BMI Calculator – Calculate Your Body Mass Index Online

BMI

24.2

Normal

Age (years)23

Weight (kg)70

Height (cm)

020050080110140170200230260290320

170

Your Health Summary

Healthy BMI Range : 18.5 kg/m² - 25 kg/m²

Healthy Weight for Height : 53.5 kg - 72.2 kg

BMI Prime : 0.97

Ponderal Index : 14.2 kg/m³

Weight Adjustment : You're in a healthy range! Keep up the great habits! 🎉💪

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BMI Calculator – Calculate Your Body Mass Index Instantly

The Body Mass Index (BMI) Calculator is a free online tool that allows you to calculate your BMI and understand your weight category based on your height, weight, age, and gender. By entering your measurements, you can quickly see whether you are underweight, normal weight, overweight, or obese, helping you make informed decisions about your health, fitness, and lifestyle.

Use the Metric Unit button to input your height in centimeters and weight in kilograms, or switch to the Imperial Unit button to use US customary units such as feet, inches, and pounds. The calculator is designed to be simple, fast, and accurate, providing immediate feedback on your body mass index.

Similarly, use the Gender button to select your gender as male or female. This ensures the results are interpreted correctly according to gender-specific BMI references and helps the calculator provide more accurate guidance on your health and weight status.

In addition to BMI, this tool also calculates the Ponderal Index (PI), which is another measurement of body leanness and corpulence. PI can be particularly useful for very tall or very short individuals. Both BMI and PI results are explained in detail below, including what they mean for your overall health, disease risk, and physical fitness.

Whether you are a teenager, adult, or senior, this calculator provides a reliable starting point to evaluate your body weight in relation to your height, track your weight trends over time, and set realistic goals for a healthy lifestyle.

What is BMI (Body Mass Index)? Meaning, Definition, and Importance

Body Mass Index (BMI) is a widely used measurement that estimates a person’s body fat based on their height and weight. It is designed to provide a quick and simple way to evaluate whether an individual has a healthy body weight relative to their height. BMI is not a direct measurement of body fat, but it serves as an important screening tool for identifying potential weight-related health risks.

The calculated BMI value is categorized into ranges such as underweight, normal weight, overweight, and obese. These categories help highlight whether someone may be at risk of conditions linked to being underweight, such as malnutrition and weakened immunity, or overweight, such as diabetes, heart disease, and joint problems. In some cases, ranges are further divided into subcategories like severely underweight or very severely obese for more precise classification.

While BMI is not a perfect measure—because it does not distinguish between muscle, bone mass, and body fat—it remains a practical and cost-effective tool for both individuals and healthcare professionals. It gives an initial indication of whether further testing, lifestyle changes, or professional medical advice might be necessary.

The calculator on this page uses standard BMI ranges recommended by health organizations to help you better understand your results. You can refer to the BMI tables below to see detailed categories and how your BMI compares to healthy ranges.

BMI Formula: How to Calculate BMI in Metric and US Units

Learn how to calculate BMI using both metric (SI) and imperial (USC) units. Below are the BMI equations with an example calculation for a person who is 5 feet 8 inches tall and weighs 150 pounds.

USC Units:

BMI = 703 \times \frac{\text{mass (lbs)}}{\text{height (in)}^2}

= 703 \times \frac{150}{68^2}

= 22.8 \approx 23.0

SI (Metric) Units:

BMI = \frac{\text{mass (kg)}}{\text{height (m)}^2}

= \frac{68.04}{1.727^2}

= 22.8 \approx 23.0

How to Interpret BMI Results for Adults: Understanding Your Weight Category

The Body Mass Index (BMI) table for adults provides standardized weight classifications based on BMI values and is widely recognized by the World Health Organization (WHO). This table applies to both men and women aged 20 and older, making it one of the most commonly used reference points for determining healthy weight ranges worldwide.

According to the WHO, BMI values are divided into categories such as severe thinness, normal weight, overweight, and multiple classes of obesity (Class I, II, III). These classifications help individuals understand whether their current weight may put them at risk for conditions like malnutrition, heart disease, diabetes, or other weight-related health concerns.

You can view the full WHO BMI classification table below to see how different BMI ranges are categorized and compare your own results with these international health standards.

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

BMI Chart for Adults: Height (Feet/Inches) and Weight (Pounds)

This BMI chart helps you find your Body Mass Index (BMI) value based on your height (in feet and inches) andweight (in pounds). The BMI table below provides estimated BMI scores for adults ranging from 4 feet to 7 feet tall and weights between 100 and 300 pounds. This chart serves as a quickweight-for-height reference without needing to calculate manually.

