Ideal Weight Calculator
Calculate your ideal weight range by height and gender using Devine, Hamwi and BMI formulas.
This tool is for informational purposes only. Consult a doctor or dietitian for health decisions.
How Is Ideal Weight Determined?
The question of ideal weight seems simple, but the answer is not a single number — it is a range. The healthy weight range for your height is calculated differently by the Devine, Hamwi and BMI formulas. This tool presents all three together so you can see a realistic target range instead of being tied to a single figure.
What Is Ideal Weight and Why Is It Not a Single Number?
In medicine, 'ideal weight' refers to the weight range thought to minimise health risks for a given height. Different formulas take different approaches: the Devine and Hamwi formulas were originally developed to calculate clinical drug dosages, while the BMI range has become widespread for public health purposes.
For example, for a male who is 180 cm tall, the Devine formula suggests 75.0 kg, the Hamwi formula suggests 77.3 kg, and the BMI range is 59.9–80.7 kg. This variation shows that formulas are estimation tools.
The Effect of Age on Ideal Weight
The Devine and Hamwi formulas do not directly account for age. However, muscle mass decreases and fat tissue ratio changes at older ages. Combining formula outputs with the advice of a doctor or dietitian becomes more meaningful as you get older.
Formulas and Logic
The tool first converts your height from centimetres to inches, then calculates the excess over 60 inches (5 feet ≈ 152 cm). Devine (male): 50 + 2.3 × (inches over); for females the base is 45.5. Hamwi (male): 48 + 2.7 × (inches over); for females the base is 45.5 and the multiplier is 2.2. The BMI range is obtained by multiplying the 18.5 and 24.9 thresholds by the square of the height in metres.
Example Scenarios
| Profile | Devine | Hamwi | BMI Range |
|---|---|---|---|
| Male · 170 cm | 65.9 kg | 66.7 kg | 53.5 – 71.9 kg |
| Male · 180 cm | 75.0 kg | 77.3 kg | 59.9 – 80.7 kg |
| Female · 160 cm | 52.4 kg | 52.1 kg | 47.4 – 63.7 kg |
| Female · 165 cm | 56.9 kg | 56.4 kg | 50.4 – 67.8 kg |
What Should You Do If You're Not at Your Ideal Weight?
The three values from the tool complement each other. While Devine and Hamwi provide single-point estimates, the BMI range shows you a broader safe zone. In practice, aiming to stay between the lower and upper bounds of the BMI range is the most comprehensive approach.
If your current weight is well above this range, making progress in small steps offers a sustainable path. If you are below the range, remember that being underweight also carries its own health risks. In either case, the advice of a dietitian or doctor will be a valuable guide.