BMI Calculator For Men & Women
Calculate your Body Mass Index and learn more about your health
Body Mass Index (BMI) is a screening measure calculated from your weight relative to your height. It can help categorize weight status in adults, but it does not directly measure body fat or diagnose health conditions.
BMI Categories:
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25 to 29.9
- Obese: BMI 30 or greater
Limitations: BMI doesn't account for muscle mass, bone density, overall body composition, and racial and sex differences. For example, athletes might have a high BMI due to increased muscle mass rather than increased body fat.
Waist-to-Height Ratio is a simple screening tool that can indicate central obesity. For adults with a BMI below 35, waist-to-height ratio can be used alongside BMI as a practical estimate of central adiposity. NICE advises adults to aim to keep their waist circumference at less than half their height, corresponding to a waist-to-height ratio below 0.5.
- 0.40–0.49: Healthy central adiposity
- 0.50–0.59: Increased central adiposity
- 0.60 or above: High central adiposity
This calculator provides general information only. It is not a substitute for professional medical advice. Please consult a healthcare provider for personalized health guidance.
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How to calculate bmi complete guide?
What Is BMI?
BMI, or Body Mass Index, is a calculation that compares your weight with your height. It provides a quick and inexpensive way to screen weight status in adults.
BMI is widely used because it requires only two basic measurements: height and weight. Once these measurements are entered into a BMI calculator, the result can be compared with standard adult BMI categories. However, BMI does not directly measure body fat. Two people can have the same BMI while having very different amounts of muscle and body fat. This is why BMI should be interpreted alongside other relevant health information.
What is a BMI Calculator?
A BMI Calculator is a simple tool that estimates whether your weight is healthy for your height. It uses the internationally recognized Body Mass Index (BMI) formula to calculate your BMI score in seconds. The result helps identify whether you are underweight, at a healthy weight, overweight, or living with obesity. While BMI is a useful screening tool, it does not directly measure body fat or overall health. Use our BMI Calculator for a quick and free assessment to better understand your weight status.
How to Calculate BMI?
The Body Mass Index is a quick and simple screening tool that relates your weight to your height. While it has limitations and doesn’t measure body fat directly, it’s often used by healthcare professionals to broadly categorize a person’s weight and potential health risks.
You can calculate BMI using either the Metric System or the Imperial System (US Units).
Metric BMI Formula
The metric formula is the standard way to calculate BMI:
Steps:
- Measure your weight in kilograms (kg).
- Measure your height in meters (m). If you know it in centimeters (cm), divide the centimeters by 100 to convert to meters (e.g. 175 cm / 100 = 1.75 m).
- Square your height in meters (multiply the height by itself).
- Divide your weight (kg) by your squared height (m2).
Example:
- Weight: 75 kg
- Height: 1.75 m
US Imperial BMI Formula
If you use pounds and inches, you’ll need a conversion factor (703) in the calculation:
Steps:
- Measure your weight in pounds (lb).
- Measure your height in inches (in). (Remember, 1 foot = 12 inches).
- Square your height in inches (multiply the height by itself).
- Divide your weight (lb) by your squared height (in2).
- Multiply that result by the conversion factor, 703.
Example:
- Weight: 150 lb
- Height: 5’5″ (which is 5 X 12 + 5 = 65 inches)
What Is a Healthy BMI?
For most adults, a BMI between 18.5 and 24.9 falls within the standard healthy-weight category.
A BMI below 18.5 is classified as underweight, while a BMI from 25.0 to 29.9 falls within the overweight category. A BMI of 30.0 or higher falls within the obesity category.
These ranges are useful for screening, but your BMI category alone cannot determine whether you are healthy or unhealthy.
A healthcare professional may consider your BMI together with factors such as your:
- Waist measurement
- Blood pressure
- Cholesterol levels
- Blood glucose
- Medical history
- Physical activity
- Diet
- Body composition
- Other clinical findings
Your BMI is therefore best viewed as a starting point rather than a complete assessment of your health.
