a given height. It was originally developed for medical applications — primarily to calculate accurate drug dosages — but is now widely used for health assessment, fitness goals and clinical nutrition.
The concept of ideal weight is inherently imprecise, because body weight is just one dimension of health. Two people of identical height and weight can have very different body compositions — one might have 20% body fat and the other 35%. The person with lower body fat is almost certainly healthier despite having the same weight. This is why body composition matters more than weight alone.
The most reliable measure for most people remains the BMI healthy range (18.5–24.9), which corresponds to the weights that produce a BMI within this range for a given height. This approach avoids the assumptions built into fixed-formula methods and has the largest body of epidemiological evidence behind it.
The 6 Ideal Weight Formulas
Every formula explained — how it works, who developed it and when
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1
Robinson Formula (1983) — Most Recommended
Published by Robinson et al. in 1983, this is widely considered the most validated formula for general use. It's the most commonly cited in clinical research and nutritional guidelines.
Male: 52 kg + 1.9 kg × (height_in − 60)
Female: 49 kg + 1.7 kg × (height_in − 60) -
2
Miller Formula (1983)
Also published in 1983 by Miller et al., this formula tends to produce slightly lower ideal weights than Robinson. It is commonly used in pharmaceutical dosing calculations alongside Robinson.
Male: 56.2 kg + 1.41 kg × (height_in − 60)
Female: 53.1 kg + 1.36 kg × (height_in − 60) -
3
Devine Formula (1974)
Originally developed by B.J. Devine in 1974 for creatinine clearance calculations in renal medicine. Despite being designed for pharmaceutical use, it became widely adopted as an IBW reference.
Male: 50 kg + 2.3 kg × (height_in − 60)
Female: 45.5 kg + 2.3 kg × (height_in − 60) -
4
Hamwi Formula (1964) — Classic Standard
Developed by G.J. Hamwi in 1964, this was one of the earliest widely adopted IBW formulas. It uses a base weight of 106 lb (men) or 100 lb (women) for 5 feet, adding 6 lb or 5 lb per inch above that.
Male: 48.1 kg + 2.72 kg × (height_in − 60)
Female: 45.4 kg + 2.27 kg × (height_in − 60) -
5
Broca Index (1871) — Historical
Proposed by French anthropologist Pierre Paul Broca in 1871 — one of the first attempts to quantify ideal weight from height. Simple but less precise than modern formulas. Still used as a quick reference.
Male: height_cm − 100
Female: (height_cm − 100) × 0.9 -
6
BMI-Based Healthy Range
Rather than a single ideal weight, this method calculates the weight range corresponding to a healthy BMI (18.5–24.9). It's the most evidence-based approach and accounts for the full range of healthy weights at any height.
Min weight = 18.5 × height² (m²)
Max weight = 24.9 × height² (m²)
Ideal Weight Chart by Height
Average ideal weight and BMI healthy range for common heights
| Height | IBW Avg | Healthy Range (BMI) |
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| Height | IBW Avg | Healthy Range (BMI) |
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Interesting Facts About Body Weight & Health
Science-backed insights about weight, health and body composition
Muscle Weighs More Than Fat by Volume
Muscle tissue is approximately 18% denser than fat. This means a very muscular person will weigh more at the same waist size as someone with more fat — which is why weight alone is a poor indicator of body composition or health.
Where Fat Is Stored Matters Most
Visceral fat — stored around the abdominal organs — is far more metabolically dangerous than subcutaneous fat stored under the skin. People with "normal" BMI but excess belly fat (TOFI: Thin Outside, Fat Inside) carry significant health risks.
Even Small Weight Losses Have Big Health Benefits
Losing just 5–10% of body weight in overweight individuals significantly reduces blood pressure, blood sugar, triglycerides and LDL cholesterol. You don't need to reach your "ideal" weight to see major health improvements.
Genetics Accounts for ~40–70% of Weight Variation
Twin studies show that genetics explains 40–70% of the variation in body weight between individuals. However, genetics sets a tendency, not a destiny — lifestyle factors profoundly influence whether genetic predispositions are expressed.
Sleep Affects Weight More Than Diet for Many People
Chronic sleep deprivation (under 7 hours) is associated with a 55% increased risk of obesity. Poor sleep raises ghrelin, lowers leptin, increases cortisol and impairs decision-making — creating a perfect storm for overeating and weight gain.
Strength Training Outperforms Cardio for Long-Term Weight
While cardio burns more calories during a session, strength training increases resting metabolic rate by building lean muscle mass — meaning you burn more calories 24/7. Muscle tissue burns ~3× more calories at rest than fat.
The Gut Microbiome Influences Weight
Research shows that the composition of gut bacteria affects how efficiently calories are extracted from food, fat storage patterns and even food cravings. Identical twins with different microbiomes can have significantly different weights on the same diet.
Weight Set Point Theory
The body actively defends a "set point" weight range through hormonal mechanisms. When you lose weight, metabolism slows and hunger hormones surge to push you back toward baseline — which is why maintaining weight loss requires ongoing lifestyle changes.
Frequently Asked Questions
Common questions about ideal weight, BMI and healthy weight ranges
The Muscular Athlete
175 cm male, 84 kg. IBW says ideal is 68–72 kg — he is 12 kg "over." Body fat: 10%. Lean muscle: 75 kg. Cardiovascular markers: elite. IBW cannot distinguish muscle from fat. IBW wrong — body composition matters far more.
Body comp overrides IBWThe Older Adult (Age 72)
168 cm female, 65 kg. IBW says ideal is 56–60 kg. Research shows older adults (65+) have lower mortality at slightly higher BMI (23–26). Being at "ideal" weight at 72 may mean insufficient muscle mass and fragility fracture risk. IBW formulas were not validated for the elderly.
Older adults: slightly higher weight saferThe South Asian at Normal IBW
165 cm male, 68 kg. IBW: ideal. But South Asian populations have higher metabolic risk at "normal" BMI levels. Many Asian health authorities use BMI 23 as the overweight threshold. His target weight may need to be lower. IBW formulas are not ethnicity-adjusted.
Asian-adjusted thresholds applyPregnancy (IBW is irrelevant)
A 163 cm woman at 72 kg (28 weeks pregnant) will be above her IBW of 55–59 kg. The extra weight is medically necessary. Using IBW during pregnancy to set a weight target is actively harmful. Use pre-pregnancy BMI and gestational weight gain guidelines instead.
Never use IBW during pregnancy