Use this free BMI calculator to check your Body Mass Index in kg and cm or in kg with feet and inches. Enter your age, weight, and height to get your BMI, your adult weight category, and an estimated healthy weight range for your height. This tool is for adults aged 20 years and older.
BMI Calculator
Calculate your Body Mass Index (BMI), healthy weight range, and ideal body weight using kg and cm or kg with feet and inches.
Your BMI
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BMI is a screening measure and does not by itself diagnose disease.
BMI Calculator: Calculate Your Body Mass Index Online
Use this free BMI calculator to find your Body Mass Index from your weight and height in a few seconds. You can enter your weight in kilograms and your height in centimeters, or choose the feet-and-inches option if that is how you usually measure height. Along with your BMI result, the calculator shows your weight category, an estimated healthy-weight range for your height, and your ideal body weight.
BMI (Body Mass Index) is one of the most widely used screening tools for checking whether a person's weight is low, healthy, or high for their height. It is quick, free, and needs no special equipment, which is why doctors, pharmacists, and public health programs use it as a first step in weight assessment. This tool works as a simple fitness calculator for adults who want a starting point before planning diet or exercise changes.
How to Use This BMI Calculator
- Enter your age (adults 20 years and older).
- Select your gender and preferred units: kg and cm, or kg with feet and inches.
- Enter your current weight and height.
- Click Calculate BMI to see your BMI, your category, your estimated healthy-weight range, and your ideal body weight.
- Click Reset to clear the form and calculate for another person.
How to Calculate BMI (BMI Formula)
The standard adult BMI calculation formula is: BMI = weight in kilograms ÷ height in meters². This is the same BMI formula used by this calculator.
Example in kg and meters: if you weigh 70 kg and your height is 1.75 m, then 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9, which is in the healthy-weight range.
Formula in pounds and inches: BMI = 703 × weight in pounds ÷ height in inches². Both formulas give the same result.
Weight Formula: Find Weight from BMI and Height
If you already know your BMI and height, you can rearrange the BMI formula to get the weight formula: Weight (kg) = BMI × height in meters². This is how a healthy-weight range is worked out for any height: multiply the lower and upper healthy BMI values (18.5 and 24.9) by your height in meters squared.
Example: for a height of 1.70 m, height² is 2.89. The lower limit is 18.5 × 2.89 = 53.5 kg and the upper limit is 24.9 × 2.89 = 72.0 kg. So a healthy weight for a 1.70 m adult is roughly 53.5 to 72.0 kg.
BMI Calculator in kg and Feet
Many people know their height in feet and inches but their weight in kilograms. This BMI calculator in kg and feet lets you enter weight in kilograms and height in feet and inches, then converts your height automatically before calculating BMI. One foot equals 30.48 cm and one inch equals 2.54 cm.
Example: a person who is 5 ft 7 in (about 170.2 cm) and weighs 70 kg has a BMI of about 24.2.
BMI Calculator in kg and cm
If you know your height in centimeters, choose the kg-and-cm option. The calculator converts centimeters to meters and applies the standard BMI formula. This is the simplest way to calculate BMI in kg and is the most common method in clinics and hospitals.
Adult BMI Categories
After your BMI is calculated, it is compared with standard adult categories used for weight screening:
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to less than 25 | Healthy Weight |
| 25 to less than 30 | Overweight |
| 30 to less than 35 | Obesity — Class 1 |
| 35 to less than 40 | Obesity — Class 2 |
| 40 or greater | Obesity — Class 3 |
BMI Calculator NHS and WHO Ranges
If you are searching for a BMI calculator NHS or a WHO calculator, note that both the UK National Health Service (NHS) and the World Health Organization (WHO) use the same adult BMI ranges shown above: below 18.5 is underweight, 18.5 to 24.9 is a healthy weight, 25 to 29.9 is overweight, and 30 or more falls in the obesity range. This calculator uses those standard ranges, so your result can be compared with NHS and WHO guidance. This page is an independent Medinzo tool and is not an official NHS or WHO calculator.
For people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, NHS/NICE guidance and WHO expert advice suggest lower action points, commonly 23 for increased risk and 27.5 for high risk, because health problems such as type 2 diabetes can develop at a lower BMI.
