Enter your height and sex to see a healthy weight range and four classic ideal weight formulas side by side. Use the results as a guide, not a target.
Results are estimates for planning. Check the figures before you make a financial or health decision.
How the Ideal weight works
The main result is the weight range that gives a BMI of 18.5 to 24.9, the NHS healthy range for adults. The tool works out your height in metres and multiplies the square of it by 18.5 and by 24.9.
Below that, four formulas are shown for comparison. Devine, Robinson, Miller and Hamwi were all written for clinical or dosing purposes, and each starts from a base weight for 5 feet (60 inches) of height, then adds a fixed amount for every extra inch. Men and women have different base weights and increments.
- Heights between 1.2 m and 2.3 m are accepted.
- You can enter metric (cm, kg) or imperial (inches, stones).
- The formulas ignore age, muscle, bone structure and ethnicity.
BMI-based ranges cannot tell fat from muscle, and the NHS notes that lower thresholds can apply to people of Black, Asian and other minority ethnic backgrounds. The four formulas often disagree by several kilograms, which is a useful reminder that no single number is right.
Worked example
Using the default values in the calculator above:
| Input | Value |
|---|---|
| Units | Metric (cm, kg) |
| Sex | Female |
| Height | 170 |
Healthy weight range (BMI 18.5 to 24.9): 53.5 kg to 72 kg
| Devine formula | 61.4 kg |
|---|---|
| Robinson formula | 60.8 kg |
| Miller formula | 62.5 kg |
| Hamwi formula | 60.7 kg |
Tips and common mistakes
Look at the range rather than any one formula. If your current weight sits inside it, there is usually no reason to chase a lower number. If you are well outside it, a GP or practice nurse can look at your waist size, activity and medical history, which matter more than height alone.
If you want to see where you sit now, try the BMI calculator, or Body fat percentage for an estimate that does not treat muscle as fat. This is general information, not medical advice.
Frequently asked questions
What is the healthy weight range for my height?
The tool shows the weights that give a BMI between 18.5 and 24.9 at your height. That is the NHS healthy range for adults.
Why do the four formulas give different answers?
They were developed separately, using different assumptions and different base weights. Differences of several kilograms are normal, which is why a range is more useful than one figure.
Is ideal weight the same for everyone of my height?
No. Muscle, frame size, age and ethnic background all affect what is healthy for you. Talk to a doctor or nurse if you are unsure.
Guides that help
- BMI explained: what it tells you and what it doesn't
- Body fat percentage: how it's measured and what's typical