Four validated formulas give you a range — not a single number. Because there is no single 'ideal weight.'
Four clinical formulas (Devine, Robinson, Miller, Hamwi) estimate ideal body weight from height and sex. They all give different numbers — the range across all four is more useful than any single result. These formulas don't account for muscle mass, frame size, or fitness level.
Written by Ash K · Last updated: June 2026 · Sources cited below
There is no single "ideal weight." Four widely-used clinical formulas — Devine, Robinson, Miller, and Hamwi — each produce different numbers for the same person. This calculator shows you all four results side by side so you can see the range, not chase a single number.
The honest answer to "how much should I weigh?" is a range, not a target. These formulas provide one input into that range — alongside your body composition, fitness level, and how you actually feel.
Key Takeaway: Four clinical formulas estimate ideal body weight. They all give different numbers — that's by design. The range across all four is more useful than any single result. Enter your height, sex, and frame size. The calculator shows all four estimates plus the range.
Each formula uses height and sex as primary inputs. None account for muscle mass, bone density, age, or fitness level — which is why they're estimates, not prescriptions.
Four Ideal Weight Formulas Compared — For a 5ft 8in Person
| Formula | Year | Men (per inch over 5 ft) | Women (per inch over 5 ft) | Origin |
|---|---|---|---|---|
| Devine | 1974 | 50 kg + 2.3 kg/inch | 45.5 kg + 2.3 kg/inch | Drug dosing in pharmacology |
| Robinson | 1983 | 52 kg + 1.9 kg/inch | 49 kg + 1.7 kg/inch | Medical guidelines revision |
| Miller | 1983 | 56.2 kg + 1.41 kg/inch | 53.1 kg + 1.36 kg/inch | Alternative to Devine for heavier builds |
| Hamwi | 1964 | 48 kg + 2.7 kg/inch | 45.4 kg + 2.2 kg/inch | Dietetics and nutrition planning |
Example — 5'8" (173 cm) woman:
Range: 138–141 lbs. The spread is small for this height, but at taller heights the formulas diverge significantly.
Note: The Devine formula — the most widely used — was originally developed for calculating drug dosages, not defining healthy weight. It was never intended as a weight management tool. Understanding this origin helps put the number in perspective: it's a pharmacological estimate repurposed for nutrition, not a scientifically-derived health target.
Your ideal body weight range should be interpreted as one data point among several. The formulas don't account for:
Muscle mass. A 5'10" man with significant muscle may weigh 200 lbs at 12% body fat — well above any formula's "ideal" but genuinely lean. Our lean body mass calculator and body fat calculator give composition-based assessments.
Frame size. The Hamwi formula allows ±10% adjustment for frame size (add 10% for large frame, subtract 10% for small). Our body frame size calculator can determine your frame.
Age. Healthy weight ranges shift with age. Older adults with slightly higher BMI (25–27) show better mortality outcomes than those at BMI 18.5–22 in some large studies.
Fitness and functionality. A weight at which you sleep well, move comfortably, maintain energy, and meet your physical demands is a better "ideal" than any formula output.
Tip: Use the formula range as a general reference — not a target to hit exactly. If your current weight falls within ±10% of the range and your body composition, energy, and health markers are good, you're likely at a healthy weight regardless of what the formula says.
For clinical settings (particularly drug dosing and nutrition planning), an adjusted body weight calculation is used when actual weight significantly exceeds ideal weight:
Adjusted BW = IBW + 0.4 × (Actual Weight − IBW)
This accounts for the metabolic contribution of excess adipose tissue. Pharmacists and dietitians use adjusted body weight to calculate medication doses and protein requirements for patients above their ideal weight.
Example: IBW = 65 kg, Actual = 100 kg → Adjusted = 65 + 0.4 × (100 − 65) = 65 + 14 = 79 kg
Warning: Ideal body weight formulas were developed on limited, predominantly White populations. They may not accurately represent healthy weight ranges for all ethnicities, body types, or ages. Research increasingly shows that health outcomes correlate more strongly with body composition, fitness level, and metabolic markers than with weight-to-height ratios.
Bottom Line: There is no single ideal weight — four validated formulas give you a range. Use that range as context, not a verdict. Your body composition, fitness, energy, and health markers matter more than matching a formula developed for drug dosing in 1974.
How do I calculate my ideal body weight?
Use the Devine formula (most common): Men = 50 kg + 2.3 kg per inch over 5 feet. Women = 45.5 kg + 2.3 kg per inch over 5 feet. Or use this calculator to see all four formulas compared.
What is the ideal body weight calculation formula?
Four formulas exist (Devine, Robinson, Miller, Hamwi). Each uses height and sex as inputs. The Devine formula is most widely used: IBW = 50 kg + 2.3 kg × (inches over 60) for men, or 45.5 kg + 2.3 kg × (inches over 60) for women.
Is the ideal weight calculator accurate?
These formulas estimate weight ranges based on height and sex only. They don't account for muscle mass, body composition, frame size, or fitness level. They're useful as general references but should not be the sole measure of healthy weight.
What's the difference between ideal weight and BMI?
Ideal weight formulas give a target weight in kg/lbs. BMI gives a weight-to-height ratio. Both are screening tools with similar limitations — neither measures body composition directly. For BMI assessment, see our BMI calculator.
This tool is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your healthcare provider with questions about your health.