An ideal weight calculator uses your height and sex to estimate a target body weight using one or more established clinical formulas. This calculator uses the four most widely cited formulas -- Devine (1974), Robinson (1983), Miller (1983), and Hamwi (1964). Each formula takes height in inches above 5 feet as its primary variable and adds a per-inch increment for every inch above that baseline. The result is expressed in kilograms, or converted to pounds for imperial users.

Devine (1974): For men: IBW = 50 kg + 2.3 kg per inch above 5 ft. For women: IBW = 45.5 kg + 2.3 kg per inch above 5 ft. It was originally developed for drug dosing in clinical pharmacology -- particularly for medications where dose calculation based on actual weight in obese patients would lead to over-dosing. It remains the most commonly used formula in hospital settings today.

Hamwi (1964): For men: IBW = 48 kg + 2.7 kg per inch above 5 ft (or 106 lbs + 6 lbs per inch). For women: IBW = 45.4 kg + 2.27 kg per inch above 5 ft (or 100 lbs + 5 lbs per inch). The Hamwi formula is the oldest of the four and is widely used in dietetics and nutritional counselling for establishing caloric goals.

No single formula is universally most accurate -- each was developed for different populations and purposes. Studies comparing the formulas show similar estimates for average-height adults but increasing divergence at extreme heights. The Devine formula is most commonly cited in clinical settings. Many practitioners use the average of all four formulas as a balanced reference range rather than relying on any one estimate.

Not exactly. IBW formulas produce a single target, while a healthy BMI weight range (18.5-24.9) covers roughly 10-15 kg for a given height. Formula results typically correspond to a BMI of about 20-23 -- within the healthy range but on the lower end. Reaching the formula target is not necessary for good health; staying within the healthy BMI window is a more practical goal for most people.

Standard formulas (Devine, Robinson, Miller, Hamwi) do not account for body frame size, muscle mass, or athletic build. They provide a statistical average target weight based on height and sex only. A large-framed or muscular person may reasonably weigh 10-15% above the formula estimate while being perfectly healthy. Body fat percentage testing gives a more individualised picture of body composition.