BMI, or Body Mass Index, is a measure health experts use to determine if a person is a healthy weight for their height.
Wondering whether you’re a healthy weight? Rather than just going by what the scales say, our BMI calculator takes your height and weight into consideration to determine if you are either “underweight”, “healthy”, “overweight”, “obese” or “extremely obese”.
While the measure doesn’t directly measure body fat, it can provide an indicator as to whether you’re carrying excess weight, according to your height.
Widely used by healthcare professionals, Body Mass Index is calculated using your weight in kilograms divided by your height in metres squared. For example, a BMI of 24 is 24kg per metre squared.
Many people use the BMI calculation to determine if they are the right weight for their height or if they need to lose weight before embarking on a health plan.
How to use our BMI calculator
To work out your BMI, all you need to do is find your weight along the top and your height along the left-hand side of our BMI chart. Once you’ve found those, check to see where the two numbers meet in the middle. This is your Body Mass Index. If you’re not sure what you weigh in kilos and pounds, you can use our handy kilos to stones converter.
Our Body Mass Index chart
What does my BMI result mean?
Once you’ve worked out your BMI, you’ll end up with a number that will tell you which category of weight you fall into.
If your BMI number is…
Under 18.5: Underweight
Between 18.5-25: Healthy weight
Between 25-30: Overweight
Between 30-40: Obese
Over 40: Extremely obese
Does the BMI calculator work for everyone?
The BMI calculation won’t work for pregnant women, women who are breastfeeding, or for kids. It also won’t be accurate for athletes, people who weight-train, if you’re over 60 or if you have a long-term health condition, so it’s important to take these factors into consideration when calculating your BMI.
What shall I do if my result is anything other than “healthy weight”?
Whether your BMI calculator results come back showing you are underweight or overweight, it’s important to remember that this is a guide. The BMI calculations can’t tell the difference between fat, muscle and bone, so if you’re worried it’s important to speak to your doctor. Being underweight or overweight can lead to many health problems, so consult a health professional if you have any concerns.
Ideal weight for men
The ideal weight for a man will very much depend on their height and their build. What is a healthy weight for someone that’s 5’8 will not necessarily be a good weight for someone who is 6’5.
At the time of the last census in the UK, the average British man was 5’7.5 tall and weighed 83.6kg. On a BMI calculator, this would suggest that the average man is overweight. Using this method, they should weigh between 56.8 and 72.7kg. However the calculator doesn’t take into account muscle mass, whether you have a long-term health condition or if you’re over 60.
Another way to work out ideal body weight in relation to height for a man is to follow the formula, 50 kg + 2.3kg for each inch over 5 feet.
Ideal weight for women
Much the same as with men, a woman’s ideal weight depends entirely on their height and lifestyle. Such as, whether they weight train, are pregnant, breastfeeding, have a long term health condition or are over 60.
At the last census, the average woman 5’3 tall and weighs 70.2kg. This is a healthy weight on the BMI calculator, so if this matches your description then you’re at a close to ideal weight for your height and body type.
However, you can also work out your ideal weight in relation to your height using the a similar formula to the men, 45.5 kg + 2.3 kg for each inch over 5 feet.
How to lower BMI
A balanced diet and plenty of exercise are key to lowering your BMI and maintaining a healthy weight. Rather than fad diets that promote rapid weight loss, it’s important to be realistic with dietary changes so you can keep them up in your daily routine.
Some ways to make effective changes include swapping your regular 3pm sweet treat for something healthier like an apple or hummus with crudités – yum!
Keeping active is also essential to lowering your BMI. Find more ways to move during the day, like taking the stairs instead of the lift, or trying one of these 15 minute workouts. But being realistic and consistent is important – pounding away at the gym for four hours once a month isn’t going to make as much of a difference as doing short bursts of activity every day.
How to increase BMI
Being underweight is associated with all sorts of health issues, including weak bones, fatigue and anaemia.
The NHS recommends eating enough calories for your height through a varied and balanced diet. This includes getting your five-a-day and eating meals based on wholegrain like sweet potatoes, wholemeal bread and pasta.
The aim is to increase your weight gradually, so avoid piling on processed, high-calorie food like cake and chocolate in an attempt to gain weight quickly. Instead opt for energy-rich foods such as full fat milk, peanut butter and avocados that help you build muscle instead of fat.
Protein is also important to building lean muscle mass and increasing your BMI. Eggs, pulses and fish are all good choices, so try oily fish like mackerel or salmon recipes.
You can also boost muscle with regular strength-training exercises, like those found in our 30-day HIIT challenge.
Consult your GP before embarking on a new exercise regime.