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US CDC 2026 Standards100% FreePrivacy Protected
Free BMI Calculator
Calculate your Body Mass Index instantly using CDC guidelines. Get your healthy weight range, personalized health tips, and evidence-based recommendations — no sign-up required. All calculations run privately in your browser.
✓ Content reviewed against CDC 2026 guidelinesLast updated: May 2026
Why Trust This Calculator
Accurate, private, and built on established medical guidelines.
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CDC-Aligned Standards
BMI categories follow US CDC 2026 adult guidelines — the same classification system used by healthcare providers nationwide.
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100% Private & Local
All calculations run in your browser. No data is ever sent to our servers. No account required. Your measurements stay on your device.
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Medically Reviewed
Health information is researched against peer-reviewed literature and official CDC, WHO, and NIH guidelines.
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Transparent Limitations
We clearly explain what BMI can and cannot tell you. No oversimplified claims — just honest, evidence-based information.
How to Use This Calculator
Six simple steps — from measurement to meaningful results.
Step 1
Choose Units
Select Imperial (ft, in, lbs) or Metric (cm, kg). Switch anytime — results update automatically in both systems.
Step 2
Measure Accurately
Measure height without shoes against a wall. Weigh yourself in the morning, before eating, wearing light clothing for best accuracy.
Step 3
Enter Numbers
Type your height and weight into the input fields. Results appear instantly as you type — no submit button needed.
Step 4
Read Your Results
See your BMI number, weight category with color coding, healthy weight range for your height, and personalized health tips.
Step 5
Save & Track
Save calculations to browser history to track changes over time. Up to 10 records stored locally on your device — never on our servers.
Step 6
Consult a Professional
BMI is a screening tool — not a diagnosis. Discuss your results with a healthcare provider for a comprehensive health assessment.
BMI Categories & Health Risks
Understanding each CDC weight classification and its associated health implications.
Underweight
BMI below 18.5
May indicate malnutrition, eating disorders, or underlying medical conditions. Associated with weakened immune function, bone density loss, and hormonal disruption. Unintentional weight loss warrants medical evaluation.
Healthy Weight
BMI 18.5 – 24.9
Associated with the lowest overall health risk for most adults. Maintain with a balanced diet rich in vegetables and whole grains, 150+ minutes of weekly exercise, adequate sleep, and regular health screenings.
Overweight
BMI 25.0 – 29.9
Modestly elevated risk for type 2 diabetes, hypertension, and cardiovascular disease. Even a 5–10% reduction in body weight can measurably improve blood pressure, cholesterol, and blood sugar levels.
Obese Class I
BMI 30.0 – 34.9
7–10× higher risk of type 2 diabetes compared to healthy weight. ~40% prevalence of sleep apnea at this BMI level. Medical consultation and structured weight management are recommended.
Obese Class II
BMI 35.0 – 39.9
Substantially elevated risk for all major chronic diseases. Over 50% of people at this BMI have undiagnosed sleep apnea. Bariatric surgery and GLP-1 medications may be medically appropriate — discuss with your doctor.
Obese Class III
BMI 40.0 and above
Severe obesity with significantly elevated mortality risk. Comprehensive multidisciplinary care is essential — including medical, nutritional, behavioral, and potentially surgical interventions. Seek professional support.
Important: BMI is a screening tool, not a diagnostic test. It does not distinguish muscle from fat, account for body composition, or measure fat distribution. Two people with the same BMI can have very different health profiles. Waist circumference, body fat percentage, blood work, and family history provide a more complete picture. Always discuss your BMI result with a qualified healthcare provider.
Obesity Statistics at a Glance
The numbers behind why BMI matters — sourced from major public health authorities.
42.4%
US Adult Obesity Rate
CDC National Health and Nutrition Examination Survey 2017–2020. Up from 30.5% in 1999–2000.
73.6%
Overweight or Obese
Combined overweight (BMI ≥25) and obesity (BMI ≥30) prevalence among US adults aged 20 and older.
2.5 Billion
Overweight Adults Worldwide
WHO 2024 global estimate. Over 890 million adults are living with obesity (BMI ≥30) globally.
5–10%
Weight Loss = Real Health Gains
Even modest weight loss significantly improves blood pressure, LDL cholesterol, triglycerides, and fasting glucose.
Sources: CDC NCHS Data Brief (2023), WHO Global Health Observatory (2024), NIH National Heart, Lung, and Blood Institute
Related Health Articles
Evidence-based guides covering weight management, special populations, health risks, and BMI science.
According to the US CDC, a healthy BMI for adults is between 18.5 and 24.9. Below 18.5 is underweight, 25.0–29.9 is overweight, and 30.0 or above is obese. Always consult a doctor for a comprehensive assessment.
The BMI formula and CDC categories are identical for adult men and women. However, at the same BMI value, women typically have more body fat than men, which is why doctors may also measure waist circumference and body composition.
BMI is a useful population-level screening tool but has limitations. It doesn't distinguish muscle from fat, and athletes with high muscle mass may have a high BMI without excess body fat. Healthcare providers combine BMI with other measures for a full picture.
No — this is one of BMI's biggest limitations. Muscle weighs more than fat by volume, so very muscular individuals often have an elevated BMI despite having low body fat. Bodybuilders, athletes, and people who do heavy strength training may be classified as "overweight" or even "obese" when they are actually very lean. For these individuals, body fat percentage or waist circumference are more meaningful metrics.
No — this calculator is for adults aged 20 and older. For children and teens (ages 2–19), use the CDC's BMI-for-age percentile system or consult a pediatrician.
Yes — research shows that people of South Asian, East Asian, and Southeast Asian descent tend to have higher body fat percentages at the same BMI compared to people of European descent. The WHO recommends lower BMI thresholds for Asian populations: overweight at 23.0 (instead of 25.0) and obese at 27.5 (instead of 30.0). If you are of Asian descent, discuss appropriate thresholds with your doctor.
Sustainable weight loss involves a modest calorie reduction, regular physical activity combining cardio and strength training, adequate sleep, stress management, and limiting ultra-processed foods. Always consult a healthcare provider before starting any weight loss program.
For adults aged 20–65, the standard CDC healthy range of 18.5–24.9 applies. However, for adults over 65, some research suggests a slightly higher BMI (23–27) may be protective — a phenomenon called the "obesity paradox." Older adults with modestly higher BMI sometimes have better outcomes when facing illness. Discuss your target range with your geriatrician or primary care doctor.
For most adults, checking BMI every 3–6 months provides a useful trend without causing unnecessary fixation. Weight naturally fluctuates daily by 1–3 kg (2–6 lbs), so avoid checking too frequently. More important than any single BMI reading is the direction of change over time. If your BMI is trending steadily upward or downward, discuss it with your healthcare provider.
Yes — the BMI formula is a straightforward mathematical calculation: weight ÷ height². As long as you input accurate measurements, any BMI calculator using the standard formula will produce the same result. The formula itself is standardized globally. What varies is the interpretation: different organizations may use slightly different category labels, and not all calculators provide the context and limitations that this one does. If a calculator asks for payment, personal information, or tries to sell you supplements based on your result, avoid it.