BMI Calculator
Enter your details below to calculate your Body Mass Index and view your health metrics.
Your Information
Your Results
PCOS Blocking Your Weight Loss?
Standard calorie deficits miserably fail when insulin resistance and high cortisol force your body to store fat. Don't starve yourself. Fix the hormonal root cause in just 21 days.
Start The 21-Day PCOS ProtocolAbout This Calculator
Definition of BMI
Body Mass Index (BMI) is a simple numerical measurement derived from an individual's height and weight. It serves as a screening tool to categorize whether a person is underweight, has a healthy weight, is overweight, or has obesity.
BMI was invented by Belgian mathematician Adolphe Quetelet in the early 19th century and is sometimes referred to as the Quetelet Index. It is widely used by healthcare professionals and public health organizations worldwide to assess body weight status and associated health risks.
BMI Formula
The BMI formula calculates body mass index by dividing weight by the square of height:
Metric Units:
BMI = mass (kg) / height² (m²)
Imperial/US Units:
BMI = 703 × mass (lbs) / height² (in²)
Example: A person weighing 70 kg with a height of 1.75 m would have a BMI of 22.9 kg/m²
Purpose of BMI
The BMI calculator serves several important purposes for individuals and healthcare providers:
- Health Risk Assessment: BMI helps identify individuals who may be at increased risk for weight-related health conditions such as type 2 diabetes, heart disease, and high blood pressure.
- Public Health Monitoring: Health organizations use BMI data to track obesity rates and plan intervention programs at population levels.
- Weight Management: Individuals can use BMI to set realistic health and fitness goals and track progress over time.
- Insurance Assessment: Many insurance companies consider BMI when evaluating health insurance premiums and coverage eligibility.
- Clinical Screening: Healthcare providers use BMI as an initial screening tool to determine if further evaluation is needed.
BMI Categories
According to the World Health Organization (WHO) standards, BMI categories for adults (age 20+) are:
| Classification | BMI range (kg/m²) |
|---|---|
| Severe Thinness | < 16 |
| Moderate Thinness | 16 - 17 |
| Mild Thinness | 17 - 18.5 |
| Normal | 18.5 - 25 |
| Overweight | 25 - 30 |
| Obese Class I | 30 - 35 |
| Obese Class II | 35 - 40 |
| Obese Class III | > 40 |
Health Indication
BMI provides important indicators about potential health risks associated with different weight categories:
Risks of Being Overweight
Being overweight increases the risk of:
- Type 2 diabetes
- Heart disease and stroke
- High blood pressure
- Gallbladder disease
- Osteoarthritis
- Sleep apnea and breathing problems
- Certain cancers (endometrial, breast, colon)
- Mental health issues including depression and anxiety
Risks of Being Underweight
Being underweight can indicate:
- Malnutrition and vitamin deficiencies
- Osteoporosis (bone weakness)
- Decreased immune function
- Growth and development issues in children
- Reproductive issues in women
- Increased risk of complications from surgery
Limitations of BMI
While BMI is a useful screening tool, it has several important limitations:
In Adults:
- BMI does not distinguish between muscle mass and body fat
- Muscular individuals and athletes may have high BMI despite low body fat
- Older adults tend to have more body fat than younger adults with the same BMI
- Women generally have more body fat than men for an equivalent BMI
- BMI does not account for fat distribution (e.g., visceral vs. subcutaneous fat)
- Ethnic differences in body composition are not considered
In Children and Adolescents:
- Height and level of sexual maturation affect BMI
- Different percentile references are used for boys and girls
- BMI is a better indicator of excess body fat for obese than overweight children
Additional Health Measures
For a more comprehensive health assessment, consider these additional measurements:
- Waist-to-Hip Ratio (WHR): Measures fat distribution around the abdomen and hips.
- Waist-to-Height Ratio: Better indicator of central obesity than BMI alone.
- Body Fat Percentage: Direct measurement of fat mass relative to total weight.
- Ponderal Index: Similar to BMI but accounts for body shape differences.
- Basal Metabolic Rate (BMR): Measures calories burned at rest.
WHO Standard Reference
The World Health Organization (WHO) established the international BMI classification system in the 1990s. Key references include:
The WHO recommends that BMI be used as a general indicator of population health rather than a diagnostic tool for individuals. Clinical judgment should always be applied when making health assessments.
BMI Chart
Use this BMI chart to quickly find your BMI based on your height and weight. Green highlighted cells indicate healthy BMI range (18.5-25):
| Height | 50 kg 110 lbs |
55 kg 121 lbs |
60 kg 132 lbs |
65 kg 143 lbs |
70 kg 154 lbs |
75 kg 165 lbs |
80 kg 176 lbs |
85 kg 187 lbs |
90 kg 198 lbs |
|---|---|---|---|---|---|---|---|---|---|
| 5'0" (152 cm) | 22 | 24 | 26 | 28 | 30 | 32 | 35 | 37 | 39 |
| 5'1" (155 cm) | 21 | 23 | 25 | 27 | 29 | 31 | 33 | 36 | 38 |
| 5'2" (157 cm) | 20 | 22 | 24 | 26 | 28 | 30 | 32 | 35 | 37 |
| 5'3" (160 cm) | 20 | 21 | 23 | 25 | 27 | 29 | 31 | 33 | 35 |
| 5'4" (163 cm) | 19 | 21 | 23 | 24 | 26 | 28 | 30 | 32 | 34 |
| 5'5" (165 cm) | 18 | 20 | 22 | 24 | 26 | 28 | 30 | 31 | 33 |
| 5'6" (168 cm) | 18 | 20 | 21 | 23 | 25 | 27 | 29 | 30 | 32 |
| 5'7" (170 cm) | 17 | 19 | 21 | 22 | 24 | 26 | 28 | 29 | 31 |
| 5'8" (173 cm) | 17 | 19 | 20 | 22 | 24 | 25 | 27 | 28 | 30 |
| 5'9" (175 cm) | 16 | 18 | 20 | 21 | 23 | 24 | 26 | 28 | 29 |
| 5'10" (178 cm) | 16 | 18 | 19 | 21 | 22 | 24 | 25 | 27 | 28 |
| 5'11" (180 cm) | 15 | 17 | 19 | 20 | 22 | 23 | 25 | 26 | 28 |
| 6'0" (183 cm) | 15 | 17 | 18 | 20 | 21 | 23 | 24 | 25 | 27 |
BMI for Children and Adolescents (Ages 5-18)
Body fat of children changes rapidly as they grow. Since their growth is an ongoing curve, BMI ranges for children and teens differ from adult BMI ranges. In the United States, BMI for children is measured for individuals aged 2-20 years using age- and sex-specific percentile charts.
