The Centers for Disease Control and Prevention (CDC) is the official US federal health authority for BMI classification. If you have seen a BMI result from a doctor, health app, or insurance form in the United States, it almost certainly uses the CDC's official adult BMI categories.
This guide explains every CDC BMI category in detail — the exact ranges, what each classification means for your health, how BMI is calculated, and how CDC categories compare to UK NHS guidelines.
Check your CDC BMI category instantly with our free BMI Calculator — works in both imperial (lbs/inches) and metric (kg/cm).
What Is BMI According to the CDC?
The CDC defines Body Mass Index (BMI) as a measure of body weight relative to height. For adults 20 and older, BMI categories are based on a person's BMI regardless of age, sex, or race — unlike children and teenagers, who use age and sex-specific percentile charts.
Metric formula:
BMI = weight (kg) ÷ height (m)²
Imperial formula (used in the US):
BMI = (weight in lbs ÷ height in inches²) × 703
Important: The CDC describes BMI as a screening measure — not a diagnostic tool. A BMI outside the healthy range is a signal to discuss with a healthcare provider, not a diagnosis of disease or illness.
CDC BMI Categories for Adults — Official 2026 Ranges
BMI categories for adults aged 20 and older, based on WHO international standards:
| BMI Range | CDC Category |
|---|---|
| Less than 18.5 | Underweight |
| 18.5 to less than 25 | Healthy Weight |
| 25 to less than 30 | Overweight |
| 30 to less than 35 | Class 1 Obesity |
| 35 to less than 40 | Class 2 Obesity |
| 40 or greater | Class 3 Obesity (Severe Obesity) |
These thresholds are consistent with guidelines used by the NHS in the UK, making BMI a globally comparable measure.
CDC BMI Example — 5 Feet 9 Inches Tall
Weight and BMI categories for an adult who is 5 feet and 9 inches tall:
| Weight Range | BMI Range | CDC Category |
|---|---|---|
| 124 lbs or less | Less than 18.5 | Underweight |
| 125 – 168 lbs | 18.5 to less than 25 | Healthy Weight |
| 169 – 202 lbs | 25 to less than 30 | Overweight |
| 203 – 236 lbs | 30 to less than 35 | Class 1 Obesity |
| 237 – 270 lbs | 35 to less than 40 | Class 2 Obesity |
| 271 lbs or more | 40 or greater | Class 3 Obesity |
How to Calculate Your BMI — Step by Step
Imperial (pounds and inches) — used in the US
BMI = (weight in lbs ÷ height in inches²) × 703 Example — 180 lbs, 5'8" (68 inches): Step 1: 68 × 68 = 4,624 Step 2: 180 ÷ 4,624 = 0.03893 Step 3: 0.03893 × 703 = 27.4 Result: BMI = 27.4 → Overweight
Metric (kilograms and metres)
BMI = weight (kg) ÷ height (m)² Example — 82 kg, 1.73 m: Step 1: 1.73 × 1.73 = 2.9929 Step 2: 82 ÷ 2.9929 = 27.4 Result: BMI = 27.4 → Overweight
Rather than calculating manually, use our free BMI Calculator for an instant result in both imperial and metric.
CDC Healthy Weight Range — BMI 18.5 to 24.9
The CDC defines a healthy BMI as 18.5 to less than 25.0 for adults aged 20 and over. This range is associated with the lowest statistical risk of developing type 2 diabetes, cardiovascular disease, high blood pressure, certain cancers, sleep apnoea, and joint problems.
Healthy weight ranges by height — imperial (US)
| Height | Healthy Weight Range (BMI 18.5–24.9) |
|---|---|
| 5'0" | 97 – 128 lbs |
| 5'2" | 104 – 135 lbs |
| 5'4" | 110 – 144 lbs |
| 5'6" | 118 – 154 lbs |
| 5'8" | 125 – 164 lbs |
| 5'10" | 132 – 174 lbs |
| 6'0" | 140 – 184 lbs |
| 6'2" | 148 – 194 lbs |
Healthy weight ranges by height — metric
| Height | Healthy Weight Range (BMI 18.5–24.9) |
|---|---|
| 1.55 m | 44 – 60 kg |
| 1.60 m | 47 – 64 kg |
| 1.65 m | 50 – 68 kg |
| 1.70 m | 54 – 72 kg |
| 1.75 m | 57 – 76 kg |
| 1.80 m | 60 – 81 kg |
CDC Obesity Classes 1, 2 and 3 — What They Mean
The CDC subdivides obesity into three classes because the health risks and appropriate interventions differ significantly across the range.
