Is There Such a Thing as an Ideal Weight?
Not in the way the phrase suggests. There is no single weight that is correct for a person of a given height. What exists is a set of clinical formulas, developed for specific medical purposes, and a healthy range derived from population health outcomes. The formulas produce a single number because a single number was needed for the task they were built for — not because a single number is biologically meaningful.
Every formula on this page depends on height and sex alone. None accounts for frame size, muscle mass, body composition, age or ethnicity. A muscular athlete and a sedentary person of identical height receive identical "ideal" weights, which should tell you how to interpret the output.
Why These Formulas Exist
Ideal body weight formulas were not created for dieters. They were created because certain medical decisions require a weight estimate that is independent of how much fat a patient is carrying:
- Drug dosing — many medications distribute through lean tissue rather than fat, so dosing on actual weight would overdose an obese patient. Aminoglycoside antibiotics, chemotherapy agents and anaesthetics are commonly dosed on ideal or adjusted body weight.
- Mechanical ventilation — lung volume scales with height, not weight. Tidal volumes are set at 6–8 mL per kilogram of predicted body weight, and using actual weight in an obese patient causes lung injury.
- Nutritional assessment — estimating energy and protein requirements in hospital.
- Renal function — creatinine clearance equations use ideal or adjusted weight.
The Four Formulas
All four take the same shape: a base weight at five feet, plus an increment per inch above that.
Robinson (1983) — Men: 52 kg + 1.9 kg per inch over 5 ft | Women: 49 kg + 1.7 kg per inch
Miller (1983) — Men: 56.2 kg + 1.41 kg per inch | Women: 53.1 kg + 1.36 kg per inch
Devine (1974) — Men: 50.0 kg + 2.3 kg per inch | Women: 45.5 kg + 2.3 kg per inch
Hamwi (1964) — Men: 48.0 kg + 2.7 kg per inch | Women: 45.5 kg + 2.2 kg per inch
The Devine formula is the one used most widely in clinical practice, largely by historical accident: Devine proposed it for dosing without supporting data, and it became standard because it was simple and everyone else adopted it. Robinson and Miller are later modifications fitted to actuarial data. Hamwi was designed for estimating dietary needs in diabetic patients and gives the widest spread across heights.
Note what happens below five feet: because the formulas subtract per inch, they produce implausibly low values for short adults, and negative values at extreme heights. This is a known limitation and one reason the BMI range is preferable for general use.
Ideal Weight by Height
| Height | Men (Robinson) | Women (Robinson) | Healthy BMI range |
|---|---|---|---|
| 4' 10" | 106 lb | 101 lb | 89 – 120 lb |
| 4' 11" | 110 lb | 104 lb | 92 – 124 lb |
| 5' 0" | 115 lb | 108 lb | 95 – 128 lb |
| 5' 1" | 119 lb | 112 lb | 98 – 132 lb |
| 5' 2" | 123 lb | 116 lb | 101 – 137 lb |
| 5' 3" | 127 lb | 119 lb | 104 – 141 lb |
| 5' 4" | 131 lb | 123 lb | 108 – 146 lb |
| 5' 5" | 136 lb | 127 lb | 111 – 150 lb |
| 5' 6" | 140 lb | 131 lb | 115 – 155 lb |
| 5' 7" | 144 lb | 134 lb | 118 – 160 lb |
| 5' 8" | 148 lb | 138 lb | 122 – 164 lb |
| 5' 9" | 152 lb | 142 lb | 125 – 169 lb |
| 5' 10" | 157 lb | 146 lb | 129 – 174 lb |
| 5' 11" | 161 lb | 149 lb | 133 – 179 lb |
| 6' 0" | 165 lb | 153 lb | 136 – 184 lb |
| 6' 1" | 169 lb | 157 lb | 140 – 189 lb |
| 6' 2" | 173 lb | 160 lb | 144 – 195 lb |
| 6' 3" | 177 lb | 164 lb | 148 – 200 lb |
| 6' 4" | 182 lb | 168 lb | 152 – 205 lb |
| 6' 5" | 186 lb | 172 lb | 156 – 211 lb |
| 6' 6" | 190 lb | 175 lb | 160 – 216 lb |
The BMI column is consistently wider than the single-value formulas, and it is the range that health authorities actually use to define healthy weight. A person can sit anywhere within it and be entirely healthy.
Frame Size
None of the formulas adjusts for skeletal frame, though frame accounts for a real difference of several kilograms at the same height. A rough estimate uses wrist circumference relative to height:
| Frame | Women (height ÷ wrist) | Men (height ÷ wrist) | Adjustment |
|---|---|---|---|
| Small | over 11.0 | over 10.4 | Subtract about 10% |
| Medium | 10.1 – 11.0 | 9.6 – 10.4 | No adjustment |
| Large | under 10.1 | under 9.6 | Add about 10% |
What Actually Determines a Healthy Weight
For an individual, the more informative questions are not about the number on the scale:
- Body composition — the ratio of fat to lean mass matters far more than total weight.
- Waist circumference — above 40 inches in men or 35 in women indicates elevated cardiometabolic risk at any weight.
- Metabolic markers — blood pressure, fasting glucose, HbA1c and lipid profile.
- Fitness — cardiorespiratory fitness independently predicts mortality, and a fit person at a higher weight often has better outcomes than an unfit person at a lower one.
- Weight stability — repeated large fluctuations are associated with worse outcomes than a stable higher weight.
Frequently Asked Questions
Why do the four formulas disagree?
They were fitted to different populations for different purposes across two decades. At 5'10" they span roughly 8 kilograms, which is an honest indication of how much precision the concept really has.
Which number should I use?
For a personal target, use the healthy BMI range rather than any single formula. The formulas are clinical instruments; the range reflects the actual evidence on health outcomes.
Do these apply to children?
No. Children's healthy weight is assessed against age- and sex-specific growth percentiles, not adult formulas.
Do they apply to athletes?
Poorly. A muscular athlete will exceed every formula's output while carrying low body fat. Body composition measurement is the appropriate tool there.