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Free Online BMI Calculator

Calculate your Body Mass Index instantly. Supports metric (kg/cm) and imperial (lbs/ft) units. Includes BMI chart, health categories, ideal weight range and health tips.

Metric & Imperial BMI Scale Visualizer Ideal Weight Range Health Tips Instant Results

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⚖️ Enter Your Measurements

kg
cm
years

Press Enter in any field to calculate

Your BMI
Underweight
<18.5
Normal
18.5–24.9
Overweight
25–29.9
Obese
>30
BMI Score
Ideal Weight Range
Weight to Lose/Gain
CategoryBMI RangeRisk
Underweight< 18.5Moderate
Normal Weight18.5 – 24.9Low
Overweight25.0 – 29.9Moderate
Obese Class I30.0 – 34.9High
Obese Class II+≥ 35.0Very High

How to Use the Toolzey BMI Calculator

Calculating your BMI takes less than 30 seconds:

  1. Select your unit system — Choose Metric (kg/cm) or Imperial (lbs/ft/in) using the toggle above.
  2. Enter your weight and height — Type your measurements into the fields. You can also optionally add age and gender for additional context.
  3. Click "Calculate My BMI" — Your BMI score, category, ideal weight range and visual scale appear instantly.

What is BMI and What Does It Mean?

BMI (Body Mass Index) is a numerical value calculated from your height and weight. It provides a simple, quick screening measure for categorising weight status. The WHO defines four main BMI categories for adults:

  • Underweight (BMI < 18.5): May indicate malnutrition, eating disorders or other health issues. Consult a doctor.
  • Normal weight (18.5–24.9): Associated with the lowest health risks for most adults. Aim to maintain this range.
  • Overweight (25.0–29.9): Modestly increased risk of cardiovascular disease, type 2 diabetes and other conditions.
  • Obese (≥ 30.0): Significantly increased risk of serious health conditions. Medical guidance is recommended.

Important note: BMI is a population-level screening tool. It does not account for muscle mass, bone density, age, ethnicity, or body fat distribution. Athletes and bodybuilders may show a "high" BMI while being in excellent health. Always consult a qualified healthcare professional for a complete health assessment.

Frequently Asked Questions

According to the World Health Organization (WHO), a healthy BMI for adults is between 18.5 and 24.9. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese. However, BMI is a screening tool, not a diagnostic one.
No, BMI is less accurate for athletes and bodybuilders because it cannot distinguish between muscle mass and fat mass. A heavily muscled person may have a "high" BMI but very low body fat. More accurate measures include body fat percentage (DEXA scan) or waist-to-height ratio.
BMI = weight (kg) ÷ height² (m²). For example, a person weighing 70kg at 175cm has a BMI of 70 ÷ (1.75 × 1.75) = 22.9. For imperial: BMI = (weight in lbs × 703) ÷ (height in inches)².
BMI calculation for children and teens uses age and sex-specific percentile charts, not the same fixed categories as adults. Our calculator is designed for adults (18+). For children, consult a paediatrician.
Yes. Research suggests that people of Asian descent may have higher health risks at lower BMI values. Some health organisations recommend lower BMI thresholds for Asian populations (e.g., overweight at BMI ≥ 23 instead of ≥ 25).