Class 1 Obesity — BMI 30 to 34.9
Class 1 is the entry level of obesity classification. At this level, providers typically recommend lifestyle modification (improved diet and increased physical activity), monitoring for related conditions (blood pressure, blood glucose, cholesterol), and discussion with a primary care provider about a structured weight management plan.
Class 2 Obesity — BMI 35 to 39.9
Class 2 carries significantly elevated health risks. At this level, healthcare providers may discuss structured weight loss programs, weight loss medications (where clinically appropriate), and more frequent monitoring of weight-related health conditions.
Class 3 Obesity — BMI 40 and above (Severe Obesity)
Class 3, also called Severe Obesity, carries the highest health risks. At this level, healthcare providers may assess eligibility for bariatric surgery (weight loss surgery), intensive behavioural intervention programmes, and comprehensive management of associated conditions.
Are CDC BMI Categories the Same for Men and Women?
Yes — CDC BMI categories are the same for men and women.
The thresholds of 18.5, 25, and 30 apply to all adults aged 20 and over regardless of sex or race. This is confirmed by official CDC guidance.
However, women naturally carry a higher percentage of body fat than men at the same BMI. Some researchers argue that separate male/female thresholds would be more clinically accurate — but the CDC has not formally adopted different thresholds by sex.
CDC BMI Categories — Are They the Same Regardless of Age?
For adults aged 20 and over — yes, the same categories apply at any age. A BMI of 27 means "overweight" whether you are 25 or 65.
However, some considerations apply. For adults over 65, research suggests slightly higher BMI may be protective, reducing the risk of frailty, falls, and fractures — though the CDC's official categories remain unchanged.
Under 20: The CDC uses a completely different system for people aged 2 to 19 — BMI percentile charts that account for age and sex. The adult BMI categories do not apply to children or teenagers.
CDC BMI and Race — Important Considerations
Research increasingly shows that standard BMI categories may not equally predict health risk across all racial and ethnic groups. People of Asian descent, in particular, tend to have higher health risks at lower BMI values than the standard categories suggest.
The UK's NHS has formally adopted lower BMI thresholds for adults of South Asian, Chinese, Black African, and Caribbean heritage. The CDC has not yet formally adopted ethnicity-adjusted thresholds in the same way — though US clinical guidelines increasingly acknowledge these differences, and individual healthcare providers may apply clinical judgement accordingly.
CDC BMI vs NHS BMI — Key Differences
| CDC (US) | NHS (UK) | |
|---|---|---|
| Healthy weight | 18.5 – 24.9 | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 | 25.0 – 29.9 |
| Obesity | 30.0 and above | 30.0 and above |
| Age cutoff (adults) | 20 years and over | 18 years and over |
| Ethnicity adjustments | Not formally adopted | Formally adopted (NICE) |
| Same for men and women? | Yes | Yes |
The core thresholds are identical — both systems use WHO international standards. The main practical difference is that the NHS has formalised ethnicity-adjusted thresholds, while US clinical practice handles this on a case-by-case basis.
Limitations of CDC BMI Categories
The CDC acknowledges that BMI is a screening tool — not a complete measure of health. Key limitations include:
BMI cannot distinguish muscle from fat
People with a lot of muscle might have a BMI in the overweight range despite very low body fat. This is why athletes and very muscular individuals often have misleadingly high BMI readings.
BMI does not show fat distribution
Visceral fat (stored around the abdominal organs) carries far greater health risks than subcutaneous fat stored elsewhere. Two people with identical BMIs can have very different health risk profiles.
