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BMI Calculator

Calculate your body mass index (BMI) in your browser with this free BMI calculator.

About BMI Calculator

Calculate your body mass index (BMI) in your browser with this free BMI calculator. Switch between metric (kg and cm) and imperial (lb, feet, and inches). The result uses adult WHO ranges: underweight (under 18.5), normal weight (18.5 to 24.9), overweight (25.0 to 29.9), and obesity (30.0 or higher). This tool is informational only - it is not medical advice and is not meant for children or pregnancy.

How to Use BMI Calculator

  1. Choose metric (kg, cm) or imperial (lb, ft, in).
  2. Enter height and weight. Imperial height can be feet plus leftover inches.
  3. Read BMI (one decimal) and the matching adult WHO category instantly.
  4. Copy the BMI value if you need it elsewhere. Change any field to recalculate - no signup required.

BMI Calculator Examples

Metric healthy range

70 kg at 175 cm → BMI 22.9, normal weight (18.5 to 24.9).

Imperial example

150 lb at 5 ft 5 in (65 in) → BMI 25.0, overweight (25.0 to 29.9).

Underweight example

50 kg at 170 cm → BMI 17.3, underweight (under 18.5).

Obesity example

110 kg at 170 cm → BMI 38.1, obesity (30.0 or higher).

Read the full guide

How to Use BMI Calculator: Complete Guide (2026) - 5 min read

Frequently Asked Questions about BMI Calculator

How is BMI calculated?
Metric: BMI = weight (kg) / [height (m)] squared. Height is entered in cm and converted to meters. Imperial: BMI = 703 x weight (lb) / [height (in)] squared. The 703 factor matches the usual adult formula used by public-health charts.
What do the BMI categories mean?
This tool uses adult WHO cutoffs: underweight below 18.5, normal weight 18.5 to 24.9, overweight 25.0 to 29.9, and obesity 30.0 or higher. Categories describe ranges on a chart - they are not a diagnosis.
Is this medical advice?
No. BMI is a screening number from height and weight only. It does not measure body fat, muscle, or health. Talk to a clinician before using BMI to make health decisions. The calculator is not for children, teens, or pregnancy.
Can I use metric and imperial units?
Yes. Switch Metric for kilograms and centimeters, or Imperial for pounds, feet, and inches. Switching units converts the values you already entered so the BMI stays in the same ballpark.
Does my height or weight leave my device?
No. The BMI calculator runs entirely in your browser. Measurements are not uploaded or stored on a server.

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