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UtilLab

BMI Calculator

Enter your height and weight to calculate your Body Mass Index (BMI) and find out which category you fall into.

kg
cm

Formula (metric): BMI = weight (kg) ÷ height² (m)

BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, age, sex, or ethnicity. Consult a healthcare professional for a full health assessment.

Your BMI

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Enter your weight and height

  • UnderweightBelow 18.5
  • Normal weight18.5 – 24.9
  • Overweight25.0 – 29.9
  • Obese30.0 and above

Guide

Understanding your BMI result

How BMI is calculated

Body Mass Index relates weight to height, so people of different sizes can be compared on one scale.

BMI = weight (kg) ÷ height (m)² BMI = 703 × weight (lb) ÷ height (in)²

Example: 70 kg at 1.75 m gives 70 ÷ (1.75 × 1.75) = 22.9, which is in the normal range.

The adult categories

The World Health Organization groups adult BMI as follows: below 18.5 underweight, 18.5 to 24.9 normal, 25.0 to 29.9 overweight and 30.0 or above obese. Next to your result, the calculator also shows the weight range that would put you in the normal band for your height.

What BMI cannot tell you

  • It cannot distinguish muscle from fat, so athletes can score as overweight while being lean.
  • It ignores where fat is stored. Waist circumference and waist-to-hip ratio are better predictors of some risks.
  • Thresholds can differ by ethnicity, and children, teenagers, older adults and pregnant women need different references.

Using the number wisely

Treat BMI as a screening starting point. Combine it with blood pressure, blood tests, fitness, diet and family history, and talk to a doctor or dietitian before making health decisions. This tool is informational and not medical advice.

Frequently Asked Questions

What is BMI and how is it calculated?
BMI (Body Mass Index) is a number derived from your weight and height. The metric formula is: BMI = weight in kilograms divided by height in meters squared. For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9. It is used as a general screening indicator for weight categories.
What are the BMI categories?
The World Health Organization defines four adult BMI categories: Underweight (below 18.5), Normal weight (18.5 to 24.9), Overweight (25.0 to 29.9), and Obese (30.0 and above). These ranges apply to adults aged 18 and older. Children and teenagers use age- and sex-specific charts.
Is BMI accurate for everyone?
BMI is a useful population-level screening tool, but it has limitations for individuals. It does not distinguish between fat mass and muscle mass, so athletes with high muscle mass may be classified as overweight even when they are healthy. It also does not account for fat distribution, age, sex, or ethnicity. Always interpret BMI alongside other health indicators.
How do I calculate BMI with imperial units (pounds and inches)?
The imperial formula is: BMI = 703 × weight (lb) ÷ height² (in). For example, a person weighing 154 lb and standing 69 inches tall has a BMI of 703 × 154 ÷ (69 × 69) = 22.7. Select 'Imperial' on this calculator and it will apply the correct formula automatically.
What BMI is considered healthy?
A BMI between 18.5 and 24.9 is generally considered the normal or healthy weight range for adults. However, 'healthy weight' is a complex concept. Factors such as fitness level, diet, blood pressure, and family history are equally or more important than BMI alone. Use BMI as a starting point for a conversation with your doctor, not as a definitive health verdict.