BMI Calculator in KG & CM – Free Body Mass Index Tool

Use this free BMI calculator in kg and cm, kilograms with feet/inches, or stones and pounds to calculate your adult Body Mass Index instantly. Enter your height and weight to see your BMI score, standard adult category and healthy weight range. BMI is a screening measure, not a diagnosis.

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Health information notice: This calculator is for adults aged 18 and over and provides general educational information only. BMI does not diagnose a medical condition or directly measure body fat.

BMI calculator in kg and cm showing adult Body Mass Index and healthy weight range

Calculate Your BMI in KG, CM, Feet or Inches

Choose the height and weight units that match the measurements you have. The calculator supports centimetres or feet/inches for height and kilograms or stones/pounds for weight, including mixed combinations such as kilograms with feet and inches.

Centimeters
Kilograms
Reset

Your BMI will appear here

Enter your height and weight, then select Calculate.

What your result means

Enter valid values to see guidance.

What the calculator shows

Your result is shown as BMI in kg/m² together with the standard adult BMI category and the healthy-weight range calculated from your height. Results are rounded for readability.

Why Use This BMI Calculator?

Instant result

Enter your height and weight and calculate your BMI without creating an account.

Flexible units

Use kg, cm, feet, inches, stones or pounds without manually converting measurements.

Adult BMI category

See the standard adult BMI classification alongside your calculated score.

How to Calculate BMI in KG and CM

For metric measurements, convert height from centimetres to metres, square the height in metres, then divide weight in kilograms by that number. The calculator performs this automatically.

  • Step 1: Enter your height, for example 170 cm.
  • Step 2: Enter your weight, for example 65 kg.
  • Step 3: Select Calculate to see your BMI and adult category.

BMI Formula: Metric and Imperial

  • Metric: BMI = weight (kg) ÷ height (m)²
  • Imperial: BMI = 703 × weight (lb) ÷ height (in)²

The numerical BMI result is expressed in kg/m². The unit controls are there to make data entry easier; the calculator handles the required conversion before calculating the result.

BMI Example: 65 KG at 170 CM

Example: 170 cm = 1.70 m. For a weight of 65 kg, the calculation is 65 ÷ (1.70 × 1.70) = 22.5.

BMI result: 22.5. This falls within the standard healthy adult BMI range of 18.5 to 24.9. At a height of 1.70 m, the equivalent standard healthy-weight range is approximately 53.5 kg to 72.0 kg.

Adult BMI Categories

For most adults aged 18 and over, the NHS and WHO use the standard BMI thresholds below. These categories are screening classifications and should be interpreted alongside other health information.

Adult BMIStandard classificationWhat it means on this calculator
Below 18.5UnderweightBelow the standard healthy adult BMI range
18.5–24.9Healthy weightWithin the standard healthy adult BMI range
25.0–29.9OverweightAbove the standard healthy adult BMI range
30.0 or aboveObesityWithin the standard adult obesity classification

Important: The previous age-banded BMI table has been removed. Standard adult BMI categories are not replaced by progressively higher ‘healthy’ ranges simply because an adult is older.

BMI and South Asian Ethnic Backgrounds

BMI is calculated with the same height-and-weight formula, but health-risk thresholds can be lower for some ethnic groups. This is particularly relevant to many people from South Asian backgrounds.

Current NHS guidance says adults from South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds may be at risk of health problems at a lower BMI. The NHS uses 23 to 27.4 as overweight and 27.5 or above as obesity for these groups.

For personalised interpretation, use the current NHS overweight and obesity guidance or speak with an appropriate healthcare professional.

Can I Calculate BMI in KG and Feet?

Yes. On this calculator, height and weight units can be selected independently. You can enter weight in kilograms while entering height in feet and inches, and the calculator will convert the measurements before applying the BMI formula.

  • KG + CM: useful if both measurements are metric.
  • KG + FT/IN: useful if you know your weight in kilograms but your height in feet and inches.
  • ST/LB + FT/IN: useful for UK-style imperial measurements.

You do not need to perform the conversion yourself. Enter the measurements you know and select the matching unit beside each field.

What BMI Can and Cannot Tell You

BMI is a simple screening measure based on height and weight. It can help place an adult into a broad weight category, but it does not directly measure body fat, muscle mass, body composition or overall health.

  • A muscular or athletic person can have a higher BMI without having the same body-fat level as another person with the same BMI.
  • Pregnancy changes the meaning of weight-based measures, so this adult BMI tool should not be used to assess pregnancy-related weight.
  • BMI should not be used on its own to diagnose a health condition or decide treatment.
  • Waist measurement and other clinical information may add useful context for some adults.

For a deeper explanation, read BMI vs body fat percentage.

Can Children and Teenagers Use This BMI Calculator?

This DiuMitra calculator is intended for adults aged 18 and over. Children and teenagers aged 2 to 17 need an age- and sex-specific BMI assessment rather than the fixed adult categories shown on this page.

For someone aged 2 to 17, use the NHS BMI calculator for children and teenagers. A parent, carer or healthcare professional can help interpret the result where appropriate.

Official BMI Sources and Further Guidance

The classification and interpretation notes on this page are based on current NHS and World Health Organization information. Health guidance can change, so these official sources should take priority over summaries.

Last reviewed for source accuracy: 16 August 2026.

BMI Calculator – Frequently Asked Questions

Divide weight in kilograms by height in metres squared. For example, 65 kg at 170 cm is calculated as 65 ÷ (1.70 × 1.70), which gives a BMI of about 22.5. This calculator performs the conversion and calculation automatically.

Yes. Select feet/inches for height and kilograms for weight. The calculator accepts the mixed units and converts them before calculating BMI, so you do not need to convert your height into centimetres manually.

For most adults, the standard healthy BMI range is 18.5 to 24.9. BMI is a screening measure rather than a diagnosis, and health-risk thresholds can be lower for some ethnic backgrounds.

A person who is 170 cm tall and weighs 65 kg has a BMI of approximately 22.5. Under the standard adult classification, that falls within the 18.5 to 24.9 healthy-weight range.

The standard adult BMI calculation uses the same height-and-weight formula for men and women. Individual health interpretation can still differ because BMI does not measure body composition, fat distribution or other clinical factors.

The adult BMI formula does not change with age. Older adults may still need individual interpretation because muscle mass, health conditions and other factors can affect what a BMI result means for them.

Yes, health-risk thresholds can be lower. NHS guidance uses BMI 23 to 27.4 as overweight and 27.5 or above as obesity for adults from South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean backgrounds.

BMI is useful for broad adult screening but it does not directly measure body fat, muscle mass or overall health. It can be less informative for some muscular people and should not be used as a stand-alone medical assessment.

Important Health Information

This page is for general educational information only and is not medical advice. BMI is a screening measure and cannot diagnose health conditions. If you are concerned about your weight, unexplained weight change, pregnancy, an eating disorder, or another health issue, seek advice from an appropriate healthcare professional.