Calculate Your Body Mass Index
Use our free BMI Calculator to calculate your Body Mass Index (BMI) based on your height and weight. Enter your measurements to quickly find your BMI and see which standard BMI category your result falls into.
BMI is a simple measurement that compares your weight with your height. It is commonly used as a screening tool to help identify whether an adult’s weight falls within an underweight, normal weight, overweight, or obesity range.
Your BMI result is an estimate and does not directly measure body fat or overall health. Factors such as muscle mass, age, body composition, and other individual characteristics can affect how BMI should be interpreted.
Use the calculator above to calculate your BMI, then continue reading to learn how BMI is calculated, what the different BMI categories mean, and what the limitations of BMI are.
🛠 How to Use the BMI Calculator
Using the BMI Calculator is simple. Enter your height and weight into the calculator above to calculate your Body Mass Index (BMI).
Step 1: Enter Your Weight
Enter your current body weight using the unit selected in the calculator. Depending on the calculator settings, you can use pounds (lb) or kilograms (kg).
Step 2: Enter Your Height
Enter your height using the appropriate unit, such as feet and inches or centimeters. Make sure your height and weight are entered using the correct units to get an accurate BMI calculation.
Step 3: Calculate Your BMI
Click the calculate button to find your BMI. The calculator will use your height and weight to calculate your Body Mass Index and display your result.
Step 4: Check Your BMI Category
After calculating your BMI, compare your result with the standard adult BMI categories. These categories are used to indicate whether your BMI falls within the underweight, normal weight, overweight, or obesity range.
Your BMI result is only a screening measurement and should not be considered a diagnosis. BMI does not directly measure body fat and may not accurately represent body composition for everyone.
For more information, continue below to learn how BMI is calculated and what your BMI result means.
BMI Calculator
What Is BMI?
BMI stands for Body Mass Index. It is a measurement that uses a person's height and weight to estimate whether their body weight falls within a particular range.
BMI is commonly used for adults as a simple screening tool for assessing weight status. It can help identify whether a person's weight is classified as underweight, normal weight, overweight, or obesity according to standard BMI categories.
BMI does not directly measure body fat. Instead, it compares weight with height using a mathematical formula. This makes BMI useful for quickly assessing weight at a population or individual level, but it also means that the result does not provide a complete picture of a person's health or body composition.
What Does BMI Measure?
BMI measures the relationship between your body weight and height.
For example, two people can have the same weight but different BMI values if they have different heights. A taller person will generally have a lower BMI than a shorter person at the same body weight.
BMI can therefore be useful for putting a person's weight into a standardized range based on their height.
Why Is BMI Used?
BMI is widely used because it is simple to calculate, inexpensive, and does not require specialized equipment. Healthcare professionals and researchers commonly use BMI as one measurement when assessing weight and health.
However, BMI should be considered alongside other factors rather than used on its own. Body composition, muscle mass, age, and other individual characteristics can affect how a BMI result should be interpreted.
Use the BMI Calculator above to calculate your BMI, then continue below to learn how the BMI formula works and how your result is classified.
⚖️ How Is BMI Calculated?
BMI is calculated by comparing your body weight with your height. The formula used depends on whether you are using metric or imperial measurements.
BMI Formula
When using kilograms and meters, the BMI formula is:
BMI = weight in kilograms ÷ height in meters²
For example, if you weigh 70 kg and are 1.75 meters tall:
BMI = 70 ÷ (1.75 × 1.75)
BMI = 22.9
This gives a BMI of approximately 22.9.
How to Calculate BMI Using Pounds and Inches
If you use pounds and inches, the BMI formula is:
BMI = (weight in pounds ÷ height in inches²) × 703
For example, if you weigh 154 pounds and are 69 inches tall:
BMI = (154 ÷ (69 × 69)) × 703
BMI = 22.7
This gives a BMI of approximately 22.7.
Why Is Height Squared in the BMI Formula?
