BMI Calculator
Height
| Category | BMI | Description |
|---|---|---|
| Underweight | < 18.5 | May indicate insufficient nutrition |
| Healthy weight | 18.5 – 24.9 | Lowest health risk range |
| Overweight | 25.0 – 29.9 | Increased risk of chronic disease |
| Obesity class I | 30.0 – 34.9 | Moderate risk; lifestyle change advised |
| Obesity class II | 35.0 – 39.9 | High risk; medical guidance recommended |
| Obesity class III | ≥ 40.0 | Very high risk; clinical care advised |
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How to use
- 1 Choose units: metric (cm and kg) or US (feet/inches and pounds).
- 2 Enter your height. For US units, enter feet and inches separately.
- 3 Enter your weight. Use your most recent measurement, ideally first thing in the morning.
- 4 Click Calculate to see your BMI value, the CDC weight category, and a healthy reference weight for your height.
- 5 Discuss the result with a healthcare provider — BMI is a screening tool, not a diagnosis. Use waist circumference and other measurements for a fuller picture.
About BMI Calculator
FAQ
Q What is a healthy BMI for women over 50?
The CDC uses the same healthy BMI range — 18.5 to 24.9 — for adult women regardless of age. However, some research suggests that women over 65 may have lower mortality risk in the 25–27 range due to muscle and bone preservation. Talk to your doctor about whether the standard cutoffs apply to you.
Q Is BMI 28 considered overweight or obese?
A BMI of 28 falls in the overweight category (25.0–29.9), not obese. Obesity begins at BMI 30. According to the CDC, people in the overweight range face an elevated risk of type 2 diabetes, hypertension, and heart disease, but the risk is generally lower than in the obesity classes.
Q How do I calculate BMI in pounds and inches without converting to metric?
Use the US formula: BMI = (weight in lb / height in in²) × 703. For example, a person 5'8" (68 in) and 160 lb has a BMI of (160 / 4624) × 703 = 24.3 — in the healthy range. This calculator handles both unit systems automatically.
Q Why is BMI different for Asian American adults?
The WHO and several Asian-Pacific health organizations recommend lower BMI cutoffs (overweight at 23, obese at 27.5) for people of Asian descent because cardiovascular and diabetes risk rises at lower BMI values in this population. The standard CDC cutoffs are still used in US clinical guidelines.
Q Can BMI be wrong if I'm muscular?
Yes. BMI does not distinguish fat from muscle, so highly muscular adults — bodybuilders, NFL linemen, certain CrossFit athletes — frequently score in the overweight or obese range despite low body fat. The CDC recommends combining BMI with waist circumference, body fat percentage, or DEXA scans for athletes.
Q What waist size is unhealthy for men and women?
The NHLBI considers a waist circumference over 40 inches (102 cm) for men or over 35 inches (88 cm) for non-pregnant women as a risk factor for type 2 diabetes, high blood pressure, and heart disease — independent of BMI. Combine waist measurement with BMI for a fuller picture.
Q How much weight do I need to lose to drop one BMI class?
A 5–10% reduction in body weight typically moves most adults down one category and produces clinically meaningful improvements in blood pressure, glucose, and lipids. For a 200 lb adult, that's 10–20 lb. The CDC recommends a target of 1–2 lb per week through diet and exercise.
Q Should pregnant women use this BMI calculator?
No. The CDC and ACOG do not apply standard adult BMI categories to pregnant women. Pre-pregnancy BMI is used to set healthy gestational weight gain targets per the Institute of Medicine, but during pregnancy the BMI value itself loses meaning as the body composition changes substantially.
Official resources
CDC — Adult BMI Calculator
Official US CDC adult BMI calculator and category definitions for ages 20 and older.
NHLBI / NIH — Calculate Your BMI
National Heart, Lung, and Blood Institute BMI tool with classification and waist-circumference guidance.
CDC — About Body Mass Index (BMI)
CDC explanation of how BMI is calculated, what it measures, and its limitations.
WHO — BMI Classification
World Health Organization BMI classification reference, including Asian-Pacific cutoffs.