BMI chart for adults (U.S. units): Heights from 4'0" to 7'0" and weights from 100 to 300 pounds.
Height (ft/in)	100 lb	120 lb	140 lb	160 lb	180 lb	200 lb	220 lb	240 lb	260 lb	280 lb	300 lb
4'0"	30.5	36.6	42.7	48.8	54.9	61.0	67.1	73.2	79.3	85.4	91.5
4'2"	28.1	33.7	39.4	45.0	50.6	56.2	61.9	67.5	73.1	78.7	84.4
4'4"	26.0	31.2	36.4	41.6	46.8	52.0	57.2	62.4	67.6	72.8	78.0
4'6"	24.1	28.9	33.8	38.6	43.4	48.2	53.0	57.9	62.7	67.5	72.3
4'8"	22.4	26.9	31.4	35.9	40.4	44.8	49.3	53.8	58.3	62.8	67.3
4'10"	20.9	25.1	29.3	33.4	37.6	41.8	46.0	50.2	54.3	58.5	62.7
5'0"	19.5	23.4	27.3	31.2	35.2	39.1	43.0	46.9	50.8	54.7	58.6
5'2"	18.3	21.9	25.6	29.3	32.9	36.6	40.2	43.9	47.5	51.2	54.9
5'4"	17.2	20.6	24.0	27.5	30.9	34.3	37.8	41.2	44.6	48.1	51.5
5'6"	16.1	19.4	22.6	25.8	29.0	32.3	35.5	38.7	42.0	45.2	48.4
5'8"	15.2	18.2	21.3	24.3	27.4	30.4	33.4	36.5	39.5	42.6	45.6
5'10"	14.3	17.2	20.1	23.0	25.8	28.7	31.6	34.4	37.3	40.2	43.0
6'0"	13.6	16.3	19.0	21.7	24.4	27.1	29.8	32.5	35.3	38.0	40.7
6'2"	12.8	15.4	18.0	20.5	23.1	25.7	28.2	30.8	33.4	35.9	38.5
6'4"	12.2	14.6	17.0	19.5	21.9	24.3	26.8	29.2	31.6	34.1	36.5
6'6"	11.6	13.9	16.2	18.5	20.8	23.1	25.4	27.7	30.0	32.4	34.7
6'8"	11.0	13.2	15.4	17.6	19.8	22.0	24.2	26.4	28.6	30.8	33.0
6'10"	10.5	12.5	14.6	16.7	18.8	20.9	23.0	25.1	27.2	29.3	31.4
7'0"	10.0	12.0	13.9	15.9	17.9	19.9	21.9	23.9	25.9	27.9	29.9

For example, if you are 5 feet 8 inches tall and weigh160 pounds, your BMI is approximately 24.3, which is within the healthy weight range. Use this BMI chart to quickly compare your weight and height ratio without needing a calculator.

BMI Chart for Adults: Height (cm) and Weight (kg)

This BMI chart helps you find your Body Mass Index (BMI) value based on your height (in cm) and weight (in kg). The BMI table below provides estimated BMI scores for adults ranging from 100 cm to 300 cm tall and weights between 40 and 140 kg. This chart serves as a quickweight-for-height reference without needing to calculate manually.

BMI chart for adults (metric units): Heights from 100 cm to 300 cm and weights from 40 to 140 kg.
Height (cm)	40 kg	50 kg	60 kg	70 kg	80 kg	90 kg	100 kg	110 kg	120 kg	130 kg	140 kg
100	40.0	50.0	60.0	70.0	80.0	90.0	100.0	110.0	120.0	130.0	140.0
110	33.1	41.3	49.6	57.9	66.1	74.4	82.6	90.9	99.2	107.4	115.7
120	27.8	34.7	41.7	48.6	55.6	62.5	69.4	76.4	83.3	90.3	97.2
130	23.7	29.6	35.5	41.4	47.3	53.3	59.2	65.1	71.0	76.9	82.8
140	20.4	25.5	30.6	35.7	40.8	45.9	51.0	56.1	61.2	66.3	71.4
150	17.8	22.2	26.7	31.1	35.6	40.0	44.4	48.9	53.3	57.8	62.2
160	15.6	19.5	23.4	27.3	31.3	35.2	39.1	43.0	46.9	50.8	54.7
170	13.8	17.3	20.8	24.2	27.7	31.1	34.6	38.1	41.5	45.0	48.4
180	12.3	15.4	18.5	21.6	24.7	27.8	30.9	34.0	37.0	40.1	43.2
190	11.1	13.9	16.6	19.4	22.2	24.9	27.7	30.5	33.2	36.0	38.8
200	10.0	12.5	15.0	17.5	20.0	22.5	25.0	27.5	30.0	32.5	35.0
210	9.1	11.3	13.6	15.9	18.1	20.4	22.7	24.9	27.2	29.5	31.7
220	8.3	10.3	12.4	14.5	16.5	18.6	20.7	22.7	24.8	26.9	28.9
230	7.6	9.5	11.3	13.2	15.1	17.0	18.9	20.8	22.7	24.6	26.5
240	6.9	8.7	10.4	12.2	13.9	15.6	17.4	19.1	20.8	22.6	24.3
250	6.4	8.0	9.6	11.2	12.8	14.4	16.0	17.6	19.2	20.8	22.4
260	5.9	7.4	8.9	10.4	11.8	13.3	14.8	16.3	17.8	19.2	20.7
270	5.5	6.9	8.2	9.6	11.0	12.3	13.7	15.1	16.5	17.8	19.2
280	5.1	6.4	7.7	8.9	10.2	11.5	12.8	14.0	15.3	16.6	17.9
290	4.8	5.9	7.1	8.3	9.5	10.7	11.9	13.1	14.3	15.5	16.6
300	4.4	5.6	6.7	7.8	8.9	10.0	11.1	12.2	13.3	14.4	15.6