Height is squared in the BMI formula because BMI is designed to relate body weight to height in a standardized way. The formula allows people with different heights to be compared using the same measurement.
You do not need to calculate the formula manually when using our BMI Calculator. Simply enter your height and weight, and the calculator performs the calculation for you.
The BMI formula provides a numerical result that can then be compared with standard adult BMI categories. Continue below to learn what the different BMI ranges mean.
Understanding BMI Categories
For adults, BMI results are commonly divided into four standard categories. These categories provide a general indication of whether a person's weight falls below, within, or above the standard healthy-weight range for their height.
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5–24.9 | Normal weight |
| 25.0–29.9 | Overweight |
| 30.0 or higher | Obesity |
These BMI categories are intended for adults and are used as a general screening tool. A BMI result should not be interpreted as a diagnosis or as a complete assessment of your health.
Underweight: BMI Below 18.5
A BMI below 18.5 is classified as underweight. A low BMI can have different causes, including naturally low body weight, insufficient nutrition, illness, or other factors.
If you are concerned about being underweight or have experienced unexplained weight loss, consider discussing your situation with a healthcare professional.
Normal Weight: BMI 18.5–24.9
A BMI between 18.5 and 24.9 is classified as normal weight according to standard adult BMI categories.
Being within this range does not necessarily mean that a person is healthy in every respect. BMI does not measure body fat, muscle mass, fitness, or other aspects of health.
Overweight: BMI 25.0–29.9
A BMI between 25.0 and 29.9 is classified as overweight.
A BMI in this range may indicate that a person's body weight is higher than the standard reference range for their height. However, BMI does not distinguish between muscle and fat, so the result should be interpreted alongside other factors.
Obesity: BMI 30.0 or Higher
A BMI of 30 or higher is classified as obesity according to standard adult BMI categories.
Higher BMI values can be associated with an increased risk of certain health conditions, but BMI alone cannot determine an individual's health or medical risk.
What Is a Healthy BMI?
For adults, a BMI between 18.5 and 24.9 is generally considered to be within the standard healthy-weight range.
However, a healthy weight cannot be determined by BMI alone. Factors such as age, muscle mass, body composition, lifestyle, and overall health should also be considered.
Use the BMI Calculator above to calculate your BMI and see which standard category your result falls into.
🔄 What Does Your BMI Result Mean?
Your BMI result gives you a number that can be compared with standard adult BMI categories. It provides a general indication of how your weight relates to your height, but it should not be considered a complete measure of your health.
For example, a BMI of 22 falls within the standard normal-weight range, while a BMI of 27 falls within the overweight range. A BMI of 32 falls within the obesity range.
What Does a BMI of 20 Mean?
A BMI of 20 is within the standard normal-weight range for adults. It indicates that your weight falls within the reference range for your height according to standard BMI categories.
What Does a BMI of 25 Mean?
A BMI of 25 is at the beginning of the standard overweight category. It is just above the normal-weight range of 18.5–24.9.
A BMI of 25 does not by itself mean that you are unhealthy. BMI does not distinguish between muscle mass and body fat, so other factors should also be considered.
What Does a BMI of 30 Mean?
A BMI of 30 is at the beginning of the standard obesity category for adults.
A BMI of 30 or higher can be associated with an increased risk of certain health conditions, but BMI alone cannot determine an individual's health or medical risk.
What If My BMI Is Outside the Normal Range?
Having a BMI below or above the standard normal-weight range does not automatically mean that you have a health problem. BMI is a screening measurement and should be considered together with other information about your health and body composition.
For example, people with a high amount of muscle mass can have a higher BMI because muscle weighs more than the same volume of body fat. BMI may therefore be less useful for assessing body composition in some individuals.
If you are concerned about your BMI, weight, or overall health, consider discussing your result with a qualified healthcare professional.
Use the BMI Calculator above to calculate your BMI and compare your result with the standard adult BMI categories.