BMI Chart for Adults
The following BMI chart provides a more detailed breakdown of adult BMI categories.
| BMI Range | Classification |
| Below 18.5 | Underweight |
| 18.5–24.9 | Healthy weight |
| 25.0–29.9 | Overweight |
| 30.0–34.9 | Obesity Class 1 |
| 35.0–39.9 | Obesity Class 2 |
| 40.0 or above | Obesity Class 3 |
If your BMI falls outside the healthy-weight range, it does not automatically mean you have a health problem. Consider discussing your result with a qualified healthcare professional, particularly if you have other health concerns or have experienced an unexpected change in weight.
Body Mass Index (BMI) Table for Adults
Use this Body Mass Index (BMI) Table for Adults to quickly check BMI ranges based on your height and weight. This easy-to-read BMI chart shows underweight, normal weight, overweight, and obese categories for adults. Save this helpful BMI reference chart for quick access and share it with others interested in understanding their BMI range.
What Is Waist-to-Height Ratio?
BMI tells you how your weight relates to your height, but it does not show where body fat is carried.
This is one reason our calculator also offers an optional waist-to-height ratio (WHtR) calculation.
The formula is simple:
Waist-to-Height Ratio = Waist Circumference ÷ Height
Your waist and height must be measured using the same unit.
For example, if your waist circumference is 80 cm and your height is 170 cm:
80 ÷ 170 = 0.47
A simple guideline for adults is to try to keep waist circumference at less than half of height, corresponding to a waist-to-height ratio below 0.5. Waist-to-height ratio is also a screening measure and should not be used on its own to diagnose a health condition.
Why Use BMI and Waist-to-Height Ratio Together?
BMI and waist-to-height ratio provide different information.
BMI compares your overall weight with your height.
Waist-to-height ratio considers the size of your waist relative to your height and provides information about central adiposity.
Using the two measurements together can provide additional context, but neither replaces a professional health assessment.
Limitations of BMI
BMI is convenient and widely used, but it has several important limitations.
BMI Does Not Directly Measure Body Fat
BMI is calculated entirely from height and weight. It cannot tell how much of your weight comes from fat, muscle, bone, or other tissues.
BMI Can Be Misleading for Muscular People
Athletes, bodybuilders, and other people with substantial muscle mass may have a relatively high BMI even when they do not have a high level of body fat.
BMI Does Not Show Fat Distribution
Where body fat is stored can also be relevant to health. BMI cannot distinguish between fat stored around the waist and fat stored elsewhere in the body.
Individual Health Is More Complex Than BMI
Age, body composition, medical history, ethnicity, lifestyle, medications, pregnancy, and other factors can affect how body weight and health risk should be assessed.
For these reasons, BMI should be treated as a screening measure rather than a diagnosis.
Who Should Use This BMI Calculator?
Our BMI calculator is designed for adults aged 20 years and older.
It can be used by adult men and women because the standard adult BMI categories are generally applied regardless of sex.
Children and Teenagers
BMI is interpreted differently for people aged 2–19. Children and teenagers should use a dedicated BMI-for-age calculator, where BMI is interpreted using age- and sex-specific percentiles.
Pregnancy
Standard adult BMI calculations using current pregnancy weight are not appropriate for assessing weight status during pregnancy. Healthcare professionals may instead use pre-pregnancy BMI when discussing appropriate pregnancy weight gain.
Athletes and Highly Muscular Adults
BMI may overestimate weight-related risk in some people with high muscle mass. Consider BMI alongside other measurements and professional advice when appropriate.
How to Use Our BMI Calculator
Using the calculator takes only a few seconds.
- Choose Metric or Imperial units.
- Enter your height.
- Enter your weight.
- Optionally enter your waist circumference.
- Select Calculate My BMI.
- Review your BMI, BMI category, estimated healthy weight range, and waist-to-height ratio if provided.
You can reset the calculator at any time and enter new measurements.
Your BMI result should be used for general informational and screening purposes only.
What Is BMI Used For?
BMI is commonly used as a simple screening measure of weight relative to height. For individuals, it can help identify weight categories that may warrant further assessment. At the population level, BMI is also useful for tracking weight-related trends.
