Health and Fitness
BMI Calculator
Calculate your Body Mass Index instantly and see exactly where you stand on the health scale with an interactive visual gauge.
centimeters (cm)
kilograms (kg)
<18.5
18.5–24.9
25–29.9
30+
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Healthy BMI Range
18.5 – 24.9
Your Status
—
Healthy Weight For You
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BMI Prime
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📋 How To Use This BMI Calculator
1
Choose your unit system. Select Metric (cm/kg) if you use the international system, or Imperial (feet/lbs) if you use the US system.
2
Enter your height. In metric mode, enter your height in centimeters. In imperial mode, enter feet and remaining inches separately.
3
Enter your weight. Enter your current body weight in kilograms (metric) or pounds (imperial).
4
Click Calculate. Your BMI score appears instantly on the animated gauge, with your category, healthy weight range, and BMI Prime shown below.
⚙️ How BMI Is Calculated
The Formula
BMI = weight (kg) ÷ height² (m²). For imperial: BMI = 703 × weight (lbs) ÷ height² (inches²).
BMI Prime
BMI Prime is your BMI divided by 25 (the upper limit of normal). A value of 1.0 means you’re exactly at the upper boundary of normal weight.
Healthy Weight Range
Your personal healthy weight range is calculated by applying BMI values of 18.5 and 24.9 to your specific height.
The Gauge
The gauge spans BMI 10 to 45. The needle animates to your exact position, color-coded across the four WHO-defined categories.
| Category | BMI Range | Status |
|---|---|---|
| Underweight | Below 18.5 | Below healthy range |
| Normal Weight | 18.5 – 24.9 | Healthy range ✓ |
| Overweight | 25.0 – 29.9 | Above healthy range |
| Obese | 30.0 and above | Well above healthy range |
❓ Frequently Asked Questions
A BMI between 18.5 and 24.9 is considered normal or healthy weight for most adults. A score below 18.5 indicates underweight, 25–29.9 indicates overweight, and 30 or above indicates obesity. Keep in mind that BMI is a screening tool, not a definitive measure of health.
BMI is a useful general screening tool, but it does not account for muscle mass, bone density, age, sex, or fat distribution. Athletes with high muscle mass may have a high BMI without being unhealthy. For a complete health assessment, consult a healthcare professional.
Yes. For adults aged 20 and over, BMI categories are fixed. For children and teens (aged 2–19), BMI is interpreted using age and sex-specific percentile charts because body fat naturally changes as children grow. This calculator is designed for adults.
BMI Prime is your BMI divided by 25. It tells you how far you are from the upper boundary of normal weight. A BMI Prime of 1.0 means you’re exactly at that boundary. Below 1.0 is normal or underweight, above 1.0 means overweight or obese. It’s a quick way to see your ratio at a glance.
There’s no strict rule, but checking once a month is generally a good habit if you’re monitoring your weight for health or fitness goals. Daily fluctuations in weight are normal due to water retention, meals, and activity, so weekly or monthly checks give a more accurate picture.
Research shows that a high BMI is associated with increased risk of heart disease, type 2 diabetes, high blood pressure, and certain cancers. However, BMI alone is not a diagnosis. Other factors like waist circumference, blood pressure, cholesterol, and lifestyle habits are equally important in assessing overall health risk.
Yes, this BMI calculator is completely free to use with no sign-up, no account, and no limits. You can use it as many times as you like.
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