📊 What Are the Limitations of BMI?
BMI is a useful and simple screening measurement, but it does not provide a complete picture of a person's health or body composition. BMI only uses height and weight, so it cannot distinguish between different types of body tissue or account for every factor that affects health.
BMI Does Not Measure Body Fat Directly
BMI does not directly measure how much body fat you have or where that fat is stored. Two people with the same BMI can have very different body compositions.
For example, a person with a high amount of muscle mass may have a higher BMI because muscle contributes to body weight. This means that BMI can sometimes classify muscular people as overweight or obese even when they have relatively little body fat.
BMI Does Not Measure Muscle Mass
Because BMI is based only on height and weight, it cannot determine how much of your body weight comes from muscle, fat, bone, or other tissues.
This is particularly important for athletes and people who have developed significant muscle mass through strength training or other physical activities.
BMI Can Vary With Age and Other Factors
BMI is interpreted differently for children and teenagers than it is for adults because body composition changes as people grow. The standard adult BMI categories on this page are intended for adults.
Other factors, including age, sex, ethnicity, body composition, and where body fat is stored, can also affect how a BMI result should be interpreted.
BMI Is a Screening Tool, Not a Diagnosis
A BMI result should be viewed as one piece of information rather than a diagnosis of health or disease.
A person's overall health can depend on many factors, including blood pressure, physical activity, nutrition, medical history, body composition, and other measurements that are not included in a BMI calculation.
For this reason, a BMI Calculator is best used as a general screening and reference tool. If you have concerns about your weight or health, a qualified healthcare professional can help you interpret your BMI in the context of your individual circumstances.
🚀 BMI and Healthy Weight
BMI can be used to estimate a general weight range associated with the standard adult BMI range of 18.5 to 24.9. Because BMI is based on height and weight, the corresponding weight range is different for every height.
For example, a person who is 5 feet 9 inches (175 cm) tall has a different BMI-based weight range than someone who is 6 feet 2 inches (188 cm) tall.
How Is a Healthy Weight Range Calculated From BMI?
To estimate a BMI-based weight range, you can use the BMI formula in reverse.
For metric measurements:
Weight = BMI × height²
Using a BMI range of 18.5 to 24.9, you can calculate the approximate lower and upper weights associated with that range for a particular height.
For example, for a height of 1.75 meters:
Lower weight = 18.5 × 1.75² ≈ 56.7 kg
Upper weight = 24.9 × 1.75² ≈ 76.3 kg
This gives an approximate BMI-based weight range of 56.7–76.3 kg for a height of 1.75 meters.
BMI-Based Weight Range by Height
| Height | Approximate BMI 18.5–24.9 Weight Range |
|---|---|
| 5'0" (152 cm) | 43–58 kg |
| 5'2" (157 cm) | 46–61 kg |
| 5'4" (163 cm) | 49–66 kg |
| 5'6" (168 cm) | 52–70 kg |
| 5'8" (173 cm) | 55–75 kg |
| 5'10" (178 cm) | 59–79 kg |
| 6'0" (183 cm) | 62–83 kg |
| 6'2" (188 cm) | 65–88 kg |
| 6'4" (193 cm) | 69–93 kg |
These values are approximate and are based only on the standard adult BMI range of 18.5–24.9. They should not be interpreted as a universal ideal weight or as a medical recommendation.
A healthy weight can vary considerably between individuals because BMI does not account for muscle mass, body composition, or other factors that can affect health.
Use the BMI Calculator above to calculate your BMI based on your own height and weight.
BMI Reference and Examples
BMI is expressed as a number rather than a percentage. The number can then be compared with the standard adult BMI categories.
