Ideal Weight Calculator

There is no single "ideal weight" — different formulas give different answers, all of them clinically valid for different purposes. This calculator shows results from four widely-used methods plus the NHS-aligned BMI range, so you can see the spread of reasonable targets for your height and pick one that matches your build and health goals. The Devine formula (1974) is the most widely used in clinical medicine for drug dosing calculations: men 50 kg + 2.3 kg per inch above 5 feet; women 45.5 kg + 2.3 kg per inch above 5 feet. The Robinson formula (1983) revised Devine slightly to better match average body composition: men 52 kg + 1.9 kg per inch above 5 feet; women 49 kg + 1.7 kg per inch above 5 feet. The Miller formula (1983) gives slightly higher targets, accommodating modern populations and dropping rates per inch differently for the two sexes. The Hamwi formula (1964) is the simplest and oldest: men 48 kg + 2.7 kg per inch above 5 feet; women 45.5 kg + 2.2 kg per inch above 5 feet. None of these formulas explicitly use age or build (small/medium/large frame) — they all assume a "medium frame" adult. For practical use, the BMI-based healthy weight range is the most flexible: anything between BMI 18.5 and 24.9 is considered healthy by the NHS. The midpoint BMI 22 is often cited as the optimum for longevity in population studies. This calculator shows ideal weight per formula plus the full NHS healthy range in your selected units, and highlights how far from each target your current weight (if entered) sits. The spread between formulas can easily be 5-7 kg for the same person — there is no objectively "correct" answer, only ranges. Picking a target near the middle of the NHS range typically gives more flexibility and a more sustainable goal than aiming at the formulas’ minimums. Limits. None of the formulas account for muscle mass, frame size, ethnicity, age or sex-specific body composition variation. They are weight targets, not body composition targets — a 15% body fat athlete at the "Devine ideal" weight is in a very different metabolic state from a sedentary office worker at the same number. NICE recommends combining target weight with waist circumference and percentage body fat goals for a complete picture. Use this calculator for goal-setting, the BMI Calculator for current status, and the Calorie Calculator to plan the deficit (or surplus) needed to move from current to target. For NHS-aligned weight management programmes, GP referral is free in England, Scotland, Wales and Northern Ireland.