What “ideal weight” really means
Ideal weight is one of those phrases that sounds precise but isn’t. There is no single correct number for a given height. What does exist is a healthy weight range — a band within which people of your height tend to carry the lowest health risk. This calculator gives you that range from your sex and height, and adds three classic clinical formulas that doctors have leaned on for decades as a quick reference point.
The most widely accepted way to estimate a healthy weight today is the Body Mass Index (BMI). A BMI between 18.5 and 24.9 is considered normal weight for adults, so rearranging the formula to solve for weight gives you a realistic band for your height. Everything is computed in your browser — your numbers are never stored or sent anywhere.
How to use the calculator
- Pick your sex — the classic formulas use different constants for men and women.
- Enter your height in centimetres (for example, 165).
- Read the healthy BMI range, shown as the main result.
- Compare it with the Devine, Robinson and Miller formulas, each of which returns a single reference figure.
- Tap copy if you want to save the range for your doctor or your own records.
How it is worked out
The main range comes straight from BMI. You solve the BMI equation for weight at each healthy boundary:
- Minimum weight:
18.5 × height²(height in metres) - Maximum weight:
24.9 × height²
The classic formulas start from a base for the first 152 cm (5 feet) of height and add a fixed amount per extra inch. The best known is Devine: men = 50 + 2.3 × (inches over 5 feet) and women = 45.5 + 2.3 × (inches over 5 feet). Robinson and Miller are later revisions with slightly different constants.
Worked example
Take a woman who is 165 cm tall. Her height is 165 ÷ 100 = 1.65 m, so 1.65² = 2.7225.
- Minimum healthy weight: 18.5 × 2.7225 = 50.4 kg
- Maximum healthy weight: 24.9 × 2.7225 = 67.8 kg
For the Devine formula, 165 cm is 65.0 inches, or 5.0 inches over 5 feet. So 45.5 + 2.3 × 5.0 ≈ 56.9 kg, which sits comfortably inside the BMI band. Robinson gives 57.4 kg and Miller 59.8 kg for the same person.
Healthy range by height (women)
| Height (cm) | BMI range (kg) | Devine (kg) |
|---|---|---|
| 150 | 41.6 – 56.0 | 43.3 |
| 155 | 44.4 – 59.8 | 47.9 |
| 160 | 47.4 – 63.7 | 52.4 |
| 165 | 50.4 – 67.8 | 56.9 |
| 170 | 53.5 – 72.0 | 61.4 |
| 175 | 56.7 – 76.3 | 66.0 |
Frequently asked questions
Which formula is the best one?
None of them is perfect. Devine, Robinson and Miller were built to help calculate drug doses, not to judge your body, and each collapses everything into one number that ignores your build. To gauge your own weight, the BMI range is the more useful reference, because it accepts that health lives in a band rather than at a single point.
Does ideal weight depend on age?
The standard healthy BMI band (18.5 to 24.9) is defined for adults and does not shift with age. That said, many clinicians are comfortable with a little extra weight in older adults, since a small reserve is linked to better recovery from illness. For children and teenagers, BMI is read against separate percentile charts instead.
Why do athletes weigh more without being overweight?
Because muscle is denser than fat — it weighs more for the same volume. A heavily muscled athlete can land above the BMI range while carrying very little body fat. Neither BMI nor these formulas can tell muscle, fat, bone and water apart, so they underestimate how healthy well-trained people actually are.
Does this replace medical advice?
No. This is an informational tool. Your real healthy weight depends on your body composition, medical history and habits. For any decision about your health, talk to a professional.