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What Should Your BMI Be? Using A Body Mass Calculator

A body mass calculator is only a rough guide to your ideal weight. It’s far from perfect. Often athletes with big muscles will be classed as overweight based purely on their Body Mass Index (BMI). So what should your BMI be?

I read a story recently about someone with atypical anorexia who was told they were overweight based on their BMI (and that was by a doctor). Your body fat percentage is a much better indicator.

Know its limitations and don’t beat yourself up about the result. At best a body mass calculator is a rough indicator of whether you’re underweight, normal, overweight, or obese. Medical advice is to aim to be within the normal range*.

BMI body mass calculator
Use your BMI as a guide only

The best ways to be healthy are:

  • healthy eating – eating your 5-a-day fruit and vegetables, reducing high-sugar, high-fat foods, and eating more whole grains. Choose healthier protein sources – beans, peas, lentils, tofu, nuts, and seeds. Plant-based foods are very low in saturated fat and cholesterol-free.
  • fitness – exercising regularly,
  • consuming alcohol in moderation.
  • quit smoking.

Check your BMI using this calculator BUT remember it’s only an indicator

BMI Calculator


Unit of measurement *



Underweight< 18.5
Normal18.5 – 24.99
Overweight25 – 29.99
Obese> 30


Being underweight can lead to serious health issues. It can mean your body is failing to get the nutrients you need.

Often the underlying causes of being underweight are eating disorders, depression, or stress. It’s time to get help. Make a doctor’s appointment or call a helpline. UK helpline. US helpline.


Woo-hoo! Your BMI is in the normal range. Keep up the good work just make sure you eat healthy foods and exercise regularly.

A normal BMI isn’t a guarantee of good health but it does mean there’s less risk of weight-related conditions such as type 2 diabetes, heart disease, and high blood pressure. Any concerns – check in with your doctor.


If your BMI falls into the overweight range, you could be at greater risk of weight-related conditions. The main risks are type 2 diabetes, heart disease, and high blood pressure.

If you’re an athlete who eats healthy food and exercises regularly, it’s highly possible your BMI in the overweight range is caused by the weight of your muscles.

Your BMI is also a poor indicator of overall health even if you’re… well just a bit fat. (Is it okay to use the fat word these days? Well, I’ve gone and said it now).

Eating your fruit and veg, exercising, limiting your alcohol intake, and quitting smoking, are the best ways to stay healthy.

An extra indicator is your waist measurement, (although again athletes have stronger core muscles and can have bigger waist measurements). Yet again this is just a guide.

Generally, men with a waist size of 94cm (37 inches) or more and women with a waist size of 80cm (31.5 inches) or more are more likely to develop obesity-related health problems.


An overweight BMI can mean your need to make some lifestyle changes. Eliminate junk food from your diet, reduce or quit sugar and fill up with fresh fruit and vegetables. Make exercise part of your daily life. Check-in with your doctor for advice on how to lose weight.


If your BMI falls into the obese range you’re at high risk for heart disease, stroke, type 2 diabetes, high blood pressure, and some cancers. It’s time to check in with your doctor and make some big changes to your lifestyle.

Seek out medical advice on how to improve your diet and safely exercise. Healthy eating and regular exercise are key to improving your health. It’s time to take action!

Frequently Asked Questions

What should my BMI be for my age?

According to the NHS, a normal BMI for an adult is between 18.5 – 24.99. Less than this is considered underweight and more than this is overweight. A BMI of over 30 is considered obese.

What is the best BMI?

Your ideal BMI is between 18.5 – 24.99 if you’re an adult. BMI is an indicator, not a hard and fast rule. Athletes with large muscle mass can be outside this range.

How can I drop 10 pounds in a week?

Losing 10 pounds in a week is never advisable. Crash diets rarely work and most people regain all the weight they lose rapidly as soon as they stop dieting. It’s better to adopt sustainable healthy eating habits and aim to lose 1-2 lb a week.