You should speak to your doctor to find out why you have a low BMI and about how to gain weight healthily. Women may have irregular periods and have a greater chance of osteoporosis. It may affect your skin, hair, and teeth or you may feel more tired than you should. What your BMI score means Underweightīeing underweight might mean you're not getting all the nutrients, vitamins, and minerals that your body needs to be healthy. But rather than working it out yourself you can use the BMI calculator above to find out which range you're in. You can also do this in imperial measurements. So, your BMI is 23, which falls within the healthy weight range.Your BMI is calculated by dividing your weight by your height squared.įor example, if you're 1.75m metres tall and weigh 70 kilograms, the calculation to get your BMI is: If you think you have an eating disorder, the BMI calculator may not be suitable for you. This calculator should only be used by adults. Pregnant or lactating women should not rely on these BMI results, and no action should be taken based on its values other than to consult a qualified person such as a doctor.