How is BMI calculated?

BMI is your weight divided by the square of your height. In US units, multiply your weight in pounds by 703 and divide by your height in inches squared. In metric, divide weight in kilograms by height in meters squared.

What is a healthy BMI?

For adults 20 and older, the CDC and the NIH call a BMI from 18.5 to 24.9 a healthy weight. Below 18.5 is underweight, 25.0 to 29.9 is overweight and 30.0 or more is obesity. These are screening categories, not a diagnosis.

Is BMI accurate for athletes or older adults?

Not always. BMI does not distinguish muscle from fat, so very muscular people can have a high BMI without excess body fat, and older adults who have lost muscle can have a normal BMI with a high percentage of body fat. Waist size and other measurements add useful information.

Can I use this calculator for a child or teenager?

No. For people under 20, BMI is compared with percentiles for age and sex on CDC growth charts instead of the adult cutoffs. A pediatrician can interpret a child's BMI correctly.

BMI Prime is your BMI divided by 25, the upper limit of the healthy range for adults in the United States. A value below 1.0 means your BMI is under the overweight cutoff, and a value of 1.2 means your BMI is 20% above it.

Does this replace medical advice?

No. BMI is one screening number and does not consider your health history, body composition, age or fitness. Talk to a doctor or registered dietitian before you make changes to your diet or exercise based on any calculator.

💪 Health & Fitness

BMI Calculator · Body Mass Index in Feet, Inches and Pounds

Body mass index, or BMI, is a number that compares your weight with your height. Doctors and public health agencies use it as a quick screening tool because it is easy to calculate and it correlates with health risks at the population level. This calculator works in feet, inches and pounds, and also accepts centimeters and kilograms.

Enter your height and weight and you get your BMI, the adult category it falls in and the healthy weight range for your height, in pounds and kilograms, together with how far you are from that range. The categories used in the United States are underweight below 18.5, healthy weight from 18.5 to 24.9, overweight from 25.0 to 29.9 and obesity from 30.0, which is divided into three classes.

BMI has real limits. It does not measure body fat, muscle or where the weight is carried, so a muscular athlete can have a high BMI without excess fat and an older adult can have a normal BMI with little muscle. For people under 20 the adult cutoffs do not apply: BMI is compared with percentiles for age and sex. Treat the result as one piece of information and talk to a health professional about your own situation. This tool is educational and is not medical advice.

Detailed Breakdown

7 metrics

PRIMARY RESULT

23.6

Your BMI

BMI Category

Healthy weight

Healthy Weight Range for Your Height

125.3 lb to 168.6 lb (56.8 kg to 76.5 kg)

Compared With the Healthy Range

You are in the healthy range

BMI Prime (BMI ÷ 25)

0.95

Your Height

5 ft 9 in (175.3 cm)

Your Weight

160.0 lb (72.6 kg)

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When to Use This Calculator

Everyday financial situations where this tool gives you fast, accurate clarity:

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Check Your BMI

Find your body mass index from your height and weight in feet, inches and pounds.

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See the Healthy Range

Find the weight range that matches a BMI of 18.5 to 24.9 for your height.

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Track Over Time

Recalculate as your weight changes to see how far you are from the healthy range.

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Prepare for a Checkup

Know your number before you talk to your doctor about weight and health risks.

Calculation Formula

Standard Method

BMI = 703 × weight in pounds ÷ (height in inches)² BMI = weight in kilograms ÷ (height in meters)² Adult categories (CDC and NIH): Below 18.5: underweight · 18.5 to 24.9: healthy weight · 25.0 to 29.9: overweight · 30.0 to 34.9: obesity class 1 · 35.0 to 39.9: obesity class 2 · 40.0 and above: obesity class 3 Healthy weight range for your height = BMI 18.5 to 24.9 × (height in inches)² ÷ 703. BMI Prime = BMI ÷ 25, so a value above 1.0 is above the overweight cutoff. When both centimeters and kilograms are entered they replace the feet, inches and pounds. Heights are limited to 3 to 8 feet and weights to 20 to 1,000 pounds.

Benchmark Example:

A person who is 5 ft 9 in (69 inches) tall and weighs 160 lb: • BMI = 703 × 160 ÷ 69² = 112,480 ÷ 4,761 = 23.6 • Category: healthy weight • Healthy range for 69 inches: 18.5 × 4,761 ÷ 703 = 125.3 lb up to 24.9 × 4,761 ÷ 703 = 168.6 lb • BMI Prime: 23.6 ÷ 25 = 0.95 At 170 lb the same person has a BMI of 25.1, just above the overweight cutoff and about 1.4 lb over the top of the healthy range. At 110 lb the BMI is 16.2, underweight, and about 15.3 lb below the bottom of the range.

Frequently Asked Questions

6 answers

Applicable Laws & Regulatory Standards

Centers for Disease Control and Prevention & National Institutes of Health

Official Legal Reference

CDC — About Adult BMI (categories for adults age 20 and older)

Defines the adult categories used in the United States: underweight below 18.5, healthy weight 18.5 to 24.9, overweight 25.0 to 29.9 and obesity 30.0 and above.

NIH / NHLBI — Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (1998)

Established the BMI cutoffs of 25 and 30 and the obesity classes used by U.S. clinicians, and states that BMI is a screening tool to be interpreted along with other risk factors.

CDC — Clinical Growth Charts and BMI-for-age percentiles (ages 2 to 19)

For children and teens BMI is interpreted as a percentile for age and sex, not with the adult cutoffs, which is why this calculator flags ages under 20.

Legal citations and statutes are provided for consumer transparency, analytical validation, and educational reference under U.S. consumer financial regulations. This tool is not a substitute for formal legal, accounting, or tax counsel.

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