BMI Calculator

A 5'9" person weighing 160 lbs has a BMI of 23.6, which falls in the "Normal Weight" range. Enter your measurements below for your personalized result.

Supports both imperial and metric units. See your BMI category and healthy weight range instantly.

Calculator

Unit System

Weight (lbs)

Height (feet)

Height (inches)

Your BMI

23.6

How BMI Is Calculated

BMI = Weight (kg) ÷ Height (m)²

Body Mass Index is a simple mathematical formula that relates your weight to your height. Developed by Belgian mathematician Adolphe Quetelet in the 1830s, it was originally designed for population-level health studies, not individual health assessments. Despite its limitations, BMI remains widely used because it's quick, free, and requires no special equipment.

The WHO BMI categories are: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obese Class I (30–34.9), Obese Class II (35–39.9), and Obese Class III (40+). These thresholds were established based on mortality and disease risk data from large population studies.

BMI is a useful starting point, but for a complete picture of your health, combine it with our Calorie Calculator to understand your energy needs, and our Water Intake Calculator for daily hydration goals. If you're focused on fitness, your sleep quality plays a major role in metabolism and weight management.

Calculators & Reference Tools

BMI Reference Chart

Height	Weight	BMI	Category
5'4" (163 cm)	125 lbs (57 kg)	21.5	Normal
5'9" (175 cm)	160 lbs (73 kg)	23.6	Normal
5'10" (178 cm)	195 lbs (88 kg)	28.0	Overweight
6'0" (183 cm)	220 lbs (100 kg)	29.8	Overweight

Worked Example

For a person who is 5'10" and weighs 180 lbs:

Height in inches: 5 × 12 + 10 = 70 inches
BMI = (180 × 703) ÷ (70 × 70)
= 126,540 ÷ 4,900
= 25.8 (Overweight)

At 5'10", a healthy BMI (18.5–24.9) corresponds to a weight range of approximately 129–174 lbs. This person would need to lose about 6 lbs to reach the upper end of the normal range.

BMI Limitations You Should Know

Doesn't measure body fat directly. Two people with the same BMI can have very different body fat percentages.
Overestimates fat in muscular people. Athletes and weightlifters often have "overweight" BMIs despite low body fat.
Underestimates fat in older adults. Muscle mass decreases with age, so an older person may have a normal BMI but high body fat.
Doesn't account for fat distribution. Visceral fat (belly fat) is more dangerous than subcutaneous fat, but BMI can't tell the difference.
Varies by ethnicity. Some populations have higher health risks at lower BMI thresholds. Asian populations, for example, may have elevated risks above BMI 23.

Frequently Asked Questions

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is considered "normal weight" by the WHO and CDC. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is classified as obese. However, BMI doesn't account for muscle mass, bone density, or body composition.

Is BMI accurate for athletes?

No. BMI can overestimate body fat in athletes and muscular individuals because it doesn't distinguish between muscle and fat. A bodybuilder with 8% body fat could have a "obese" BMI. For athletes, body fat percentage or waist-to-hip ratio are better metrics.

How is BMI calculated?

BMI = weight in kilograms ÷ (height in meters)². In imperial units: BMI = (weight in pounds × 703) ÷ (height in inches)². It's a simple ratio of weight to height squared.

Does BMI apply to children?

Children and teens use BMI-for-age percentiles instead of fixed ranges because body composition changes as they grow. A pediatrician can plot your child's BMI on age-appropriate growth charts.

What are the limitations of BMI?

BMI doesn't account for muscle mass, bone density, age, sex, ethnicity, or fat distribution. Belly fat (visceral fat) is more dangerous than fat stored elsewhere, but BMI can't tell the difference. It's a screening tool, not a diagnostic one.