Health & Fitness Tools

BMI Calculator

Q: What is a normal BMI score?

For most adults, a BMI between 18.5 and 24.9 falls in the "normal weight" range. Below 18.5 is classified as underweight, 25 to 29.9 as overweight, and 30 or above as obese. These ranges are general population screening categories, not a diagnosis.

Q: How is BMI calculated?

BMI uses the formula BMI = [Weight (lbs) ÷ Height (in)²] × 703, or in metric units BMI = Weight (kg) ÷ Height (m)². For example, a person who is 5'8" (68 inches) and weighs 160 lbs has a BMI of (160 ÷ 68²) × 703 = 24.3.

Q: Is BMI an accurate measure of health for everyone?

No. BMI does not distinguish between muscle and fat mass, so athletes and highly muscular individuals can show a high BMI without excess body fat. It also does not account for age, sex, bone density, or fat distribution. BMI is a quick population-level screening tool, not a diagnostic measurement of individual health.

Q: What other measurements should I consider alongside BMI?

Waist circumference, waist-to-hip ratio, and body fat percentage give a more complete picture of body composition than BMI alone. If you have concerns about your weight or health risk, discuss these measurements with a doctor or registered dietitian rather than relying on BMI in isolation.

Free BMI calculator using height and weight. Get your Body Mass Index, weight category, and healthy-range context based on WHO adult screening standards.

Interactive Calculator

1. Provide Details

Weight (lbs)

lbs

Height (Feet)

Height (Inches)

2. Output Results

BMI Score24.33

Weight CategoryNormal Weight (18.5 - 24.9)

How to Calculate: Formula & Steps

Computes the standard weight-to-height ratio index.

Formula Used:BMI = [Weight (lbs) ÷ Height (in)²] × 703

Step-by-Step Calculation Example

Height 5ft 8in, weight 160 lbs yields a BMI score of 24.3 (Normal).

Inputs and Assumptions

Enter values that match your project or situation. The calculator uses the following fields and defaults; update them before relying on the estimate.

Weight (lbs): Default: 160 lbs
Height (Feet): Default: 5 ft
Height (Inches): Default: 8 in

Common Mistakes to Avoid

Relying on BMI when having high muscle density (muscle weighs more than fat).

Practical Use Cases

Weight screening
Fitness baseline setup

Expert Tips

Combine with waist circumference measurements for better body profile assessments.

Body Mass Index (BMI) Clinical Categories & Calculation Formulas

Body Mass Index (BMI) is an anthropometric screening metric established by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) to categorize adult weight status relative to height.

Imperial Formula (Pounds & Inches)

BMI = [Weight (lbs) ÷ Height (in)²] × 703

For 160 lbs at 5'8" (68 in): (160 ÷ 4,624) × 703 = 24.32 (Normal).

Metric Formula (Kg & Meters)

BMI = Weight (kg) ÷ Height (m)²

For 72.5 kg at 1.73 m: 72.5 ÷ (1.73 × 1.73) = 24.22 (Normal).

WHO Standard Adult BMI Classifications

Category	BMI Range (kg/m²)	Associated Health Risk Profile
Underweight	< 18.5	Increased risk for nutritional deficiency & osteoporosis.
Normal Weight	18.5 – 24.9	Lowest statistical risk for cardiovascular disease.
Overweight	25.0 – 29.9	Moderate risk for hypertension and pre-diabetes.
Obesity (Class I–III)	≥ 30.0	High risk for type 2 diabetes, stroke, and sleep apnea.

Disclaimer

This calculation tool is provided for educational and informational estimation purposes only. Results are based on mathematical formulas and user-supplied parameters. They do not constitute formal underwriting, financial, tax, engineering, or legal determinations.

Frequently Asked Questions About BMI Calculator

What is a normal BMI score?

For most adults, a BMI between 18.5 and 24.9 falls in the "normal weight" range. Below 18.5 is classified as underweight, 25 to 29.9 as overweight, and 30 or above as obese. These ranges are general population screening categories, not a diagnosis.

How is BMI calculated?

BMI uses the formula BMI = [Weight (lbs) ÷ Height (in)²] × 703, or in metric units BMI = Weight (kg) ÷ Height (m)². For example, a person who is 5'8" (68 inches) and weighs 160 lbs has a BMI of (160 ÷ 68²) × 703 = 24.3.

Is BMI an accurate measure of health for everyone?

No. BMI does not distinguish between muscle and fat mass, so athletes and highly muscular individuals can show a high BMI without excess body fat. It also does not account for age, sex, bone density, or fat distribution. BMI is a quick population-level screening tool, not a diagnostic measurement of individual health.

What other measurements should I consider alongside BMI?

Waist circumference, waist-to-hip ratio, and body fat percentage give a more complete picture of body composition than BMI alone. If you have concerns about your weight or health risk, discuss these measurements with a doctor or registered dietitian rather than relying on BMI in isolation.

Editorial contact: Orion Mercer

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