Ideal Weight Calculator

An ideal body weight (IBW) calculator estimates a healthy reference weight for someone of your height, sex, and frame size. The concept goes back to insurance-industry actuarial tables from the early 20th century and was later refined into a series of regression-based formulas used in clinical medicine, pharmacy, and fitness coaching.

Because there's no single "correct" formula, this tool reports four classical equations — Robinson, Miller, Devine, and Hamwi — and shows the range. A small/medium/large frame adjustment of ±10% accounts for natural variation in skeletal build that height alone doesn't capture.

A man, 175 cm tall (5'9", or 9 inches over 5 feet), medium frame:

• Robinson: 52 + 1.9 × 9 = 69.1 kg
• Miller: 56.2 + 1.41 × 9 = 68.9 kg
• Devine: 50 + 2.3 × 9 = 70.7 kg
• Hamwi: 48 + 2.7 × 9 = 72.3 kg
• Average: 70.3 kg · Range: 68.9 – 72.3 kg

For comparison, a healthy BMI range (18.5–24.9) at 175 cm gives 56.7–76.3 kg — a wider range that the IBW formulas all fall inside. A small-framed version of this person would target 62–65 kg; large- framed, 76–80 kg.

• Setting a long-term weight goal — pick a target inside the IBW range that matches your activity level.
• Clinical drug dosing — many medications use Devine IBW rather than actual weight to avoid overdosing in people carrying excess fat mass.
• Sports weight classes — wrestlers, boxers, and rowers can use IBW as a sanity check for safe walking-around weight.
• Recovering from weight loss or eating disorders — clinicians often use IBW (typically 90% of Devine) as a treatment goal.
• Pediatric and geriatric care — IBW is part of standardized nutrition assessment for under-/over-nourished patients.

• Treating IBW as a single number. Use the range, not a specific kilogram. Real-world healthy weight varies by ±5 kg around the average.
• Ignoring body composition. A muscular 80 kg lifter may be 10 kg above "ideal" while having lower health risk than a sedentary person at IBW.
• Skipping frame size. A small-framed person at large-frame IBW will look and feel overweight; the opposite is also true.
• Using older formulas in isolation. Hamwi (1964) systematically gives slightly higher numbers than modern formulas. Cross-check with Robinson or Miller.
• Confusing IBW with BMI targets. They're different tools — IBW is a single formula output; BMI gives a healthy range. Use both together for a full picture.