Ideal Weight Calculator

What Is the Ideal Weight Calculator?

Ideal weight refers to a weight range that is associated with the lowest risk of weight-related health problems for a person of a given height, sex, and age. Rather than a single target number, it is more accurately thought of as a range within which most people tend to have the best health outcomes. The National Heart, Lung, and Blood Institute uses BMI-based weight ranges as the primary reference point for healthy weight, while the CDC recommends using BMI alongside waist circumference for a more complete assessment of weight-related risk.

This calculator works out your ideal weight range using four well-established formulas: the Hamwi formula, the Devine formula, the Robinson formula, and the Miller formula. Each was set out at different points in medical history and uses slightly different assumptions, which is why their results vary. Presenting all four alongside the BMI-based range gives you a broader picture than any single formula could.

How to Use the Ideal Weight Calculator

1. Enter your height using the unit toggle to switch between centimetres and feet and inches.
2. Select your sex, as the formulas differ between men and women.
3. Optionally enter your age, which is used to adjust the result for older adults who may have a different body composition than younger people at the same height.
4. The calculator returns a range based on multiple formulas and highlights the BMI-based healthy weight range for your height.
5. For more context, compare this result with the BMI Calculator and the Body Fat Calculator.

The Formulas Explained

The four principal ideal weight formulas each take a somewhat different approach. All are designed for adults and use height as the primary input, with adjustments for sex.

Hamwi (1964)
Men: 48.0 kg + 2.7 kg per cm above 152.4 cm
Women: 45.5 kg + 2.2 kg per cm above 152.4 cm

Devine (1974)
Men: 50.0 kg + 2.3 kg per cm above 152.4 cm
Women: 45.5 kg + 2.3 kg per cm above 152.4 cm

Robinson (1983)
Men: 52.0 kg + 1.9 kg per cm above 152.4 cm
Women: 49.0 kg + 1.7 kg per cm above 152.4 cm

Miller (1983)
Men: 56.2 kg + 1.41 kg per cm above 152.4 cm
Women: 53.1 kg + 1.36 kg per cm above 152.4 cm

The BMI-based range is derived from the WHO healthy range of 18.5 to 24.9, applied to your specific height to give the corresponding weight range in kilograms.

Key Considerations

These formulas were originally developed in clinical contexts for dosing medications and setting nutritional targets in hospital settings, not as personal fitness targets. Given that, they have significant limitations when applied to the general population. They do not account for body composition, muscle mass, bone density, or ethnic background, all of which influence what a healthy weight looks like for any individual.

On top of that, the concept of a single ideal weight has largely been replaced in clinical practice by weight ranges and body composition assessments. Two people of the same height can have the same weight but very different body compositions and risk profiles. A heavily muscular person may weigh more than any of these formulas suggest without carrying excess fat, while someone with a lower weight may still carry a higher-than-healthy proportion of body fat.

Age is also a factor that these older formulas largely overlooked. As people age, muscle mass tends to decline and fat mass tends to increase even when total weight stays constant. As a result, what constitutes a healthy weight shifts somewhat with age, particularly above 60.

What to Do With Your Result

Use the ideal weight range as one reference point among several, not as a precise target. If your current weight is within or close to the calculated range, the emphasis should be on maintaining a balanced diet, staying physically active, and monitoring other health markers such as blood pressure and blood glucose rather than focusing purely on weight.

If your weight is significantly above the range, look into the Calorie Calculator to figure out a sustainable daily energy target, and consider speaking to a GP or dietitian for personalised guidance. If it is significantly below the range, that equally warrants a conversation with a healthcare professional.

Conclusion

The ideal weight calculator gives you a practical reference range based on multiple well-established clinical formulas. It is a starting point for thinking about where your weight sits relative to broadly accepted health benchmarks, not a definitive target. Used alongside BMI and body fat percentage, it gives you a more rounded view of your body composition than any single figure could provide on its own.