Ideal Body Weight Calculator
Your ideal body weight (IBW) is not one number — it is four clinical formulas that rarely agree, plus the healthy BMI range most doctors actually use. See them all at once.
Last updated October 25, 2026
How to use this calculator
- Choose units and your sex (the formulas differ by sex).
- Enter your height — that is the only measurement these ideal body weight formulas use.
- Compare all four IBW estimates against the healthy BMI range, and remember lean people run heavy on a scale.
The four ideal body weight formulas
Each formula starts from a base weight at 5 ft (152 cm) and adds a fixed amount per inch above it:
| Formula | Men (base + per inch) | Women (base + per inch) | Origin |
|---|---|---|---|
| Devine (1974) | 50.0 kg + 2.30 kg | 45.5 kg + 2.30 kg | Drug dosing |
| Robinson (1983) | 52.0 kg + 1.90 kg | 49.0 kg + 1.70 kg | Revision of Devine |
| Miller (1983) | 56.2 kg + 1.41 kg | 53.1 kg + 1.36 kg | Revision of Devine |
| Hamwi (1964) | 48.0 kg + 2.70 kg | 45.5 kg + 2.20 kg | Clinical nutrition |
How to calculate ideal weight with the Devine formula — worked example
Man, 178 cm, step by step with the Devine formula:
- Convert height to inches over 5 ft: 178 cm ÷ 2.54 = 70.1 in → 70.1 − 60 = 10.1 in over the base.
- Apply Devine (men): 50.0 kg + 2.3 kg × 10.1 = 73.2 kg.
- Cross-check the other formulas: Robinson 71.2 kg · Miller 70.4 kg · Hamwi 75.2 kg — all four land within ~5 kg.
- Report as a range: the honest answer is not one number but the 70–75 kg band, with the healthy-BMI range (58.6–78.7 kg for this height) as the practical target.
The same three lines work for women with the female constants (Robinson: 49.0 + 1.7 × inches over 5 ft). The calculator above runs all four at once, in kg or lb.
Note what they ignore: muscle mass, bone structure and body composition. A weightlifting 180 cm man at 15% body fat will blow past every formula and still be perfectly healthy. Treat the numbers as rough anchors, and prefer body-fat percentage or waist-to-height ratio as your real compass.
Clinical variants: Adjusted & Percent IBW
Two derived numbers you will meet in medical calculators (MDCalc and friends):
Adjusted body weight (AdjBW) = IBW + 0.4 × (actual weight − IBW)AdjBW is used for drug dosing in obesity: actual weight overestimates the dose, IBW underestimates it, and 0.4 × the excess is the common compromise. Example: a 100 kg patient with an IBW of 70 kg gets dosed on 70 + 0.4 × 30 = 82 kg. Most hospital dosing references round the correction factor to 0.4; some chemotherapy protocols use 0.33.
Percent IBW (%IBW) = actual weight ÷ IBW × 100Classic clinical bands: <80% severely underweight, 80–90% underweight-ish, 90–110% normal, 110–120% overweight, >120% obese. Nutrition and renal-dosing references still use it, though body-fat percentage and waist-to-height ratio carry more diagnostic signal today.
Ideal body weight range by height and gender
Quick-reference table: the average of the four formulas for each height, for men and women, plus the healthy weight range (BMI 18.5–24.9) that applies to both:
| Height (cm) | Men — IBW (kg) | Women — IBW (kg) | Healthy range (BMI) |
|---|---|---|---|
| 150 | 49.6 | 46.5 | 42–56 kg |
| 155 | 53.7 | 50.2 | 44–60 kg |
| 160 | 57.8 | 53.9 | 47–64 kg |
| 165 | 61.9 | 57.7 | 50–68 kg |
| 170 | 65.9 | 61.4 | 53–72 kg |
| 175 | 70.0 | 65.1 | 57–76 kg |
| 180 | 74.1 | 68.8 | 60–81 kg |
| 185 | 78.2 | 72.5 | 63–85 kg |
| 190 | 82.3 | 76.3 | 67–90 kg |
| 195 | 86.4 | 80.0 | 70–95 kg |
| 200 | 90.5 | 83.7 | 74–100 kg |
Male/female columns are the average of Devine, Robinson, Miller and Hamwi. The healthy range column is identical for both sexes because BMI depends only on height and weight.
BMI vs ideal body weight — which should you use?
They answer different questions, and the World Health Organization's own framing helps: WHO defines a healthy weight as a BMI of 18.5–24.9 — a range tied to health outcomes. The IBW formulas are older clinical tools built for drug dosing and nutrition planning, not health classification.
| BMI (healthy range) | Ideal body weight (formulas) | |
|---|---|---|
| Question it answers | "Is my weight in the healthy band for my height?" | "What single weight should I target?" |
| Output | A range (~19 kg wide at any height) | One number per formula (4 numbers total) |
| Backed by | WHO / outcome data | Clinical convention (dosing, nutrition) |
| Blind spot | Can't see muscle vs fat | Can't see muscle vs fat and ignores range |
| Best used as | Health screening anchor | Goal-setting starting point |
Practical answer: set your goal inside the BMI healthy range, pick your starting weight from the IBW band, and judge progress with body-fat percentage or waist-to-height ratio — the two measures that can tell muscle from fat.
Frequently asked questions
How much should I weigh?
The most defensible single answer is your healthy BMI range — roughly 18.5 × height² to 24.9 × height² in kg (shown in your result). Add the four IBW formulas as cross-checks. If you train seriously, aim by body-fat percentage instead and let the scale float.
Why do the four formulas give different answers?
They were derived from different populations and for different jobs — Devine for medication dosing, Hamwi for clinical nutrition. A 3–6 kg spread across them is normal.
What is IBW used for in medicine?
Ideal body weight traces back to dosing and equipment sizing — Devine (1974) was built for drug dosages, and IBW still standardises ventilator settings and chemotherapy doses. That clinical origin is why each formula looks arbitrary: it was tuned for a job, not for aesthetics.
What if I am shorter than 5 ft?
The formulas still compute (they simply subtract from the base weight), but accuracy drifts at the extremes of height. The BMI range remains valid.
Should I adjust for my frame size?
A quick heuristic: wrap your thumb and middle finger around your opposite wrist — overlapping fingers suggest a smaller frame, non-touching a larger one. Then apply the classic ±10% convention if it helps.