For example, if you are 170 cm tall and weigh 70 kg, your BMI is approximately 24.2, which is within the healthy weight range. Use this BMI chart to quickly compare your weight and height ratio without needing a calculator.

BMI for Children and Teens (Ages 2–20): Percentile Charts and Interpretation

The Body Mass Index (BMI) for children and teens works differently compared to adults. Since kids are still growing, their body composition changes with age and varies between boys and girls. To account for these differences, the Centers for Disease Control and Prevention (CDC) developed age- and sex-specific growth charts that use BMI percentiles instead of fixed ranges. This ensures a more accurate evaluation of whether a child is underweight, at a healthy weight, or at risk of overweight and obesity.

Unlike adults, where BMI categories are the same across all ages and genders, children's BMI values are compared to peers of the same age and sex. This comparison results in a BMI percentile, which indicates how a child’s BMI measures up against others. For example, a child in the 90th percentile weighs more than 90% of children of the same age and sex. The CDC’s official BMI table for ages 2–20 (shown below) outlines the categories based on percentiles.

Understanding BMI percentiles is important because both being underweight or overweight in childhood can increase the risk of long-term health problems such as diabetes, high blood pressure, and heart disease later in life. Tracking BMI early helps parents, caregivers, and healthcare providers take the right steps to support healthy growth and development.

Refer to the table below to see the BMI percentile categories for children and teens recommended by the CDC.

BMI Category	Percentile Range
Underweight	< 5%
Healthy weight	5% - 85%
At risk of overweight	85% - 95%
Overweight	25 - 30

Limitations of BMI: Why BMI Doesn’t Tell the Whole Story

The Body Mass Index (BMI) is one of the most widely used methods for estimating whether an individual is underweight, at a healthy weight, or overweight. However, BMI has limitations because it does not directly measure body composition. Differences in muscle mass, bone density, fat distribution, sex, and age can make BMI less accurate for certain groups of people. For this reason, BMI should be considered as a screening tool, not a definitive measure of health.

Why BMI May Not Be Accurate for Adults: Muscle, Gender, and Age Factors

For adults, BMI reflects overall weight rather than body fat percentage. It does not differentiate between fat and lean muscle mass. This means two people with the same BMI may have very different health profiles:

Older adults often carry more body fat than younger adults with the same BMI.
Women generally have higher body fat than men at an equivalent BMI.
Athletes and muscular individuals may have high BMIs due to increased muscle mass, not excess fat.
Sedentary adults can appear “normal weight” but still have high body fat levels (sometimes called “skinny fat”).

BMI Limitations in Children and Teens: Growth, Age, and Gender Differences

For children and adolescents, BMI is even more complex because growth patterns vary widely. Age, height, and sexual maturation all influence BMI and body fat percentage. While BMI is a better indicator of excess body fat in obese children, it is less accurate for those who are only overweight or underweight. In thin children, BMI differences may reflect fat-free mass (such as muscle, water, or organs) rather than fat levels.

Despite these limitations, BMI is still a useful screening tool for 90–95% of the population. When combined with other assessments such as waist circumference, physical activity levels, and medical history, BMI can provide valuable insights into whether a person is at risk for weight-related health conditions.

Health Risks of Being Overweight or Obese: Effects on Body and Mind

Carrying excess body weight is more than just a cosmetic concern—it can lead to serious health issues and long-term complications. According to the Centers for Disease Control and Prevention (CDC), being overweight significantly increases the risk of chronic diseases, reduced mobility, and decreased quality of life. Maintaining a BMI below 25 kg/m² is generally recommended, but each individual should consult with their doctor to determine a safe and healthy weight range.

