Free Online BMI Calculator
Calculate your Body Mass Index (BMI) instantly. Enter your height and weight in metric or imperial units to check if you're at a healthy weight. Free, no signup required.
Important: BMI is a screening tool, not a diagnostic measure. It doesn't account for muscle mass, bone density, age, or gender. Athletes may have a high BMI due to muscle mass. Always consult a healthcare provider for a comprehensive health assessment.
Visual BMI Scale
See where you fall on the BMI chart
Metric & Imperial
Use kg/cm or lb/ft units
Health Guidance
Personalized recommendations
What is BMI (Body Mass Index)?
Body Mass Index (BMI) is a simple measure that uses your height and weight to estimate if you're at a healthy weight. It's widely used by healthcare providers as a quick screening tool to identify potential weight-related health issues.
How to Calculate BMI
The BMI formula divides your weight by your height squared. In metric units: BMI = weight (kg) / height (m)². In imperial units: BMI = (weight (lb) × 703) / height (in)². Our calculator does this automatically - just enter your measurements.
BMI Categories Explained
Underweight (BMI < 18.5)
May indicate nutritional deficiency or other health issues. Consider consulting a healthcare provider.
Normal Weight (BMI 18.5-24.9)
Generally associated with lower risk of weight-related health problems. Maintain with balanced diet and exercise.
Overweight (BMI 25-29.9)
May increase risk of heart disease, diabetes, and other conditions. Lifestyle changes can help.
Obese (BMI 30+)
Higher risk of serious health conditions. Medical guidance is recommended for safe weight management.
BMI Limitations
While BMI is a useful screening tool, it has limitations. It doesn't distinguish between muscle and fat, so athletes may have a "high" BMI despite being healthy. It also doesn't account for age, gender, ethnicity, or where fat is stored on the body. For a complete health assessment, consult a healthcare professional.
Frequently Asked Questions
What is a healthy BMI?
A healthy BMI is between 18.5 and 24.9. This range is associated with lower risk of weight-related health problems like heart disease, diabetes, and high blood pressure.
How do I calculate my BMI?
BMI = weight (kg) / height (m)². For example, if you weigh 70 kg and are 1.75 m tall: 70 / (1.75 × 1.75) = 22.9. Our calculator does this instantly for you.
Is BMI accurate for everyone?
BMI is a screening tool, not a diagnostic measure. It may not be accurate for athletes, elderly people, or those with more muscle mass. Always consult a healthcare provider for a complete assessment.
What's my ideal weight for my height?
Our calculator shows your healthy weight range based on BMI 18.5-24.9. For a 170 cm tall person, the healthy weight range is approximately 53-72 kg.