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How to work out your BMI.

When assessing whether to offer you a life insurance policy and deciding which terms you will be offered, insurers take into account many different aspects of your day-to-day life. This can include what you do in your spare time, what kind of job you have and your overall health – both mental and physical.

A set of bathroom scales and a measuring tape on a pink background.

Typically, you will be asked about medical conditions you may have had in recent years, but you’ll also be asked to give certain measurements so that insurers can assess your body mass index (BMI). This figure can determine your likelihood of developing certain conditions that tend to affect overweight people more than others. If you’re more likely to develop a serious condition, you could be more likely to make a claim, meaning you represent a higher risk to insurers.

While BMI of course isn’t the only thing insurers use to inform their decision, it is one you can get a good idea about before even applying for an insurance policy. You can do this by learning to measure your own BMI and understanding what it means for your application and for your overall health.

How to measure BMI.

Fortunately, measuring your BMI is simple – anyone can do it with the right equipment at home, which most of us are likely to have. All you will need is a way to measure your height, such as a tape measure, and a way to determine your weight, such as a set of bathroom scales. We also recommend using a calculator of some description to ensure the accuracy of your calculations.

To get started, take off any shoes or slippers you might be wearing and stand flat on the ground. Measure your height as accurately as possible – it can be helpful to ask a loved one to help you with this. If you’re using feet and inches, convert your height into metres and write this figure down so you don’t forget it. 

Next, it’s time to measure your weight. Ideally, you don’t want to skew your measurements by wearing heavy garments, so take off anything that might impact your overall weight, including shoes. Some people like to measure their weight in their underwear for the most accurate readings. Take your measurements in kilograms, or make sure to convert from pounds or stone. Again, it’s a good idea to write your resultant figure down. 

Once that’s done, the physical aspect of measuring your BMI is completed. Now you need to do a bit of maths to get your BMI figure. You’ll need to:

  1. Square your height in metres (multiply the figure by itself).
  2. Divide your weight in kilograms by your answer to step 1. 

So, if you were 1.75 metres tall and weighed 90kg, it would look like this: 

1.75 x 1.75 = 3.06

90 / 3.06 = 29.4

Therefore, your BMI would be 29.4. If you’d prefer not to do the maths yourself, then there are plenty of calculators available online that will do it for you. We recommend sticking to the NHS BMI calculator for a reputable result, as this page also contains helpful information about what to do once you’ve calculated your BMI.

What is a healthy BMI?

It’s important to remember that BMI is only an approximate indicator of health, and it can be flawed. BMI only takes into account your height and weight, not how much fat you have. Therefore, if you have a lot of muscle but a low body fat percentage, BMI might class you as overweight or obese when in fact you’re a healthy weight. This is why insurers use other measures of health as well to help get a clearer picture of your overall health. If this is your situation, measuring your waist-to-height ratio may provide more context. 

The general weight brackets used to classify your BMI score are as follows:

  • Below 18.5 – underweight
  • 18.5 to 24.9 – healthy weight
  • 25 to 29.9 – overweight
  • 30 to 39.9 – obese
  • 40 or higher – severely obese.

However, if your family background is Asian, Chinese, Middle Eastern, Black African or African-Caribbean, you should consider using lower brackets to check if you’re classed as overweight or obese. These are:

  • 23 to 27.4 – overweight
  • 27.5 or higher – obese.


This is because people of these ethnicities can have a higher likelihood of developing obesity-related problems at a lower BMI. Taking this into account helps to give you a better picture of your health. 

As we’ve mentioned, BMI provides little more than a snapshot of a single aspect of your overall health. Whatever your result, you shouldn’t consider it a diagnosis of any kind. If you’re at all concerned about your BMI, no matter where on the scale you sit, you should speak to your GP about your health to learn more about your specific circumstances.

Furthermore, having a high BMI doesn’t necessarily mean you can’t get life insurance. With the help of specialist brokers like the Insurance Surgery team, high BMI life insurance is accessible and as affordable as possible, making it easier for you to fulfil your financial goals no matter what.