High blood pressure (hypertension)
Unhealthy cholesterol levels (high LDL, low HDL) and high triglycerides
Type II diabetes and insulin resistance
Coronary heart disease and increased risk of heart attack
Stroke and related vascular complications
Gallbladder disease and digestive issues
Osteoarthritis, caused by stress on joints and cartilage breakdown
Sleep apnea and other breathing difficulties
Certain cancers (endometrial, breast, colon, kidney, liver, gallbladder)
Reduced quality of life and daily mobility challenges
Mental health concerns, including depression and anxiety
Chronic body pain and difficulty with physical activity
Increased overall risk of premature mortality

As this list shows, being overweight can affect nearly every aspect of health—from cardiovascular wellness to mental well-being. Taking steps to achieve and maintain a healthy BMI through balanced nutrition, regular exercise, and lifestyle adjustments can greatly reduce these risks and improve long-term health outcomes.

Health Risks of Being Underweight: Nutritional Deficiencies and Weak Immunity

Just as carrying excess weight poses health challenges, being underweight also increases the risk of serious medical and lifestyle complications. A low Body Mass Index (BMI) may be a sign of malnutrition, nutrient deficiencies, or an underlying condition that requires medical attention. Maintaining a balanced weight is essential for strong immunity, healthy growth, and long-term well-being.

Malnutrition, vitamin deficiencies, and anemia (reduced oxygen-carrying capacity)
Osteoporosis and bone weakness, leading to higher fracture risk
Weakened immune system and reduced ability to fight infections
Growth and development issues in children and teenagers
Reproductive issues in women due to hormonal imbalances and menstrual irregularities
Higher risk of miscarriage during the first trimester for underweight women
Increased complications during and after surgery
Elevated overall risk of premature mortality compared to a healthy BMI

In some cases, being underweight may be linked to underlying health conditions such as eating disorders (e.g., anorexia nervosa) or chronic illness. If you or someone you know is underweight without a clear cause, it is important to consult a healthcare professional. Proper evaluation and treatment can help restore a healthy balance, reduce risks, and improve overall quality of life.

What Is BMI Prime? A Smarter Way to Compare Your BMI

BMI Prime is the ratio of a person’s measured Body Mass Index (BMI) to the upper limit of what is considered a normal BMI by organizations such as the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). This upper limit, known as BMI_upper, is typically set at 25 kg/m².

BMI Prime provides a simple, unitless way to understand how your BMI compares to the healthy range.

BMI Prime Formula:

\text{BMI Prime} = \frac{\text{BMI}}{25}

Since BMI Prime is a ratio of two BMI values, it has no units(it’s a dimensionless number). It helps classify whether a person is underweight, normal, overweight, or obese.

Category	BMI	BMI Prime
Severe Thinness	< 16	< 0.64
Moderate Thinness	16 - 17	0.64 - 0.68
Mild Thinness	17 - 18.5	0.68 - 0.74
Normal	18.5 - 25	0.74 - 1
Overweight	25 - 30	1 - 1.2
Obese Class I	30 - 35	1.2 - 1.4
Obese Class II	35 - 40	1.4 - 1.6
Obese Class III	> 40	> 1.6

Example:

\text{If BMI} = 22.5

\text{BMI Prime} = \frac{22.5}{25} = 0.9

This means the person’s BMI Prime is 0.9, which falls within the normal range. BMI Prime helps provide a quick comparison of how a person’s BMI relates to the upper healthy limit and enables meaningful comparisons across groups with different BMI standards or regional thresholds.

Ponderal Index (PI) vs BMI: What’s the Difference?

The Ponderal Index (PI) is a measurement similar to the Body Mass Index (BMI), used to evaluate a person’s leanness or corpulence based on their height and weight. The key difference is that the PI formula cubes the height rather than squaring it, making it more reliable for individuals who are exceptionally tall or short.

While BMI is a useful tool for analyzing large populations, it can sometimes misrepresent body composition for people at the extremes of height. The Ponderal Index adjusts for this by using a cubic height value, providing a more balanced perspective for individuals.

Below is the formula for calculating the Ponderal Index using both USC (Imperial) and SI (Metric) units, demonstrated with an example for a person who is 5 feet 8 inches tall and weighs 150 pounds.

USC Units:

\text{PI} = \frac{\text{mass (lbs)}}{\text{height}^3\text{ (in)}} \times 27666.9

= \frac{150}{68^3} \times 27666.9

= 13.2

SI (Metric) Units:

\text{PI} = \frac{\text{mass (kg)}}{\text{height}^3\text{ (m)}}

= \frac{68.04}{1.727^3}

= 13.2

A higher Ponderal Index indicates a leaner physique, while a lower value suggests a higher level of corpulence. Unlike BMI, PI tends to provide a more consistent indication of body composition across a wide range of heights.