BMI Calculator
Calculate your Body Mass Index using metric or imperial units and see the weight category.
Inputs
Result
Enter values on the left and select Calculate to see the result here.
What the BMI Calculator does
- Calculates Body Mass Index (BMI) from height and weight using either metric or imperial inputs.
- Returns a broad category label: Underweight, Normal weight, Overweight, or Obese.
- Provides a quick screening-style number that can be compared with other health calculators, but it does not diagnose health status.
How to use the BMI Calculator
- Choose metric units for centimetres and kilograms, or imperial units for feet, inches, and pounds.
- Enter height and weight in the fields for the selected unit system.
- Click Calculate to see BMI rounded to 1 decimal place and the broad category label.
- Use related calculators such as Body Fat, BMR, TDEE, and Calorie Calculator for extra context.
Formula / methodology used
- Metric BMI = weight in kilograms ÷ (height in metres × height in metres).
- Imperial BMI = weight in pounds ÷ (height in inches × height in inches) × 703.
- The current category cut-offs in the calculator are: below 18.5 Underweight, 18.5 to below 25 Normal weight, 25 to below 30 Overweight, and 30 or above Obese.
Example calculation
A person is 175 cm tall and weighs 70 kg.
- Height in metres = 175 ÷ 100 = 1.75
- BMI = 70 ÷ (1.75 × 1.75)
- BMI = 22.9 when rounded to 1 decimal place
Result: The calculator returns BMI 22.9 and the category Normal weight.
Common mistakes and limitations
- Entering centimetres in the imperial fields, or pounds in the kilogram field, will produce an incorrect result.
- BMI categories are broad and may not be suitable for children, pregnant people, athletes, or some clinical contexts.
- The result should be interpreted alongside wider health information, not in isolation.
Important note
This calculator provides general educational information only and is not medical, nutritional, fitness, or healthcare advice.
BMI Calculator FAQs
Is BMI a diagnosis?
No. BMI is a broad height-to-weight screening measure. It does not diagnose body composition, fitness, or medical risk.
Can BMI be misleading?
Yes. BMI does not distinguish muscle, fat, bone, age, sex, pregnancy, or ethnicity-related differences.
Which units should I use?
Use metric if you know centimetres and kilograms, or imperial if you know feet, inches, and pounds. The calculator applies the matching formula.
Why compare BMI with body fat percentage?
Body fat estimates use body measurements and can provide different context from BMI, although they are still estimates with limitations.