A BMI between the 5th and 85th percentile is considered healthy for children. BMI at or above the 95th percentile indicates obesity, while below the 5th percentile indicates underweight.
Unlike adult BMI, children's BMI percentiles differ for boys and girls due to differences in growth patterns and body composition.
Body Mass Index (BMI) Percentiles for Girls (Ages 5-18)
Source: CDC Growth Charts
| Age | 5th | 15th | 50th | 85th | 95th |
|---|---|---|---|---|---|
| 5 yrs | 13.0 | 14.0 | 15.6 | 17.5 | 18.9 |
| 6 yrs | 13.1 | 14.2 | 15.9 | 17.9 | 19.4 |
| 7 yrs | 13.3 | 14.5 | 16.4 | 18.6 | 20.3 |
| 8 yrs | 13.5 | 14.9 | 17.0 | 19.5 | 21.4 |
| 9 yrs | 13.8 | 15.3 | 17.7 | 20.4 | 22.5 |
| 10 yrs | 14.2 | 15.8 | 18.4 | 21.3 | 23.6 |
| 11 yrs | 14.6 | 16.3 | 19.1 | 22.2 | 24.7 |
| 12 yrs | 15.0 | 16.9 | 19.8 | 23.0 | 25.7 |
| 13 yrs | 15.4 | 17.5 | 20.5 | 23.8 | 26.6 |
| 14 yrs | 15.8 | 18.1 | 21.2 | 24.6 | 27.5 |
| 15 yrs | 16.2 | 18.6 | 21.8 | 25.3 | 28.3 |
| 16 yrs | 16.5 | 19.1 | 22.3 | 25.9 | 28.9 |
| 17 yrs | 16.7 | 19.4 | 22.7 | 26.3 | 29.4 |
| 18 yrs | 16.9 | 19.6 | 23.0 | 26.7 | 29.8 |
Body Mass Index (BMI) Percentiles for Boys (Ages 5-18)
Source: CDC Growth Charts
| Age | 5th | 15th | 50th | 85th | 95th |
|---|---|---|---|---|---|
| 5 yrs | 13.3 | 14.3 | 15.8 | 17.7 | 19.1 |
| 6 yrs | 13.5 | 14.5 | 16.1 | 18.1 | 19.6 |
| 7 yrs | 13.7 | 14.9 | 16.6 | 18.8 | 20.4 |
| 8 yrs | 14.0 | 15.3 | 17.2 | 19.6 | 21.4 |
| 9 yrs | 14.3 | 15.7 | 17.8 | 20.4 | 22.4 |
| 10 yrs | 14.6 | 16.2 | 18.4 | 21.2 | 23.4 |
| 11 yrs | 15.0 | 16.7 | 19.1 | 22.1 | 24.5 |
| 12 yrs | 15.4 | 17.3 | 19.8 | 23.0 | 25.6 |
| 13 yrs | 15.9 | 17.9 | 20.6 | 24.0 | 26.8 |
| 14 yrs | 16.4 | 18.6 | 21.4 | 25.0 | 28.0 |
| 15 yrs | 16.9 | 19.3 | 22.2 | 25.9 | 29.1 |
| 16 yrs | 17.5 | 20.0 | 22.9 | 26.7 | 30.0 |
| 17 yrs | 18.0 | 20.6 | 23.6 | 27.4 | 30.8 |
| 18 yrs | 18.4 | 21.1 | 24.2 | 28.0 | 31.5 |
Scientific References & Medical Citations
1. World Health Organization. (2004). Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. The Lancet, 363(9403), 157–163.
2. Nuttall, F. Q. (2015). Body Mass Index: Obesity, BMI, and Health: A Critical Review. Nutrition Today, 50(3), 117–128.
3. World Health Organization. Obesity and Overweight - Key Facts. [WHO Fact Sheet]
Note: This calculator uses the WHO standard BMI classification and is intended for adults aged 20 years and older.
Medical Disclaimer
This BMI calculator is provided for informational and educational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult your doctor or another qualified healthcare provider if you have any questions about your health or weight.
BMI is only a general screening tool and has some limitations. It does not consider factors such as muscle mass, bone density, body composition, or how fat is distributed in the body. A complete health assessment should include other measurements and a professional medical evaluation.
Note: The results shown in this calculator are approximate values only and should not be considered exact measurements. Actual health assessments may vary from person to person.
If you are concerned about your weight or overall health, please speak with a qualified healthcare professional.