BMI Calculator

Calculate your Body Mass Index instantly. Works with imperial (lbs, ft/in) and metric (kg, cm). Results based on CDC adult BMI guidelines.

Calculate Your BMI

ft
in
lbs

BMI Categories (CDC)

Under 18.518.5–24.925–29.930+
UnderweightBelow 18.5
Normal Weight ✓18.5 – 24.9
Overweight25.0 – 29.9
Obese30.0 and above

Related Health Tools

How to Use the BMI Calculator

  1. 1Select Imperial (lbs, feet/inches) or Metric (kg, cm).
  2. 2Enter your height and weight.
  3. 3Click Calculate BMI to see your result and category instantly.

What Is BMI?

Body Mass Index (BMI) is a numerical value calculated from a person's height and weight. It provides a simple screening tool to categorize adults into underweight, normal weight, overweight, or obese ranges. The CDC and World Health Organization use BMI as a cost-effective, non-invasive tool for population-level health monitoring.

BMI Formula

Imperial: BMI = (weight in lbs × 703) ÷ (height in inches)²

Metric: BMI = weight in kg ÷ (height in meters)²

Limitations of BMI

BMI does not distinguish between muscle and fat mass. Athletes and highly muscular individuals may score as "overweight" despite having very low body fat. BMI also doesn't account for fat distribution — belly fat (visceral fat) poses greater health risks than fat stored elsewhere. For a complete picture, consider also measuring waist circumference and body fat percentage.

Healthy Weight Range by Height

To be in the "Normal Weight" BMI range (18.5–24.9), here are approximate healthy weight ranges for common heights:

  • 5'4" (64 in): 108–145 lbs
  • 5'6" (66 in): 115–154 lbs
  • 5'9" (69 in): 125–168 lbs
  • 5'11" (71 in): 132–178 lbs
  • 6'0" (72 in): 136–183 lbs
  • 6'2" (74 in): 144–194 lbs

How to Calculate BMI (Formula and Example)

Body mass index compares your weight with your height. In US units the formula is BMI = weight in pounds × 703 ÷ (height in inches)². In metric units it is weight in kilograms ÷ (height in meters)².

For example, a person who is 5 feet 9 inches (69 inches) and weighs 170 pounds has a BMI of 170 × 703 ÷ 69² = 119,510 ÷ 4,761 = 25.1, which falls at the lower end of the overweight range. The same person at 160 pounds would have a BMI of about 23.6, in the healthy range.

BMI Categories for Adults

The CDC uses these standard categories for adults aged 20 and older: below 18.5 is underweight; 18.5 to 24.9 is a healthy weight; 25.0 to 29.9 is overweight; and 30.0 or higher is obesity. Obesity is often split further into class 1 (30.0 to 34.9), class 2 (35.0 to 39.9), and class 3 (40.0 and above). These categories are the same for men and women. For children and teens, BMI is interpreted using age- and sex-specific percentiles instead of fixed cutoffs.

What BMI Does Not Tell You

BMI is a quick screening number, not a diagnosis. It cannot tell muscle from fat, so a muscular athlete can land in the overweight range with little body fat. It also does not show where fat is stored, and it can read differently for older adults, pregnant women, and some ethnic groups. Waist circumference, blood pressure, blood sugar, cholesterol, family history, and activity level all matter for health. If your BMI is outside the healthy range, or you are concerned about your weight, talk with a doctor or registered dietitian about what makes sense for you.

Prepared by the ProCalcTools editorial team and last reviewed in October 2026. This page is for general information and is not financial, tax, or medical advice.

Frequently Asked Questions

A BMI of 18.5 to 24.9 is considered normal and healthy for adults by the CDC. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
BMI is a general screening tool and not a diagnostic measure. It correlates moderately well with body fat in the general population, but can be inaccurate for athletes, elderly individuals, pregnant women, and some ethnic groups. Always pair BMI with a professional health assessment.
Yes, according to standard BMI classifications, a score of 25.0 or above falls into the "overweight" category. However, this is a general guideline. A BMI of 25 in a fit, muscular person may not indicate excess body fat. Consult your doctor for a personalized assessment.
According to CDC data, the average BMI for American adults is approximately 29.7 for women and 29.1 for men — placing the average American in the "overweight" category (25–29.9). About 42% of US adults are classified as obese (BMI ≥ 30).
To lower your BMI, you need to reduce body fat through a caloric deficit (consuming fewer calories than you burn). A combination of a balanced, moderate-calorie diet and regular physical activity is the most sustainable approach. Even a 5–10% reduction in body weight can significantly improve health markers.