How much should I weigh?

What is a ‘healthy’ weight?

The most common way of assessing whether you’re a healthy weight is to calculate your body mass index (BMI). This is a measure that uses your height and weight to evaluate whether your weight falls within a ‘healthy’ range. The figure for an adult is calculated by dividing weight in kilograms by height in metres squared. You can calculate your BMI here.

For most adults, an ideal range is considered to be a BMI between 18.5-24.9. Age doesn’t factor in the BMI calculation for adults, but it does for children.

What does my BMI mean?

If your BMI score is:

• Below 18.5: you're in the underweight range
• Between 18.5-24.9: you're in the healthy weight range
• Between 25-29.9: you're in the overweight range
• 30 or over: you're in the obese range

What is the downside of the BMI calculation?

BMI as a tool has been in existence for almost two centuries, originally developed to assess how 'at risk' an individual was of premature illness or death. It became used as an international measure for obesity assessment in the 1980s.

However, science has moved on since the BMI was first developed, and we now know that it's not just body weight that is a risk factor when it comes to longevity. How weight is carried and in which tissues it is stored is also important, and not taken into account by the BMI score.

For example, muscle is much denser than fat, so very muscular people, such as body builders, rugby players and some athletes, may be a healthy weight even though their BMI falls within the ‘obese’ range. The BMI calculation also can’t distinguish between excess fat or bone mass, nor does it provide an indication of the proportion or distribution of body fat.

Add to this that the existing BMI definitions are based largely on white populations, although body composition, including body fat or amount of muscle mass, may vary by ethnic group, means using BMI as a predictor of health may be less accurate for non-white groups.

What does BRI (body roundness index) mean?

In order to get around many of these issues, the body roundness index (BRI) was designed as an alternative to BMI. It takes into account height and waist circumference. The BRI generates a score of one to 20, where one represents narrow and 20 more round body types. The value of the BRI is that it helps to more accurately determine the actual body fat levels of people with the same BMI but who have different heights and waist circumferences. The BRI also takes into account your age, gender, height, race as well as your weight.

To calculate your own score, check out the BRI calculator.

What other alternatives are there to BMI?

A simple waist-to-height measurement can be a useful way to assess your fat distribution. Even if your BMI is in the moderate range, if more of your weight is carried in this mid-section, you may be at higher risk of heart disease or diabetes. Find out how to calculate your waist to height ratio.

There are a number of other ways to measure body composition, but most rely on more complex technologies, making them less accessible. Skinfold thickness, bioelectrical impedance, underwater weighing and dual energy x-ray absorption (DEXA) are examples, and are thought to be more accurate. This is because they provide a picture of total body composition, including fat, bone, lean tissue and water. However, many of these methods are expensive, intrusive or simply not available to the majority of us.

Is BMI a useful measure?

BMI may be useful for some people but is not appropriate for everyone. This is because the resulting figure can be distorted by pregnancy and high muscle mass, and it may be unreliable as a measure for children or the elderly. If you are pregnant and want to understand if your weight gain is healthy, seek advice from your GP or midwife.

For children and young people (aged two to 18 years), the BMI calculation takes account of age and gender, as well as height and weight.

Despite its failings, BMI may be a useful starting point, but you need to recognise that other factors, such as fat distribution, genetics, age and fitness level all contribute to your overall health status.

So how much should I weigh?

The answer to this is ‘it depends’ – this is because we are all unique and the body weight we carry will be influenced by our ethnicity, gender, age and frame as well as environmental influences and lifestyle choices.

It’s worth remembering that weight alone is not the only determinant of health, and many other factors, including eating a balanced diet, getting adequate sleep and exercise, as well as measures such as your blood pressure, cholesterol and blood sugar levels, liver and kidney function and red and white blood cell counts also contribute to your overall health picture.

Although BMI may be a useful starting point it doesn’t take account of your race, age, gender, genetics, amount of body fat versus muscle mass or your lifestyle so it may be necessary to consider other alternative measures to assess your health and weight.

Now read:

How to lose weight healthily
How to lose body fat
Am I overweight? How to check your weight is healthy
How many calories to lose weight?
What is a calorie deficit?
Healthy recipes for weight loss

This page was reviewed on 14 April 2025 by Kerry Torrens

All health content on goodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.