A healthy weight range is the span of weights for your height that sits inside the NHS healthy BMI band of 18.5 to 24.9. For an adult who is 170 cm (about 5 ft 7 in) tall, that is roughly 53.5 kg to 72 kg, or 8 st 6 lb to 11 st 5 lb. It is a screening range, not a personal target, so where you sit inside it, and whether you need to be inside it at all, depends on more than a number.
Note: this is general information, not medical advice. A healthy weight range is a population guide and cannot diagnose anything. If you are worried about your weight, or have lost or gained weight without trying, speak to a GP or other health professional.
How a healthy weight range is calculated
The range comes from body mass index (BMI), which compares weight with height. The formula is weight in kilograms divided by height in metres squared. In the NHS adult categories, a BMI under 18.5 is underweight, 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight and 30 or more is obese.
To turn the BMI band into a weight range, you reverse the formula. Multiply the lower and upper BMI by your height in metres squared:
- Lower end: 18.5 × height² (in metres)
- Upper end: 24.9 × height² (in metres)
For a height of 1.70 m, the height squared is 2.89. Then 18.5 × 2.89 is 53.5 kg, and 24.9 × 2.89 is 72.0 kg. That matches the House of Calculator range for 170 cm. Notice that the range is wide: at this height it spans about 18.5 kg (nearly 3 stone). That width is built in because bodies differ in frame size, muscle and fat distribution, and one number would be false precision. Our BMI explained: what it tells you and what it doesn't guide goes through what BMI does and does not tell you.
Healthy weight range by height
The table applies the same two multiplications to a range of adult heights. The stone and pound figures are rounded to the nearest pound, and they are a guide for adults, not for children or teenagers, whose healthy ranges are judged on growth charts.
| Height | Healthy range (kg) | Healthy range (stones and pounds) |
|---|---|---|
| 155 cm (5 ft 1 in) | 44.4 to 59.8 kg | 7 st 0 lb to 9 st 6 lb |
| 160 cm (5 ft 3 in) | 47.4 to 63.7 kg | 7 st 6 lb to 10 st 1 lb |
| 165 cm (5 ft 5 in) | 50.4 to 67.8 kg | 7 st 13 lb to 10 st 9 lb |
| 170 cm (5 ft 7 in) | 53.5 to 72.0 kg | 8 st 6 lb to 11 st 5 lb |
| 175 cm (5 ft 9 in) | 56.7 to 76.3 kg | 8 st 13 lb to 12 st 0 lb |
| 180 cm (5 ft 11 in) | 59.9 to 80.7 kg | 9 st 6 lb to 12 st 10 lb |
| 185 cm (6 ft 1 in) | 63.3 to 85.2 kg | 10 st 0 lb to 13 st 6 lb |
The range is the same for men and women in the BMI method, which is one reason it is a blunt tool. Around 170 cm, each extra 5 cm of height adds roughly 3 kg to the lower end of the range and 4 kg to the upper end. Use the BMI Calculator to get your own result in metric or imperial units, and it will show both your BMI and the range for your height.
Why “ideal weight” formulas give different answers
If you search for an ideal body weight, you will find several formulas rather than one. They were devised for other purposes, such as estimating drug doses, and they all give a single figure rather than a range. The House of Calculator ideal weight tool shows four of them alongside the BMI range so that you can see how much they disagree.
For a height of 170 cm, the results are:
| Method | Female | Male |
|---|---|---|
| BMI healthy range | 53.5 to 72 kg | 53.5 to 72 kg |
| Devine | 61.4 kg | 65.9 kg |
| Robinson | 60.8 kg | 65.2 kg |
| Miller | 62.5 kg | 66.0 kg |
| Hamwi | 60.7 kg | 66.7 kg |
At 160 cm the female Devine figure is 52.4 kg and the male one is 56.9 kg. At 180 cm the male Devine figure is 75.0 kg and the Hamwi figure is 77.3 kg. In every case, the single-number formulas land inside the BMI range, but they differ from each other by several kilograms and by sex. That spread is a hint: no formula is “right”, and “ideal” is better read as “a reasonable middle”. If you are within the BMI range, the difference between a formula’s number and your own weight is not something to worry about on its own.
Where you sit in the range matters less than you think
Being at 19 or 24 on the BMI scale does not mean one is healthier than the other. The range was set so that, across populations, risks of some conditions are lowest within it, but individual health depends on many things: age, family history, fitness, blood pressure, blood sugar, sleep, smoking and alcohol use, and where fat is carried.
A few practical points follow from that:
- A weight that is steady and comfortable is usually a better sign than a precise number. Sudden changes without a reason are worth raising with a GP, whichever end of the range you are at.
- The upper end of the range is not a failure. At 170 cm, 72 kg is a BMI of 24.9 and healthy, whereas 72.5 kg tips the label to overweight, even though a half-kilogram has no medical meaning.
- The lower end deserves the same care. A person at a BMI of 18.6 may be healthy, or may be struggling with eating or illness. The number cannot tell you.
