BMI Calculator

Calculate your Body Mass Index globally

Gender

years (2–120)
cm
kg

What is the BMI Calculator?

The BMI Calculator (Body Mass Index Calculator) is a free online health tool that helps you quickly assess whether your weight is appropriate for your height. BMI is a widely used screening metric endorsed by the World Health Organization (WHO) and health departments worldwide. It provides a simple numerical value that categorises individuals into underweight, normal weight, overweight, or obese ranges. This tool is useful for adults who want to monitor their weight status, set fitness goals, or track progress over time. It is commonly used by doctors, nutritionists, gym trainers, and fitness-conscious individuals. Our calculator supports both metric (kg/cm) and imperial (lbs/inches) units, and also provides personalised health insights including ideal weight range and BMI category with colour-coded visual gauge.

How to Use the BMI Calculator

  1. 1. Select your preferred unit system — Metric (kg, cm) or Imperial (lbs, ft/in).
  2. 2. Enter your height using the slider or the input field.
  3. 3. Enter your weight using the slider or the input field.
  4. 4. Your BMI value and weight category are displayed instantly.
  5. 5. Review the gauge, ideal weight range, and health tips provided below the result.

Formula Used

BMI = Weight (kg) / Height² (m²)

Where Weight is in kilograms and Height is in metres. For imperial units, the formula is BMI = (Weight in lbs × 703) / Height² (in inches²). BMI categories: Underweight < 18.5 | Normal weight 18.5–24.9 | Overweight 25–29.9 | Obese ≥ 30.

Practical Example

A person weighing 70 kg with a height of 1.75 m: BMI = 70 / (1.75 × 1.75) = 70 / 3.0625 ≈ 22.9. This falls in the Normal weight range (18.5–24.9), indicating a healthy weight status. Another example: a person weighing 90 kg at 1.70 m height has BMI = 90 / 2.89 ≈ 31.1, which is classified as Obese (BMI ≥ 30), suggesting a need for lifestyle changes under medical guidance.

Why Use Our BMI Calculator?

  • • Supports both metric and imperial units — works for users worldwide.
  • • Visual BMI gauge instantly shows your position within all health categories.
  • • Provides ideal weight range and personalised health insights alongside the BMI value.
  • • Free, no registration needed, fully responsive on mobile devices.

Frequently Asked Questions

What is a healthy BMI range?

For adults, a BMI between 18.5 and 24.9 is considered healthy or normal weight. A BMI below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is classified as obese. These WHO-endorsed thresholds are widely used in medical and fitness assessments.

Is BMI accurate for everyone?

BMI may not be perfectly accurate for athletes and people with high muscle mass (as muscle weighs more than fat), elderly individuals who have lost muscle mass, or children and pregnant women. It is a useful general screening tool but should not replace a comprehensive medical evaluation.

How often should I check my BMI?

If you are actively managing your weight, checking every 3 to 6 months is reasonable to track progress. For general health monitoring, an annual check is sufficient. Avoid checking too frequently as BMI changes gradually and short-term fluctuations are not meaningful indicators.

What is the difference between BMI and body fat percentage?

BMI is calculated from height and weight alone and is a simple screening metric. Body fat percentage directly measures the proportion of fat in your body and is considered more accurate. It requires specialised tools like DEXA scans or bioelectrical impedance. BMI is free and instant; body fat percentage needs measurement equipment.

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