Free BMI Calculator for Men, Women & Teens (US Units & Metric)

Calculate your Body Mass Index (BMI) quickly and accurately using US units (pounds, feet, inches) or metric. Instantly view your BMI category, CDC-based healthy weight range, and get actionable health guidance. For children and teenagers (ages 2-19), results use age and gender-specific percentile logic.

Calculate Your BMI

Gender

For adults (20+), standard BMI categories are used. For ages 2-19, use BMI-for-age percentile charts. BMI does not directly measure body fat, muscle mass, or medical conditions.

Healthy weight range for your height-
Target insight-

BMI is a screening tool and does not directly measure body fat, muscle mass, or medical conditions.

BMI 0.0 Not calculated

Your BMI

0.0

-

What it means

Your personalized guidance will appear here.

Selected gender: Male. Adult BMI ranges are the same for men and women.

Age guidance: For adults (20+), standard BMI categories are used.

Input: -

Healthy weight range for your height-
Target insight-

BMI is a screening tool and does not directly measure body fat, muscle mass, or medical conditions.

How to Use This BMI Calculator

  1. Select your unit system: Metric (kg, cm) or US (lb, ft/in).
  2. Select your gender and enter age (2-120 years).
  3. Enter your current weight and height carefully.
  4. Click "Calculate BMI" to get instant result and meter position.
  5. Review "What it means", healthy weight range, and target insight.
  6. For ages 2-19, read percentile-based interpretation instead of adult ranges.
  7. Use "Reset/Clear" to start a new calculation.

BMI Categories (Adults)

BMI categories are standard ranges used for adult screening. They help estimate health risk, but they are not a full diagnosis.

Category BMI Range General Interpretation
Underweight < 18.5 Below healthy range
Normal weight 18.5 - 24.9 Healthy range for most adults
Overweight 25.0 - 29.9 Above healthy range
Obesity 30.0 and above Higher health risk range

Standard BMI Chart with Color Indicator

This chart shows the standard adult BMI ranges from 10 to 40+ and highlights each category with a color indicator.

10 18.5 25 30 40+
Underweight (< 18.5)
Normal (18.5 - 24.9)
Overweight (25.0 - 29.9)
Obesity (30.0+)

How BMI Is Calculated (Formulas)

Understanding how to calculate your BMI in lbs and inches (US units) or kg and meters (Metric) is simple. Our accurate BMI calculator uses these standard formulas:

US Formula (Pounds and Inches)

BMI = 703 x weight (lb) / [height (in)]^2

This is the standard formula used in the United States. Multiply your weight in pounds by 703, then divide by your height in inches squared.

Metric Formula (Kilograms and Meters)

BMI = weight (kg) / [height (m)]^2

Our free BMI checking tool automatically handles the complete math and unit conversion for you instantly.

What Is Body Mass Index (BMI) and Target Weight?

Body Mass Index (BMI) is a widely-used screening method that compares your weight to your height to estimate your total body fat. For adult men and women (age 20+), fixed BMI categories are applied identically. For children and teens (ages 2-19), your Body Mass Index must be evaluated using pediatric BMI-for-age percentile charts.

  • Adult BMI (Men & Women): Fixed ranges, where 18.5 to 24.9 indicates a healthy, normal range.
  • Pediatric BMI (Teens & Kids): Percentile-based interpretation that is highly specific to age and gender.
  • Purpose: A fast cardiovascular and metabolic risk screening tool, though it is not a direct body fat percentage test.

How This BMI Calculator Interprets Results

The calculator first computes BMI from your weight and height. Then it applies interpretation rules based on age.

  • Age 20+: standard adult categories (Underweight, Normal, Overweight, Obesity).
  • Ages 2-19: CDC BMI-for-age percentile logic using gender-specific LMS data.
  • BMI meter: pointer moves in real time to match your result zone.
  • Healthy range and target insight: shown from your entered height and result mode.

Why Use Our BMI Calculator?

  • Fast and clear: instant score, category, and meter view.
  • Adult and pediatric support: works for ages 2-120 with correct interpretation mode.
  • Dual units: Metric and US modes produce consistent results.
  • Actionable output: healthy range and target insight shown with result.
  • Printable report: export your current BMI result with notes.
  • User-focused design: mobile, tablet, and desktop-friendly layout.

Advanced Features

Real-Time Analog BMI Meter

The half-round analog meter updates instantly after each calculation and highlights your current result zone.

