Ideal Weight Calculator

"Ideal body weight" (IBW) is a clinical concept used by physicians and pharmacists — most often for drug dosing, ventilator settings, and nutritional planning — rather than a fitness or aesthetic target. Several formulas exist because none has been shown to be definitively superior for the general population.

The Devine formula (1974) is the most widely used in clinical medicine. Robinson (1983), Miller (1983), and Hamwi (1964) are alternatives that produce slightly different ranges; averaging all four gives a sensible middle estimate. All four anchor a base weight at 5 ft of height and add a fixed amount per inch above that.

For most healthy adults, the WHO healthy BMI range (18.5–24.9) is a more practical target than any single IBW number. Use the IBW figures as a reference point; use BMI plus body composition and how you feel as your real guide.

"Ideal weight" formulas (Devine, Robinson, Miller, Hamwi) were originally derived from insurance-actuarial data and pharmacology dosing tables in the mid-20th century. They give similar but not identical results, mostly within a 10-pound range for the same height. Modern obesity medicine has largely shifted to using BMI ranges plus body-composition measures rather than a single ideal-weight number — body composition and waist circumference predict health outcomes better than weight alone.

Body composition matters more than the scale. A 180-pound male at 12% body fat is in completely different shape than a 180-pound male at 28% body fat, despite identical weight and BMI. DEXA scans, BodPod and hydrostatic weighing are the gold standards for body-fat measurement; bioimpedance scales and skinfold calipers are cheaper but less accurate. The body-fat calculator on this site uses the US Navy method, which is one of the better tape-measure approaches.

Healthy weight ranges shift with age, ethnicity and athletic background. BMI cutoffs developed from white European populations underestimate health risk in South Asian populations and overestimate it in Polynesians. Older adults (65+) actually have better mortality outcomes at BMIs of 25–30 than at lower BMIs, the opposite of what is true for younger adults. Use these calculators as starting points and consult a clinician familiar with your background for personalised targets.

Sustainable weight management is about behaviours and habits, not a target on a scale. People who maintain large weight losses (the National Weight Control Registry has tracked them for decades) almost universally weigh themselves regularly, exercise about an hour daily, eat breakfast and watch less than 10 hours of TV per week. Pick the habits first; the weight number usually follows.