Healthy Weight Range by Height
A healthy BMI of 18.5 to 24.9 corresponds to a different weight range for each height. The table below shows approximate healthy weight for height values for adults. Your own range is also shown in the calculator result.
| Height | Healthy weight range (approx.) |
|---|---|
| 5 ft 0 in (152.4 cm) | 43.0 – 57.8 kg |
| 5 ft 2 in (157.5 cm) | 45.9 – 61.8 kg |
| 5 ft 4 in (162.6 cm) | 48.9 – 65.8 kg |
| 5 ft 6 in (167.6 cm) | 52.0 – 70.0 kg |
| 5 ft 8 in (172.7 cm) | 55.2 – 74.3 kg |
| 5 ft 10 in (177.8 cm) | 58.5 – 78.7 kg |
| 6 ft 0 in (182.9 cm) | 61.9 – 83.3 kg |
Weight Calculator as per Height and Age
Many people search for a weight calculator as per height and age. For adults aged 20 and older, the healthy-weight range depends on height, not on age, so the table above applies to adults of any age. Age matters mainly in two ways: children and teenagers need a separate BMI-for-age chart, and in older adults a slightly higher BMI may be acceptable. If you are over 65 or have a medical condition, ask your doctor what weight is right for you.
Ideal Body Weight (IBW) Calculator in kg
Ideal body weight (IBW) is an estimated weight for a person's height and sex. It is different from a BMI range because it gives one estimated figure instead of a range. This page works as an ideal weight calculator in kg: after you click Calculate BMI, the result also shows your IBW using the Devine formula, based on the gender you select. Doctors and pharmacists often use IBW to calculate certain medicine doses.
IBW Formula (Devine Formula)
The most commonly used IBW formula is the Devine formula, which applies to adults taller than 5 feet (60 inches):
- Men: IBW (kg) = 50 + 2.3 × (height in inches − 60)
- Women: IBW (kg) = 45.5 + 2.3 × (height in inches − 60)
Example: a man who is 5 ft 10 in (70 inches) has an IBW of 50 + 2.3 × 10 = 73.0 kg. A woman who is 5 ft 4 in (64 inches) has an IBW of 45.5 + 2.3 × 4 = 54.7 kg.
Ideal Body Weight Formula: Other Methods
Besides Devine, other commonly cited ideal body weight formulas include Robinson, Miller, and Hamwi. They give slightly different results, which is why IBW should be treated as an estimate only.
| Formula | Men (kg) | Women (kg) |
|---|---|---|
| Devine | 50 + 2.3 per inch over 5 ft | 45.5 + 2.3 per inch over 5 ft |
| Robinson | 52 + 1.9 per inch over 5 ft | 49 + 1.7 per inch over 5 ft |
| Miller | 56.2 + 1.41 per inch over 5 ft | 53.1 + 1.36 per inch over 5 ft |
| Hamwi | 48 + 2.7 per inch over 5 ft | 45.5 + 2.2 per inch over 5 ft |
Ideal Body Weight by Height (Devine)
| Height | IBW — Men | IBW — Women |
|---|---|---|
| 5 ft 0 in (152.4 cm) | 50.0 kg | 45.5 kg |
| 5 ft 2 in (157.5 cm) | 54.6 kg | 50.1 kg |
| 5 ft 4 in (162.6 cm) | 59.2 kg | 54.7 kg |
| 5 ft 6 in (167.6 cm) | 63.8 kg | 59.3 kg |
| 5 ft 8 in (172.7 cm) | 68.4 kg | 63.9 kg |
| 5 ft 10 in (177.8 cm) | 73.0 kg | 68.5 kg |
| 6 ft 0 in (182.9 cm) | 77.6 kg | 73.1 kg |
IBW formulas were designed for clinical estimates and do not account for muscle mass, bone structure, or ethnicity. For personal goals, the BMI healthy-weight range is usually more practical than a single IBW number.
BMI Calculator for Men and Women
The standard adult BMI formula and BMI categories are the same for men and women, so this works as a BMI calculator for men and a BMI calculator for women. The gender option is used for the ideal body weight estimate. However, at the same BMI, women generally carry more body fat than men, and body composition can differ between individuals. BMI does not directly measure body fat or distinguish muscle from fat, so it should be interpreted alongside other health information such as waist circumference, blood pressure, and blood tests.