Pediatric Percentile Interpretation

For ages 2-19, this page uses BMI-for-age percentile logic instead of adult categories to provide age-appropriate interpretation.

Height-Based Healthy Range Guidance

Based on your entered height, the calculator shows a practical healthy range and a target insight to support planning.

Tips for Best BMI Tracking

  • Use consistent timing: track at the same time of day for better comparison.
  • Measure accurately: avoid rounded estimates for height and weight.
  • Review trends: monthly trend is more useful than one isolated value.
  • Pair with other markers: waist size, blood pressure, sleep, and activity matter.
  • For children: focus on percentile trend, not only one reading.

Privacy & Security

  • Local processing: BMI calculations run in your browser.
  • No account required: use the calculator without registration.
  • No medical record creation: this page is a quick self-check tool.
  • Secure page delivery: site is served over HTTPS.

Accuracy and Reliability

Calculation Standards

  • Uses standard BMI formulas for Metric and US units.
  • Adult category ranges align with common clinical screening cutoffs.
  • Ages 2-19 use percentile-based interpretation from age and gender inputs.

When to Verify with Professionals

  • Rapid unplanned weight change.
  • Chronic illness, pregnancy, or endocrine conditions.
  • Athletic or high-muscle body composition where BMI may overestimate risk.
  • Any treatment plan for weight gain or weight loss.

Common BMI Calculator Use Cases

  • General health screening at home.
  • Monthly progress checks during fitness plans.
  • Pre-consultation health summary before doctor visits.
  • Parent awareness of child growth trend using percentile logic.
  • Workplace wellness and preventive health tracking.

Important BMI Notes

  • BMI is screening, not diagnosis: it helps identify risk bands only.
  • Not body-fat percentage: fat, muscle, and bone mass are not directly measured.
  • Context matters: age, activity level, and medical history can change interpretation.
  • Use complete health data: include blood pressure, sugar, lipids, and waist measures.

Frequently Asked Questions (FAQ)

How do I calculate my BMI in lbs and inches?

To calculate your BMI using US units, multiply your weight in pounds by 703, then divide that number by your height in inches squared. Our free BMI calculator above does this automatically for you.

What is a good BMI for a 45-year-old woman or man?

For adults aged 20 and over, including a 45-year-old man or woman, a "good" or healthy BMI falls within the standard range of 18.5 to 24.9. The CDC uses the same categories for both adult men and women regardless of age.

Is this BMI calculator accurate?

Yes, it uses standard, validated mathematical formulas. However, the result's quality depends on accurate age, height, and weight input.

Why do children get percentile results instead of adult categories?

Because body composition changes rapidly with age and growth. For children and teens (ages 2-19), BMI must be interpreted against age and gender-specific CDC percentile charts.

Does BMI directly measure body fat?

No. BMI uses only weight and height. It is a rapid screening indicator for potential health risks, not a direct clinical body-fat test.

Which unit system should I use?

Use whichever is convenient (Metric kg/cm or US lbs/in). Both modes are converted internally and follow the exact same health interpretation logic.

Can athletes have high BMI but still be healthy?

Yes. Higher muscle mass can raise BMI without excess body fat. In such cases, additional body-composition measures (like waist-to-hip ratio or skinfold tests) are more useful.

Informational and Medical Disclaimer

Educational Tool Only

This BMI calculator is for informational and educational use. It helps with quick screening but does not replace medical diagnosis, treatment, or personalized clinical advice.

No Liability for Health Decisions

  • Always verify critical health decisions with qualified professionals.
  • Do not rely only on calculator output for diagnosis or treatment plans.
  • Any loss or risk from sole reliance on this tool remains user responsibility.

Professional Guidance Requirement

Weight-loss or weight-gain plans should be started and monitored under the supervision of a licensed doctor, dietitian, or qualified healthcare specialist.

Use with Clinical Context

For children, pregnancy, chronic disease, older adults, or athletes, BMI interpretation may require additional clinical context and specialist review.

Data Source Attribution

BMI-for-age percentile calculations for children and teens (ages 2–19) use LMS parameters sourced from the U.S. Centers for Disease Control and Prevention (CDC) — cdc.gov/growthcharts. This tool is not affiliated with, endorsed by, or sponsored by the CDC, HHS, or the U.S. Government. CDC data is used solely for statistical reference purposes.