What Is Ideal Body Weight?
Ideal body weight (IBW) is a clinically derived estimate of the weight considered healthiest for a person of a given height and gender. The concept dates to the 1950s when life insurance companies analyzed mortality data to identify the weights associated with the lowest death rates. That work eventually inspired medical researchers to create mathematical formulas doctors could use in practice.
Today, four formulas dominate clinical and popular use: Hamwi (1964), Devine (1974), Robinson (1983), and Miller (1983). Each was developed independently, using different study populations and purposes. As a result, they produce different — sometimes meaningfully different — estimates for the same person. Understanding why those differences exist is just as useful as knowing your number.
Disclaimer: Ideal weight formulas are reference tools, not medical advice. If you have health conditions or specific weight-related concerns, consult your healthcare provider before setting weight targets.
The Four Ideal Weight Formulas Compared
All four formulas follow the same structure: a base weight for someone exactly 5 feet (60 inches) tall, plus an increment for every inch over 5 feet. They calculate in kilograms and then convert to pounds.
| Formula | Year | Male (kg) | Female (kg) | Original Purpose |
|---|---|---|---|---|
| Hamwi | 1964 | 48 + 2.7 × (H − 60) | 45.5 + 2.2 × (H − 60) | Diabetes dietary planning |
| Devine | 1974 | 50 + 2.3 × (H − 60) | 45.5 + 2.3 × (H − 60) | Drug dosing (anesthesia, chemo) |
| Robinson | 1983 | 52 + 1.9 × (H − 60) | 49 + 1.7 × (H − 60) | Revised population estimate |
| Miller | 1983 | 56.2 + 1.41 × (H − 60) | 53.1 + 1.36 × (H − 60) | Revised population estimate |
Where H = height in inches. The result in kilograms is multiplied by 2.20462 to convert to pounds.
Frame Size Adjustment
Body frame — determined by bone structure and wrist circumference — affects how much a person naturally weighs at a given height. All four formula results are adjusted as follows:
| Frame Size | Adjustment | Wrist (Men) | Wrist (Women) |
|---|---|---|---|
| Small | −10% | < 6.5 in | < 6.0 in |
| Medium | None | 6.5–7.5 in | 6.0–6.25 in |
| Large | +10% | > 7.5 in | > 6.25 in |
Step-by-Step Worked Examples
Example 1 — 5'8" Male, Medium Frame (68 inches)
Inches over 60 = 8
- Hamwi: (48 + 2.7 × 8) × 2.20462 = 69.6 kg = 153 lbs
- Devine: (50 + 2.3 × 8) × 2.20462 = 68.4 kg = 151 lbs
- Robinson: (52 + 1.9 × 8) × 2.20462 = 67.2 kg = 148 lbs
- Miller: (56.2 + 1.41 × 8) × 2.20462 = 67.5 kg = 149 lbs
Range: 148–153 lbs. Average: ~150 lbs. Healthy BMI range for 5'8": 125–164 lbs. All formula results fall well within the healthy range.
Example 2 — 5'4" Female, Small Frame (64 inches)
Inches over 60 = 4. Frame multiplier = 0.9 (small).
- Hamwi: (45.5 + 2.2 × 4) × 0.9 × 2.20462 = 49.3 kg = 109 lbs
- Devine: (45.5 + 2.3 × 4) × 0.9 × 2.20462 = 48.8 kg = 108 lbs
- Robinson: (49 + 1.7 × 4) × 0.9 × 2.20462 = 50.6 kg = 112 lbs
- Miller: (53.1 + 1.36 × 4) × 0.9 × 2.20462 = 53.2 kg = 117 lbs
Range: 108–117 lbs. The small frame adjustment reduces all estimates by 10%. Healthy BMI range for 5'4": 110–145 lbs. Note: the lower formula estimates (108–109 lbs) fall slightly below the healthy BMI minimum of 110 lbs — a reminder to cross-check formula results against the BMI range.
Example 3 — 6'1" Male, Large Frame (73 inches)
Inches over 60 = 13. Frame multiplier = 1.1 (large).
- Hamwi: (48 + 2.7 × 13) × 1.1 × 2.20462 = 88.9 kg = 196 lbs
- Devine: (50 + 2.3 × 13) × 1.1 × 2.20462 = 85.2 kg = 188 lbs
- Robinson: (52 + 1.9 × 13) × 1.1 × 2.20462 = 83.7 kg = 185 lbs
- Miller: (56.2 + 1.41 × 13) × 1.1 × 2.20462 = 79.4 kg = 175 lbs
Range: 175–196 lbs — a 21 lb spread. The large frame adjustment adds 10% to each result. Healthy BMI range for 6'1": 140–189 lbs. The Hamwi estimate (196 lbs) slightly exceeds the upper BMI boundary, illustrating how formula results diverge more at taller heights.