BMI was developed on a limited population
The BMI formula was originally developed in the 19th century using data predominantly from white European men — not a representative sample of the global population it is now applied to.
BMI is a screening tool — not a diagnosis
A healthcare provider can evaluate a person to get a more complete health picture. BMI should always be considered alongside other clinical measures, not in isolation.
What to Do Based on Your CDC BMI Category
Underweight (below 18.5)
Speak to your doctor. Being underweight can indicate nutritional deficiency, underlying health conditions, or other issues that need assessment.
Healthy weight (18.5 – 24.9)
Maintain your weight through a balanced diet and regular physical activity. Focus on overall health habits, not just the number.
Overweight (25 – 29.9)
Lifestyle changes — improved diet and more physical activity — can bring BMI back into the healthy range. Even modest weight loss of 5–10% reduces health risks significantly.
Obesity Class 1, 2, or 3 (30 and above)
Speak to your healthcare provider. They can assess your overall health picture and recommend appropriate support, which may include structured weight management programmes, medication, or surgery depending on your situation.
Calculate Your CDC BMI Category
Instant result in imperial or metric. All CDC BMI categories including obesity classes 1, 2, and 3 — no sign-up required.
Summary — CDC BMI Categories 2026
| BMI | CDC Category | Action |
|---|---|---|
| Below 18.5 | Underweight | Consult healthcare provider |
| 18.5 – 24.9 | ✅ Healthy Weight | Maintain with diet and activity |
| 25.0 – 29.9 | Overweight | Lifestyle changes recommended |
| 30.0 – 34.9 | Obesity Class 1 | Speak to doctor |
| 35.0 – 39.9 | Obesity Class 2 | Medical support recommended |
| 40.0 and above | Obesity Class 3 (Severe) | Specialist assessment available |
- ✅ Same categories for men and women
- ✅ Same categories for all races and ethnicities (official CDC guidance)
- ✅ Applies to adults aged 20 and over
- ✅ Children and teens use separate percentile charts
Frequently Asked Questions
What are the CDC BMI categories for adults?
The CDC uses four main BMI categories for adults aged 20 and over: underweight (below 18.5), healthy weight (18.5 to less than 25), overweight (25 to less than 30), and obesity (30 and above). Obesity is further divided into Class 1 (30–34.9), Class 2 (35–39.9), and Class 3 or severe obesity (40 and above).
Are CDC BMI categories the same for men and women?
Yes. The CDC uses the same BMI categories for all adults aged 20 and over regardless of sex, age, or race. The same thresholds of 18.5, 25, and 30 apply to everyone.
What BMI does the CDC consider healthy?
The CDC defines a healthy BMI as 18.5 to less than 25.0 for adults aged 20 and over. This range is associated with the lowest risk of weight-related chronic diseases.
What is CDC BMI Class 1 obesity?
Class 1 obesity is a BMI of 30 to less than 35. It is the entry level of the obesity classification — associated with increased health risks, and typically managed through lifestyle changes and medical monitoring.
What BMI is considered severely obese by the CDC?
A BMI of 40 or above is classified as Class 3 obesity, also called severe obesity, by the CDC. This category carries the highest health risks and may be assessed for bariatric surgery or intensive weight management programmes.
How does CDC BMI differ from NHS BMI?
The core thresholds are identical — both use the WHO international standards of 18.5, 25, and 30. The main difference is that the UK NHS has formally adopted lower BMI thresholds for certain ethnic groups (South Asian, Chinese, Black African/Caribbean), while the CDC has not yet done so formally.
Does CDC BMI change with age for adults?
No. The standard adult CDC BMI categories apply to all adults aged 20 and over regardless of age. Children and teenagers use a separate percentile-based system.
What is a healthy BMI for a woman according to the CDC?
The CDC uses the same healthy BMI range for women as for men: 18.5 to less than 25. BMI categories do not differ by sex for adults aged 20 and over.
All CDC BMI categories and thresholds are sourced from official Centers for Disease Control and Prevention (CDC) guidance, current as of 2026. This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for personalised health guidance.