BMI Calculator with Age
This is a BMI calculator with age for adults aged 20 years and older. Age is not directly included in the standard adult BMI formula, but it decides which method should be used: adults use the standard BMI categories, while children and teenagers require a separate BMI-for-age calculation. In older adults, a slightly higher BMI is sometimes acceptable, so results are best discussed with a doctor.
BMI Calculator Pakistan
If you are looking for a BMI calculator Pakistan, the same standard adult BMI formula can be used. Enter your weight in kilograms and height in centimeters, or use the feet-and-inches option, which is how height is commonly measured in Pakistan.
Please note that some health organizations suggest lower BMI action points for South Asian populations, because health risks such as type 2 diabetes and heart disease can appear at a lower BMI. This calculator shows the standard adult categories, so if you are South Asian, discuss your result with a doctor even when it falls in the upper part of the healthy range.
BMI as a Fitness Calculator
BMI is often the first number people check on a fitness calculator, but it is only one part of fitness. A fuller picture also includes waist circumference, body-fat percentage, resting heart rate, blood pressure, strength, and stamina. Use your BMI as a starting point, then track changes in your weight, waist size, and energy levels over time rather than relying on one number.
Is BMI the Same as Body Fat?
No. BMI is calculated from weight and height only. It is a screening measure and does not directly measure body-fat percentage or fat distribution. A muscular person or athlete may have a high BMI with low body fat, while another person may have a normal BMI with a high amount of body fat.
Limitations of BMI
- It does not separate muscle, bone, and fat.
- It does not show where fat is stored (abdominal fat carries higher health risk).
- It may be less accurate for athletes, bodybuilders, older adults, and people with very short or very tall height.
- It is not a diagnosis and should not be used alone to make health decisions.
BMI Calculator for Children
This calculator is intended for adults aged 20 and older. Children and teenagers aged 2 to 19 should be assessed using BMI-for-age percentiles, which account for age and sex because body composition changes as children grow.
When to Talk to a Doctor
Speak with a doctor or qualified healthcare professional if your BMI is below 18.5 or above 25, if your weight has changed suddenly without a clear reason, or if you have conditions such as diabetes, high blood pressure, thyroid disease, or heart disease. A healthcare professional can assess your overall health and advise a safe plan for weight management.
Frequently Asked Questions
What is BMI?
BMI stands for Body Mass Index. It is a calculated measure of weight relative to height, used to screen for underweight, healthy weight, overweight, and obesity in adults.
How do I calculate my BMI?
Divide your weight in kilograms by your height in meters squared. Or simply enter your weight and height in the calculator above.
What is the BMI calculation formula?
BMI = weight in kilograms ÷ height in meters². In pounds and inches, the formula is BMI = 703 × weight (lb) ÷ height (in)².
What is the weight formula using BMI and height?
Weight (kg) = BMI × height in meters². For example, at a BMI of 22 and a height of 1.70 m, the weight is 22 × 2.89 = 63.6 kg.
What is the IBW formula?
The Devine IBW formula is 50 kg + 2.3 kg for each inch over 5 feet for men, and 45.5 kg + 2.3 kg for each inch over 5 feet for women.
What is ideal body weight?
Ideal body weight is an estimated healthy weight for a person's height and sex, calculated with formulas such as Devine, Robinson, Miller, or Hamwi. It is an estimate, not a personal target.
Is this the same as the NHS or WHO BMI calculator?
This is an independent Medinzo calculator, but it uses the same standard adult BMI ranges as the NHS and WHO: below 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, and 30 or above obesity.
Can I calculate BMI using kg and feet?
Yes. Select the kg and feet/inches option, then enter your weight in kilograms and your height in feet and inches. The calculator converts your height automatically.
What is a healthy BMI for adults?
A BMI from 18.5 to less than 25 is commonly classified as healthy weight for adults.
Is BMI different for men and women?
The standard adult BMI formula and categories are the same for men and women. Body fat percentage at the same BMI can differ between sexes.
Does age affect BMI?
Age is not directly included in the standard adult BMI formula, but age determines whether adult BMI or BMI-for-age should be used.
Can children use this BMI calculator?
No. Children and teenagers require BMI-for-age percentile interpretation.
Is BMI a diagnosis?
No. BMI is a screening measure and should not be used alone to diagnose a health condition.
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Medical Disclaimer
This calculator is for general educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your weight and health.