- Age matters. Many health bodies recognise that the best weight for older adults can sit differently, because muscle loss and illness are bigger risks. A professional can advise on this.
The best use of the range is as a prompt. If your weight is well outside it, or heading in one direction, it is a good reason to look more closely, rather than a verdict in itself.
What a healthy weight range misses
BMI is a ratio of weight to height, and it knows nothing about what the weight is made of. That leads to some well-known gaps.
Muscle versus fat. A person who lifts weights or plays a strength sport can be classed as overweight while having low body fat. A worked example: someone who is 180 cm and 90 kg has a BMI of 27.8, which sits in the overweight band, because the healthy ceiling at that height is 80.7 kg. If most of the extra 9 kg is muscle, the label is misleading. In the other direction, an older person who has lost muscle can have a BMI in the healthy range but a high proportion of body fat.
Where fat is stored. Fat around the middle is linked to higher health risk than fat on the hips and thighs. For that reason the NHS also suggests looking at your waist: it points to an increased risk when the waist is above about 94 cm for men and 80 cm for women, though you should check the current NHS guidance for the details. The House of Calculator waist-to-hip tool is another quick check.
Ethnic background. The NHS notes that BMI thresholds can differ for people of Black, Asian and other minority ethnic backgrounds, because health risks can start at a lower BMI. If that applies to you, check the NHS guidance rather than relying on the standard ranges.
Age, height extremes and pregnancy. The adult ranges do not apply to children and teenagers, who are assessed on growth charts. They are also not designed for pregnancy. Very tall and very short adults can also be poorly served, because the squared-height formula is an approximation.
Our Body fat percentage: how it's measured and what's typical guide describes measures that look at body composition, and they are often more informative than BMI for fit, muscular or older people.
What to do if you are outside the range
If your result is outside the healthy range, the sensible response is to gather information, not to panic or crash diet.
- Check the calculation. Make sure your height and weight were entered in the right units. A common error is mixing stones and kilograms.
- Look at the trend. Has your weight been stable for years, or has it moved recently? A change you did not plan is more important than a stable figure.
- Add other measures. Waist measurement, how your clothes fit, fitness, blood pressure and cholesterol all matter. A GP or practice nurse can check them.
- Think about habits, not just weight. Activity, sleep, diet quality and alcohol are things you can influence at any weight.
- Get support. If you want to change your weight, the NHS and your GP can point you to evidence-based support. If you are concerned about disordered eating, speak to a GP promptly, because it is common and treatable.
If you do plan to lose or gain weight, a gradual approach is generally safer than a rapid one. Estimating your energy needs can be a starting point, which our Calories and TDEE: how many calories do you need? guide explains. Often-cited advice is that even a modest loss, in the region of 5% to 10% of body weight, can improve health markers for people with excess weight. At 75 kg, that is about 3.75 to 7.5 kg. Ask your GP what is right for you.
Common mistakes when using a healthy weight range
- Treating it as a goal weight. The range is a screening band. Your own best weight may be anywhere within it, or sometimes just outside it.
- Mixing units. Entering pounds as kilograms, or inches as centimetres, produces a result that is wildly wrong. Check the unit setting first.
- Using it for children. Children and teenagers are assessed differently.
- Chasing the lower end. Reaching a BMI of 18.5 is not a sign of better health than 23, and trying to lower weight to the bottom of the range can be harmful for some people.
- Ignoring muscle. Athletes and people who train regularly should look at measures such as body fat and waist, not only BMI.
- Relying on a single reading. Weight fluctuates by a kilogram or two from day to day with water, food and time of day. Look at the average over a few weeks.
Try the calculator
Enter your height and weight in the BMI Calculator to see your BMI and healthy range, and compare it with the four formula-based figures in the Ideal Weight Calculator.
Frequently asked questions
What is a healthy weight for a 5 ft 7 in woman?
Using the NHS healthy BMI range of 18.5 to 24.9, a woman who is 170 cm (about 5 ft 7 in) falls in the healthy range at roughly 53.5 kg to 72 kg, which is about 8 st 6 lb to 11 st 5 lb. The BMI range is the same for men and women.
Is BMI accurate for everyone?
No. It is a quick screen that does not tell fat from muscle, ignores where fat is carried, and is not designed for children or pregnancy. Thresholds may also differ for some ethnic groups, so use it as a starting point and speak to a health professional about your own situation.
Why do ideal weight formulas disagree?
They were built from different data for different uses, and each produces a single number from height and sex. At 170 cm the male results span about 65 kg to 67 kg and the female results about 61 kg to 62.5 kg, so the formulas differ by a few kilograms. The BMI range is wider and more realistic.
Can I be healthy outside the healthy weight range?
Yes, some people are, particularly very muscular people at the overweight end. Equally, a person inside the range can have health problems. Other measures, such as waist size, fitness and blood tests, add useful information.
How do I convert the healthy range to stones and pounds?
Multiply kilograms by 2.2046 to get pounds, then divide by 14 for stones, with the remainder in pounds. For example, 72 kg is about 159 lb, which is 11 st 5 lb.