Free BMI Calculator Online Tool - 100% Free & No Sign Up | yoyotools

What is the BMI Calculator?

The BMI Calculator is a free online tool that calculates your Body Mass Index (BMI) — a widely used measure of body fat based on your height and weight. BMI helps you understand whether your weight falls in the underweight, normal, overweight, or obese range. It works in both metric (cm, kg) and imperial (inches, lbs) units, runs entirely in your browser, and never stores your data.

How BMI is Calculated

BMI uses a simple formula. Metric: BMI = weight (kg) ÷ height (m)². Imperial: BMI = (weight (lbs) ÷ height (in)²) × 703. For example, a person who is 170 cm tall and weighs 65 kg has a BMI of about 22.5, which falls in the normal weight range.

BMI Categories

• Underweight: BMI below 18.5 • Normal weight: BMI 18.5 to 24.9 • Overweight: BMI 25 to 29.9 • Obese: BMI 30 and above

How to Use

1. Choose metric or imperial units 2. Enter your height 3. Enter your weight 4. View your BMI and weight category instantly

Frequently Asked Questions

Is BMI accurate for everyone?

BMI is a useful general screening tool but does not directly measure body fat. It may overestimate body fat in athletes with high muscle mass and underestimate it in older adults. Consult a healthcare provider for a full assessment.

Is my data safe?

Yes. All calculations happen locally in your browser. Your height and weight are never uploaded or stored.

What is a healthy BMI?

For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range.

BMI Calculator

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