By · Reviewed against primary-source formulas

BMI Calculator

Calculate your Body Mass Index to see where you fall on the BMI scale.

lbs
ft
in

Your BMI

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Category

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BMI classification

Healthy Weight

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For your height

BMI Categories (WHO)

BMI RangeCategory
Below 18.5Underweight
18.5 - 24.9Normal weight
25.0 - 29.9Overweight
30.0 and aboveObese

Limitations of BMI

  • Muscle vs. fat: BMI cannot distinguish between muscle mass and body fat. Muscular individuals may have a high BMI while being perfectly healthy.
  • Age and sex: Women naturally carry more body fat than men, and body composition changes with age. BMI does not account for these differences.
  • Ethnicity: Health risks at specific BMI values vary by ethnic background. Some populations face elevated risks at lower BMI levels.
  • Children: BMI is interpreted differently for children and teens, using age- and sex-specific percentiles rather than fixed ranges.

Better Alternatives

  • Waist circumference: A waist measurement above 40 inches (men) or 35 inches (women) suggests increased health risk.
  • Body fat percentage: Measured via calipers, DEXA scans, or bioelectrical impedance, this provides a more accurate picture of body composition.
  • Waist-to-hip ratio: This metric correlates well with cardiovascular disease risk.

When to Use This Calculator

  • General screening: Quick initial check before a doctor visit or when starting a new fitness program.
  • Tracking progress: Monitor BMI changes over months to gauge the direction of weight management efforts.
  • Insurance or health assessments: Many workplace wellness programs use BMI as a baseline metric.

Real-World Examples

Example 1: A 5'10" person weighing 185 lbs has a BMI of 26.6 — classified as overweight. Their healthy weight range is 129–174 lbs. Even a 12-lb loss brings them into the normal range.

Example 2: A 5'5" female athlete weighing 160 lbs (BMI 26.7) with 18% body fat is classified as overweight by BMI but is within fitness-level body fat ranges — a case where body fat % is more informative.

Data Sources

BMI formula: weight(kg) / height(m)². Categories per WHO Global Database on Body Mass Index. Healthy weight range derived from BMI 18.5–24.9 bounds. Imperial formula: (weight(lbs) / height(in)²) × 703.

Disclaimer: This calculator provides estimates for informational purposes only. Consult your healthcare provider for medical advice.

BMI in Public-Health Context

CDC's NHANES 2017-2020 prevalence data reports 41.9% of U.S. adults have obesity (BMI ≥ 30), up from 30.5% in 1999-2000. Severe obesity (BMI ≥ 40) affects 9.2% of adults — triple the 3.1% rate in 1999. Overweight (BMI 25-29.9) adds another 31.1%, meaning 73% of U.S. adults are above the 'normal weight' range.

BMI is a screening tool, not a diagnosis. The NIH explicitly notes that BMI can misclassify muscular individuals as overweight and overlook visceral adiposity in thinner frames. Newer metrics like waist-to-height ratio (threshold 0.5) and Relative Fat Mass have better specificity in research — a 2023 PLOS One study of 4,000 adults found waist-to-height predicted cardiometabolic risk 15% more accurately than BMI alone.

Economic burden: the CDC estimates obesity-related medical spending reached $173 billion/year in 2019 dollars, with obese adults averaging $1,861 more in annual medical costs than normal-weight peers. Weight distribution varies by state — Mississippi (40.8%), West Virginia (40.6%), and Louisiana (40.1%) led adult-obesity prevalence in 2023, while Colorado (24.9%) and Hawaii (26.4%) were lowest, per the CDC BRFSS.

Sources: CDC NHANES 2017-2020, NIH BMI guidelines, CDC BRFSS state data

Methodology & Assumptions

This calculator implements standard formulas drawn from primary-source authorities. Values are point-in-time estimates; consult a licensed professional for high-stakes decisions. See the per-input definitions and source citations below.

How this works

Computations are deterministic and run client-side — no inputs leave your browser. Formulas are derived from standard published formulas for the calculator's domain (mortgage, taxes, energy, conversions, etc.). When the underlying agency publishes updated rates or thresholds we refresh defaults and update the page's lastmod timestamp.

Frequently Asked Questions

Is BMI accurate?
BMI is a useful screening tool for the general population, but it has significant limitations. It does not distinguish between muscle and fat mass, so athletes or people with high muscle mass may be classified as overweight despite being healthy. It also does not account for bone density, age, sex, or ethnicity, all of which affect what constitutes a healthy weight.
What's a healthy BMI?
A BMI between 18.5 and 24.9 is generally considered normal weight for adults. However, a healthy BMI can vary by individual. Some people with a BMI slightly outside this range are perfectly healthy, while others within the range may have metabolic issues. BMI should be considered alongside other health indicators.
Is BMI different for athletes?
Yes. Athletes and bodybuilders often have a high BMI due to increased muscle mass rather than excess body fat. Muscle weighs more than fat by volume, so someone who is muscular may appear overweight or obese by BMI standards while having a low body fat percentage. For athletes, body fat percentage is a more meaningful measurement.
Should I worry about my BMI?
BMI is one data point among many. If your BMI falls outside the normal range, it is worth discussing with your healthcare provider, but it does not automatically mean you are unhealthy. Factors like waist circumference, blood pressure, cholesterol, blood sugar, physical activity level, and family history paint a more complete picture of your health.

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Inputs, defaults, and authoritative sources
Input Default Source / authority
All inputs Domain-typical defaults Editorial methodology, CalcMesh 2026