BMI Calculator Calculate Your Body Mass Index Using WHO Standards
Body Mass Index (BMI) is an internationally used measure for determining if someone is at a healthy weight. Use our calculator to check your BMI and get personalized recommendations.
Calculate Your BMI
BMI Categories
Underweight
Less than 18.5
Normal Weight
18.5 - 24.9
Overweight
25.0 - 29.9
Obese
30.0 or greater
About BMI
Body Mass Index (BMI) is a simple measure that uses your height and weight to work out if your weight is healthy. It's used by healthcare professionals to assess if someone is at risk of health problems based on their weight.
Limitations
- BMI may not be accurate for athletes or muscular individuals
- The calculation doesn't account for age, gender, or ethnicity
- It doesn't measure body fat distribution
- Pregnant women should not use BMI
Health Tips & Recommendations
Physical Activity
Aim for at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity physical activity per week.
Healthy Diet
Focus on a balanced diet rich in fruits, vegetables, whole grains, and lean proteins. Limit processed foods and sugary drinks.
Sleep & Rest
Get 7-9 hours of quality sleep per night. Good sleep habits contribute to maintaining a healthy weight.
Important Notice
This BMI calculator provides general guidelines and should not be considered as medical advice. For personalized health recommendations, please consult with a qualified healthcare professional.
Understanding Body Mass Index (BMI)
Body Mass Index (BMI) is a widely used screening tool that helps assess whether a person has a healthy body weight relative to their height. Developed in the 1830s by Belgian mathematician Adolphe Quetelet, BMI has become the standard method for preliminary assessment of weight categories that may lead to health problems.
How BMI is Calculated
BMI is calculated by dividing a person's weight in kilograms by the square of their height in meters:
BMI = Weight (kg) / [Height (m)]²
In the imperial system, the formula is slightly different:
BMI = [Weight (lbs) × 703] / [Height (inches)]²
BMI Categories According to WHO
The World Health Organization (WHO) classifies BMI into the following categories:
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obesity (Class I): BMI 30 to 34.9
- Obesity (Class II): BMI 35 to 39.9
- Obesity (Class III): BMI 40 or higher
Importance of BMI in Health Assessment
BMI serves as a useful tool for healthcare professionals to:
- Screen for weight categories that may lead to health problems
- Track weight changes in populations
- Assess the effectiveness of weight management interventions
- Identify potential weight-related health risks
Research has consistently shown that having a BMI in the overweight or obese range increases the risk of various health conditions, including:
- Cardiovascular diseases (heart disease and stroke)
- Type 2 diabetes
- Musculoskeletal disorders
- Some cancers (including endometrial, breast, ovarian, prostate, liver, gallbladder, kidney, and colon)
- Sleep apnea and respiratory problems
Limitations of BMI
While BMI is a valuable screening tool, it has several limitations:
- It doesn't distinguish between fat, muscle, and bone mass
- Athletes and muscular individuals may have a high BMI despite having healthy body fat levels
- It doesn't account for differences in body composition between different ethnicities
- It doesn't consider age or gender differences
- It doesn't measure body fat distribution (central obesity vs. peripheral fat distribution)
Due to these limitations, BMI should be used as one of several tools to assess health, rather than as the sole determinant.
Beyond BMI: Comprehensive Health Assessment
For a more comprehensive assessment of health status, healthcare professionals often consider additional measurements alongside BMI:
- Waist circumference: Measures abdominal fat, which is a risk factor for heart disease and type 2 diabetes
- Waist-to-hip ratio: Assesses body fat distribution
- Body fat percentage: Directly measures the proportion of fat in the body
- Blood pressure, cholesterol, and blood glucose levels: Indicators of metabolic health
- Physical fitness assessments: Evaluate cardiovascular fitness, strength, and flexibility
Frequently Asked Questions About BMI
According to the World Health Organization (WHO), a healthy BMI range is between 18.5 and 24.9. This range is associated with the lowest risk of weight-related health problems for most adults, regardless of gender or age. However, ideal BMI can vary slightly based on factors like ethnicity, age, and muscle mass.
BMI is not equally accurate for all individuals. It has limitations when applied to athletes, bodybuilders, pregnant women, the elderly, and certain ethnic groups. Athletes and people with muscular builds may have a high BMI despite having healthy body fat levels because muscle weighs more than fat. For these populations, other methods of assessing body composition, such as body fat percentage measurements, may be more appropriate.
For general health monitoring, calculating your BMI once or twice a year is usually sufficient. If you're actively trying to lose or gain weight, you might want to check it more frequently, perhaps every 1-3 months. However, it's important to remember that BMI is just one health indicator, and rapid changes in BMI are not always healthy. Focus on gradual, sustainable changes to your weight and lifestyle.
This calculator is designed for adults aged 18 and over. For children and teenagers (aged 2-19), a different calculation that takes into account age and gender should be used. Children's BMI is typically expressed as a percentile compared to other children of the same age and gender, rather than as an absolute number. If you're concerned about a child's weight, it's best to consult with a pediatrician who can use appropriate growth charts and assessments.
If your BMI falls outside the healthy range (18.5-24.9), it's advisable to consult with a healthcare professional. They can provide a more comprehensive assessment of your health status and determine if your weight poses any health risks. If intervention is needed, they can help you develop a personalized plan that may include dietary changes, increased physical activity, behavioral modifications, or in some cases, medical treatments. Remember that small, sustainable lifestyle changes often lead to the best long-term results.
No, BMI does not distinguish between muscle mass and fat mass. It simply measures the relationship between height and weight. This is one of its main limitations. Athletes and individuals with high muscle mass may have an elevated BMI despite having low body fat percentages. Conversely, someone with a normal BMI might have a high body fat percentage if they have little muscle mass (sometimes called "skinny fat"). For a more accurate assessment of body composition, methods like DEXA scans, bioelectrical impedance analysis, or skinfold measurements are more appropriate.