BMI Calculator

Body Mass Index (BMI) is a simple screening measure that uses your height and weight to estimate whether you are underweight, normal weight, overweight, or obese. While BMI does not measure body fat directly and has known limitations, it remains one of the most widely used health indicators worldwide.

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Unit System

Height

Weight (kg)

Body Composition Tools

Smart scales, body fat calipers, and measuring tapes for tracking your body composition beyond BMI.

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Frequently Asked Questions

What is BMI?

Body Mass Index (BMI) is a numerical value calculated from your weight and height. The formula is weight (kg) divided by height (m) squared. It is used as a screening tool to identify possible weight problems in adults.

What are the BMI categories?

Underweight: below 18.5. Normal weight: 18.5 to 24.9. Overweight: 25 to 29.9. Obese: 30 and above. These ranges apply to most adults but may not be accurate for athletes, pregnant women, or the elderly.

Is BMI accurate?

BMI is a rough screening tool and does not distinguish between muscle mass and body fat. A muscular athlete may have a high BMI but low body fat. For a more complete picture, consider combining BMI with waist-to-height ratio, body fat percentage, or a DEXA scan.

How often should I check my BMI?

Checking BMI once every few months is sufficient for most people tracking general trends. More important than any single reading is the direction of change over time. Always pair BMI with other health markers for the full picture.

More Body Composition Tools

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Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method. Measure your neck, waist, and hips with a tape measure to get an accurate body fat estimate.

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Ideal Weight Calculator

Calculate your ideal body weight using four established medical formulas: Devine, Robinson, Miller, and Hamwi. Compare results and find a healthy weight range for your height.

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Lean Body Mass Calculator

Calculate your lean body mass (fat-free mass) using the Boer, James, and Hume formulas. Understand how much of your body weight is muscle, bone, and organs versus fat.

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Waist-to-Hip Ratio

Calculate your waist-to-hip ratio (WHR) and assess your health risk level. WHR is a simple, evidence-based screening tool for cardiovascular and metabolic disease risk.

Related Tools

📏

Body Fat Calculator

Estimate your body fat percentage using the US Navy circumference method. Measure your neck, waist, and hips with a tape measure to get an accurate body fat estimate.

🎯

Ideal Weight Calculator

Calculate your ideal body weight using four established medical formulas: Devine, Robinson, Miller, and Hamwi. Compare results and find a healthy weight range for your height.

📐

Waist-to-Height Ratio

Calculate your waist-to-height ratio — a simple, powerful predictor of cardiometabolic risk. Compare your result to health guidelines and track your progress.

📐

Waist-to-Hip Ratio

Calculate your waist-to-hip ratio (WHR) and assess your health risk level. WHR is a simple, evidence-based screening tool for cardiovascular and metabolic disease risk.

BMI Calculator & Body Mass Index: What It Measures and Limitations

BMI Calculator: What Your Number Actually Means

Body Fat Percentage Calculator: Methods and Meaning