Why a range, not a number
Older 'ideal weight' formulas give a single figure, but health is better described by a range, because two people of the same height can be perfectly healthy at different weights depending on muscle, frame and body composition. This calculator shows the Devine formula — long used clinically, for example to dose medication — next to the weight range that maps to a healthy body-mass index of 18.5 to 24.9. The BMI range is the more meaningful target for most people; the Devine figure is a useful reference point that sits inside it.
The Devine formula
Dr B. J. Devine proposed his formula in 1974: 50 kg plus 2.3 kg for every inch over five feet for men, and 45.5 kg plus 2.3 kg per inch over five feet for women. It was designed for clinical use rather than as a fitness goal, and it tends to read a little lean for muscular or larger-framed people. It is included here because it is widely recognised and gives a quick single-number reference, but treat the healthy-BMI range as the practical target band.
The limits of height-based targets
Any weight target based on height alone ignores body composition. Muscle is denser than fat, so a lean, muscular athlete can weigh above the 'healthy' range and carry very little fat, while someone within the range can still have high body fat. That is why body fat percentage and waist measurements add important context. Use the ideal-weight range as a sensible starting frame, then look at how you feel, how your clothes fit and your body fat to judge whether your weight is right for you.
Reaching and holding a healthy weight
If you are outside your healthy range, aim for gradual change — roughly half a kilogram a week — driven by a modest calorie deficit or surplus plus strength training to protect muscle. Crash targets rarely hold. Use the TDEE calculator to set calories and the body-fat calculator to check that changes are coming from fat, not muscle. These tools use standard, published formulas and the figures you enter. They are estimates for general fitness and planning, not a medical assessment — check with a doctor or dietitian before making health decisions.
Frequently asked questions
How is ideal weight calculated?
This tool shows two references: the Devine formula (50 kg for men or 45.5 kg for women, plus 2.3 kg per inch over five feet) and the weight range for a healthy BMI of 18.5–24.9 at your height.
Which number should I aim for?
The healthy-BMI range is the practical target for most people. The Devine figure is a single-number reference that sits inside it and can read slightly lean for muscular builds.
Does ideal weight account for muscle?
No. Height-based targets cannot distinguish muscle from fat, so athletes may sit above the range while still lean. Check body fat percentage for a fuller picture.
Is BMI a good measure of ideal weight?
It is a useful population screen but imperfect for individuals, especially the very muscular. Pair it with body fat and waist measurements rather than relying on it alone.