BMI should not be used as a diagnosis on its own. Healthcare professionals may consider it alongside medical history, lifestyle, physical examination findings, blood pressure, laboratory results, and other measurements.
Frequently Asked Questions About BMI
1. What is BMI and what does a BMI calculator tell me?
Body Mass Index (BMI) is a screening measure that compares your weight with your height. A BMI calculator uses these two measurements to estimate your BMI and place the result into a general adult weight category, such as underweight, healthy weight, overweight, or obesity.
BMI can be a useful starting point for understanding weight status, but it does not directly measure body fat or diagnose a health condition. It is best considered alongside other factors such as waist measurement, lifestyle, medical history, and advice from a healthcare professional.
2. What is considered a healthy BMI for adults?
For most adults, the standard BMI categories are:
- Underweight: below 18.5
- Healthy weight: 18.5 to 24.9
- Overweight: 25.0 to 29.9
- Obesity: 30.0 or above
These ranges are commonly used as a screening tool to classify weight relative to height. However, being within a particular BMI category does not by itself determine whether someone is healthy or unhealthy. Other health measurements and individual circumstances should also be considered.
3. Is BMI accurate for everyone?
BMI is useful for population-level screening and as a quick estimate of weight status, but it has important limitations. It does not distinguish between muscle, fat, and bone mass or show where body fat is stored.
For example, someone with a high amount of muscle may have a higher BMI without having excess body fat. BMI should therefore be viewed as one health indicator rather than a complete assessment of your body composition or overall health.
4. Why does this BMI calculator also show waist-to-height ratio?
Waist-to-height ratio provides additional information about how much fat may be carried around the waist. This is useful because BMI alone does not show where body fat is distributed.
To calculate it, divide your waist circumference by your height using the same units. As a simple general guideline, adults are often advised to try to keep their waist circumference to less than half of their height, which corresponds to a waist-to-height ratio below 0.5.
Using waist-to-height ratio alongside BMI can provide a more complete picture than BMI alone, particularly when assessing central body fat.
5. Can children or teenagers use this BMI calculator?
This calculator is designed for adults and should not be used to interpret the weight status of children or teenagers.
For people aged 2 to 19, BMI is interpreted differently because children are still growing. Their results are usually assessed using BMI-for-age percentiles, which take age and sex into account.
Parents or caregivers who are concerned about a child’s growth or weight should use an appropriate child and teen BMI tool and discuss the results with a qualified healthcare professional.
6. Can I use BMI during pregnancy?
A standard adult BMI calculator is not suitable for assessing weight status during pregnancy because normal pregnancy-related weight gain changes body weight over time.
Healthcare professionals may use a person’s pre-pregnancy BMI when discussing appropriate pregnancy weight-gain goals, but BMI calculated using current pregnancy weight should not be interpreted in the same way as a standard adult BMI result.
If you are pregnant and have questions about your weight or appropriate weight gain, speak with your doctor, midwife, or another qualified healthcare professional.
7. What should I do if my BMI is outside the healthy-weight range?
A BMI outside the healthy-weight range does not automatically mean that you have a health problem. BMI is a screening measure and should be interpreted alongside other information such as waist circumference, medical history, physical activity, eating habits, blood pressure, laboratory results, and other health factors.
Consider your result as a starting point for understanding your health rather than a diagnosis. If your BMI is below or above the healthy-weight range, or if you have concerns about your weight, discuss the result with a qualified healthcare professional who can provide advice based on your individual circumstances.
Sources & References
We aim to support important health information with reputable public-health and medical sources.
- Centers for Disease Control and Prevention (CDC) — Body Mass Index information and adult BMI categories.
View CDC BMI information - Centers for Disease Control and Prevention (CDC) — Adult BMI categories and interpretation.
View adult BMI categories - National Institute for Health and Care Excellence (NICE) — Guidance relating to BMI and waist-to-height ratio.
View NICE guidance - World Health Organization (WHO) — Information relating to overweight and obesity.
View WHO information
Sources are provided for general reference. Health guidance may change over time, and individual medical advice should come from a qualified healthcare professional.