The examples below show how different BMI values are generally classified:
| BMI | Standard Adult Category |
|---|---|
| 17 | Underweight |
| 18.5 | Normal weight |
| 20 | Normal weight |
| 22 | Normal weight |
| 24.9 | Normal weight |
| 25 | Overweight |
| 27 | Overweight |
| 29.9 | Overweight |
| 30 | Obesity |
| 35 | Obesity |
| 40 | Obesity |
Example: BMI of 20
A BMI of 20 falls within the standard normal-weight range of 18.5–24.9 for adults.
Example: BMI of 25
A BMI of 25 is at the beginning of the standard overweight category. It is just above the normal-weight range.
Example: BMI of 30
A BMI of 30 is at the beginning of the standard obesity category.
Example: BMI of 35
A BMI of 35 falls within the obesity category. Higher BMI values can be associated with increased health risks, although BMI alone cannot determine an individual's overall health.
Example: BMI of 40
A BMI of 40 is also within the obesity category and represents a substantially higher BMI than the standard reference range.
These examples are intended to help explain BMI values and their standard classifications. A BMI number should always be interpreted in context because BMI does not directly measure body fat, muscle mass, or overall health.
For a personalized result, enter your height and weight into the BMI Calculator above.
Frequently Asked Questions About BMI
What is BMI?
BMI stands for Body Mass Index. It is a measurement calculated using a person's height and weight. BMI is commonly used as a screening tool to classify adult weight into categories such as underweight, normal weight, overweight, and obesity.
How do I calculate my BMI?
For metric measurements, BMI is calculated by dividing your weight in kilograms by your height in meters squared.
BMI = weight (kg) ÷ height (m)²
You can use the BMI Calculator above to calculate your BMI automatically by entering your height and weight.
What is a normal BMI?
For adults, a BMI between 18.5 and 24.9 is generally classified as normal weight according to standard BMI categories.
However, BMI is only a screening measurement and does not provide a complete assessment of health or body composition.
Is a BMI of 25 considered overweight?
Yes. A BMI of 25.0–29.9 is generally classified as overweight for adults. A BMI of 25 is therefore at the beginning of the standard overweight category.
Is a BMI of 30 considered obese?
Yes. A BMI of 30 or higher is generally classified as obesity for adults. However, BMI should not be used by itself to determine an individual's health or medical condition.
Does BMI measure body fat?
No. BMI does not directly measure body fat. It is calculated from height and weight and cannot distinguish between fat, muscle, bone, or other components of body weight.
This means that people with a high amount of muscle mass can sometimes have a high BMI without having a high level of body fat.
What is a healthy BMI for adults?
A BMI between 18.5 and 24.9 is generally considered to be within the standard healthy-weight range for adults.
However, there is no single BMI value that determines whether a person is healthy. Age, body composition, lifestyle, medical history, and other factors should also be considered.
Is BMI the same for men and women?
The standard adult BMI categories are generally the same for men and women. However, BMI does not account for differences in body composition between individuals, including differences in muscle mass and body-fat distribution.
Can a muscular person have a high BMI?
Yes. BMI is based only on height and weight and does not distinguish between muscle and fat.
Someone with a high amount of muscle mass may therefore have a BMI in the overweight or obesity category even though they have relatively little body fat.
Is BMI accurate?
BMI can be useful as a general screening measurement, but it is not a precise measure of body fat or overall health. Factors such as muscle mass, body composition, age, and other individual characteristics can affect how a BMI result should be interpreted.
For this reason, BMI should be considered alongside other relevant health information rather than used as a diagnosis.
Related Calculators and Tools
If you are using the BMI Calculator to track your health, weight, or activity, these related calculators may also be useful.
Health and Fitness Calculators
- Body Fat Calculator — Estimate your body fat percentage using measurements such as height, weight, neck, and waist.
- Age Calculator — Calculate your exact age and the time between two dates.
- Steps to Calories Calculator — Estimate how many calories you may burn from walking and taking daily steps.
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These calculators can be used alongside the BMI Calculator to get a broader view of measurements related to health, fitness, and everyday calculations.
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