Ideal Body Weight

Overview

Ideal body weight (IBW) formulas estimate a healthy target weight based on height and biological sex. They originated in pharmacology and clinical medicine, where drug dosages and ventilator settings sometimes need a stable reference rather than the patient's actual scale weight. Today they are also widely used as a starting target for weight-management conversations.

This tool reports four well-known IBW estimates side by side — Devine, Robinson, Miller, and Hamwi — because no single formula is universally accepted. Each was fit to a different population, and the four together provide a sensible range rather than a single number. For most adults the spread is only a few kilograms.

How it works

All four formulas use a base weight at five feet of height, plus a per-inch adjustment for additional height:

• Devine (1974): men 50 + 2.3 × (height_in − 60); women 45.5 + 2.3 × (height_in − 60).
• Robinson (1983): men 52 + 1.9 × (height_in − 60); women 49 + 1.7 × (height_in − 60).
• Miller (1983): men 56.2 + 1.41 × (height_in − 60); women 53.1 + 1.36 × (height_in − 60).
• Hamwi (1964): men 48 + 2.7 × (height_in − 60); women 45.5 + 2.2 × (height_in − 60).

Inputs in centimetres are converted to inches first. The results are then often shown alongside a BMI-based range (a healthy BMI of 18.5–24.9 gives a weight range for the user's height) for additional context. None of these formulas accounts for frame size, muscle mass, or body composition.

Examples

• A 175 cm (68.9 in) man — Devine: 70.5 kg, Robinson: 68.9 kg, Miller: 68.8 kg, Hamwi: 72.0 kg. Average around 70 kg.
• A 160 cm (63 in) woman — Devine: 52.4 kg, Robinson: 54.1 kg, Miller: 57.2 kg, Hamwi: 52.1 kg.
• A 190 cm (74.8 in) man — Devine: 84.0 kg, Robinson: 80.1 kg, Miller: 77.1 kg, Hamwi: 88.0 kg. Wider spread on tall users.
• A 170 cm (66.9 in) woman — Devine: 61.4 kg, Robinson: 60.7 kg, Miller: 62.5 kg, Hamwi: 60.7 kg.

FAQ

Which formula is best?
Devine is most cited in clinical practice; Robinson and Miller often track better in population studies. Use the average for a balanced target.

Why do they all use 60 inches as the anchor?
Five feet is the lower bound of the height range each author used to fit their data, so adjustments are added per inch beyond that.

Is IBW the same as a healthy weight?
Not exactly. Healthy weight is a range, and a muscular person may sit well above IBW with no health concern.

Should athletes use these?
Probably not as a target. Lean muscle pushes weight above IBW without raising body-fat percentage.

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