Formula Comparison at Common Heights
The table below shows average ideal weight (average of all four formulas, medium frame) at common heights to give a quick reference:
| Height | Male Average IBW | Female Average IBW | Healthy BMI Range (Male) | Healthy BMI Range (Female) |
|---|---|---|---|---|
| 5'0" (60 in) | 110 lbs | 100 lbs | 97–130 lbs | 97–130 lbs |
| 5'4" (64 in) | 133 lbs | 120 lbs | 110–145 lbs | 110–145 lbs |
| 5'6" (66 in) | 143 lbs | 129 lbs | 118–154 lbs | 118–154 lbs |
| 5'8" (68 in) | 153 lbs | 138 lbs | 125–164 lbs | 125–164 lbs |
| 5'10" (70 in) | 163 lbs | 148 lbs | 132–174 lbs | 132–174 lbs |
| 6'0" (72 in) | 173 lbs | 158 lbs | 140–184 lbs | 140–184 lbs |
| 6'2" (74 in) | 184 lbs | 168 lbs | 148–194 lbs | 148–194 lbs |
Averages rounded to nearest pound. Medium frame assumed. Healthy BMI range = 18.5–24.9.
The History Behind Each Formula
Hamwi (1964) — The Original
G.J. Hamwi published the first widely cited ideal weight formula in 1964 in the context of managing diet for diabetic patients. The formula is the simplest in concept: 106 lbs for 5 feet of height in men (100 lbs for women), plus 6 lbs per additional inch (5 lbs for women). The kilogram version used in the calculator is mathematically equivalent. Hamwi gives the highest per-inch increments for men of the four formulas, producing the largest estimates at tall heights.
Devine (1974) — The Clinical Standard
Dr. B.J. Devine published his formula specifically to address a practical clinical problem: calculating appropriate doses of medications like gentamicin and digoxin that distribute primarily into lean body mass rather than body fat. Using total body weight for obese patients would dramatically overdose them; using IBW instead provides a safer proxy for lean mass. The Devine formula quickly became the default in clinical software and remains the most commonly used IBW formula in healthcare settings globally.
Robinson and Miller (Both 1983)
In 1983, two independent research teams published competing refinements to the Devine formula. Robinson et al. used a different reference population and produced a formula with a higher base weight but smaller per-inch increment. Miller et al. produced a formula with an even higher base weight and the smallest per-inch increment of all four. These differences mean Robinson and Miller produce lower estimates than Hamwi and Devine at tall heights, but higher estimates at short heights — which is why looking at all four together gives a more complete picture than any single formula.
Key Limitations to Understand
Body Composition Is Invisible to These Formulas
All four formulas are blind to what your body is made of. A 5'10" male bodybuilder with 190 lbs of lean muscle and 8% body fat receives the same IBW estimate as a sedentary 5'10" male with 35% body fat and 165 lbs of lean mass. For athletes and highly muscular individuals, body fat percentage is a far more meaningful metric than any height-based ideal weight formula.
The Formulas Were Derived from Limited Populations
All four formulas were developed using predominantly white adult populations in the United States or Europe. Research has since shown that the relationship between body weight, body fat, and health risk varies by ethnicity. For example, Asian populations face elevated cardiometabolic risk at lower BMI thresholds than the formulas assume. No universal ideal weight formula exists that works equally well across all ethnic backgrounds.
They Are Least Accurate Outside 5'0"–6'3"
The linear per-inch increment structure breaks down at extremes. For someone 4'10" tall, the base weight minus one full increment may fall below a healthy BMI threshold. For someone 6'5" tall, the cumulative increments may suggest a weight above what their cardiovascular system can healthily support. Outside the 5'0"–6'3" range, rely more on the healthy BMI range than on formula estimates.
Ideal Weight vs. Healthy Weight vs. Goal Weight
These three terms are often used interchangeably but mean different things:
- Ideal body weight (IBW): A formula-derived single number based on height and gender. Clinically useful for drug dosing; less meaningful as a personal weight target.
- Healthy weight range: The weight range corresponding to a BMI of 18.5–24.9, derived from large epidemiological studies linking BMI to disease risk. A range rather than a single number — and a more appropriate target for most people.
- Goal weight: Your personal target, ideally set in collaboration with a healthcare provider. Should fall within the healthy BMI range, be achievable through sustainable habits, and account for individual factors like fitness level and health history.
For most people, a goal weight anywhere in the healthy BMI range — not necessarily the specific IBW number — is the right target. The formulas are a starting point for the conversation, not the final answer.
How to Use the Ideal Weight Calculator
Use the CalcCenter Ideal Weight Calculator to see results from all four formulas at once:
- Select biological sex — the formulas use different base weights and per-inch increments for men and women.
- Enter height in inches — convert feet and inches: multiply feet × 12 and add remaining inches (e.g., 5'9" = 69 inches).
- Select frame size — use the wrist circumference method described above if unsure. When in doubt, choose medium.
The calculator returns all four formula results plus the healthy BMI range for your height. The spread between the four results is a built-in uncertainty range — your true ideal weight almost certainly falls somewhere within that spread.
For a complete picture of your health, combine IBW with BMI, body fat percentage, and your Total Daily Energy Expenditure (TDEE) to understand both your weight target and the calorie balance needed to reach and maintain it.
Key Takeaways
- Four formulas — Hamwi, Devine, Robinson, Miller — each produce slightly different ideal weight estimates; the spread is typically 10–20 lbs.
- The Devine formula is the clinical standard, used most often for drug dosing calculations in hospitals and pharmacies.
- Frame size (small/medium/large) adjusts all estimates by ±10% based on bone structure.
- Formula results are least reliable outside the 5'0"–6'3" range; use the healthy BMI range as a cross-check.
- Athletes and muscular individuals should prioritize body fat percentage over IBW formulas.
- A realistic personal goal weight is one within the healthy BMI range (18.5–24.9), achievable through sustainable habits, and confirmed appropriate by your healthcare provider.