BMI Calculator
What is BMI?
BMI, which stands for Body Mass Index, is a numerical measurement derived from a person’s height and weight, used to gauge body fat levels.
It categorizes individuals into underweight, normal weight, overweight, or obese categories, making it an essential tool in health assessments. Health professionals globally rely on BMI to evaluate weight-to-height ratios accurately.
Keep in mind that BMI is not a perfect model, and there are situations where it should not be applied.
Some examples of situations where BMI should not be applied are as follows:
- Children younger than the age of 18.
- People with developmental issues.
- People with disabilities.
- People with various diagnoses that can affect their body weight.
Importance of BMI
BMI is very important when it comes to understanding your body composition and potential health risks associated with excess weight or low body weight. It helps healthcare professionals and individuals get an idea about their current health and take appropriate action based on the results.
When interpreting the results of your BMI, you should always refer to the BMI scale, which gives you an idea of your overall health. Keep in mind that before you take any radical action based on your BMI results, such as dieting, medication, or deciding to take on more exercise, you should always consult these upcoming changes with a healthcare professional.
The BMI scale
The result from our BMI calculator can then be interpreted by using the following BMI scale:
| BMI | Classification |
| less than 18.5 | underweight |
| 18.5 – 24.9 | normal weight |
| 25 – 29.9 | overweight |
| 30 – 34.9 | class I obese |
| 35 – 39.9 | class II obese |
| 40 upwards | class III obese |
Interpretations for each category
Unless advised otherwise by a healthcare professional, the usual course of action to mitigate any potential risks associated with each category is as follows:
| Category | Potential Risks | Course of Action |
|---|---|---|
| Underweight (BMI less than 18.5) | Nutrient deficiencies, weakened immune system. | Increase calorie intake with nutrient-dense foods. Regularly consult with a dietitian or healthcare provider for personalized advice and monitoring. Take dietary supplements based on bloodwork results and professional recommendations. |
| Normal Weight (BMI 18.5 – 24.9) | Generally lower health risks compared to other BMI categories. This is considered the ideal range for most people. | Maintain a balanced diet comprising fruits, vegetables, lean proteins, and whole grains. Engage in regular physical activity and monitor weight and health annually. Unless advised by a healthcare professional, there might be no need for any action. |
| Overweight (BMI 25.0 – 29.9) | Increased risk of cardiovascular disease, and type 2 diabetes. | Adopt healthy eating habits, such as reducing calorie intake and choosing nutritious foods. Increase physical activity levels, regularly monitor health markers, and consider professional support for weight management. |
| Class I Obese (BMI 30.0 – 34.9) | Higher risk of hypertension, and sleep apnea. | Start a structured weight loss program under medical supervision. Focus on lifestyle changes including diet modifications and increased physical activity. Regularly monitor blood pressure and sleep quality. |
| Class II Obese (BMI 35.0 – 39.9) | Increased risk of heart disease, and stroke. | Work closely with healthcare providers to develop a comprehensive weight management plan. Follow medical advice closely. |
| Class III Obese (BMI 40.0 and above) | Severe risk of cardiovascular disease, and joint problems. | Seek immediate medical advice and intervention. Consider weight loss surgery under medical supervision if appropriate. Follow medical advice closely. |
Using the BMI Calculator.
| Step | |
|---|---|
| 1 | Select Your Gender: Choose between Male or Female. |
| 2 | Choose Measurement Units: |
| 2a | Weight: Decide between Pounds (LB) or Kilograms (KG). |
| 2b | Height: Choose Centimeters (CM) or Feet (FEET). |
| 3 | Enter Your Details: Input your weight and height based on your selected units. |
| 4 | Calculate Your BMI: Click on the CALCULATE button to obtain your BMI score. |
Calculation Method
BMI is calculated using the formula:
BMI = \tfrac{(Weight~KG)}{(Height~M)^2}NOTE: If you are using imperial units manually, you must first convert them to metric. Our calculator does this automatically for you!
Example Calculation
Let’s calculate BMI for Sarah, a female who weighs 65 kilograms and is 170 centimeters tall:
| Step | Instructions |
| 1 | We convert her height into meters as 170 cm = 1.7 meters |
| 2 | We plug into our formula WEIGHT = 65, HEIGHT = 1.7 |
| 3 | We count 65÷1.72 = 65÷2.89 = 22.5, rounded to 1 decimal place |
| 4 | We interpret this weight using the BMI scale as normal weight |