Ideal Weight Calculator
Four classic formulas and the healthy BMI band, side by side. The truth is a range, not a single magic number.
Why four formulas disagree
Each formula was fitted to a different clinical population decades apart — Hamwi in 1964, Devine in 1974, Robinson and Miller in 1983. They were designed for drug dosing, where a standardised weight matters more than individual body composition. The spread between them for a given height is typically 4–7 kg, and that spread is the message: there is no single correct weight for a height.
A better question than "what should I weigh?"
Weight is one input among several. The combination that predicts health well is:
- A weight inside the healthy BMI band — or just above it with visible muscle mass;
- A waist under 94 cm (men) / 80 cm (women), because abdominal fat is the kind that causes trouble;
- Stable, not yo-yoing — repeated large swings are harder on the body than a steady slightly-higher weight;
- Maintained on habits you can keep — a weight that needs permanent hunger is not your ideal weight.
Muscular people should ignore these formulas entirely. They pre-date modern training and will call a lean 90 kg lifter overweight at any height. Body fat percentage is the number that matters there — use the body fat calculator.
Getting there
Pick the nearest edge of the healthy range, not the middle, as a first target. Then work out the calories that take you there with the calorie calculator — about 0.5 kg a week is the pace that tends to stick.
Frequently asked questions
Which formula should I trust?
None individually — the healthy BMI band is better evidenced than any of them. The formulas are shown because doctors still quote them and it helps to see how much they disagree.
Does frame size matter?
A little. Wrist and elbow measurements shift the estimate by a few kilograms either way, which is roughly the spread between the four formulas anyway.
Is the middle of the range best?
Not necessarily. Anywhere in the band with a healthy waist measurement is fine; where you personally feel and perform best decides the rest.