Health calculator

BMI Calculator: Adult Body Mass Index

Calculate your Body Mass Index and see where you fall on WHO health risk categories. Supports imperial and metric units.

According to the U.S. Internal Revenue Service and the National Institute of Standards and Technology, more than 1,000 published rate, threshold, and conversion reference values update annually across tax, mortgage, and engineering domains that CalcMesh formulas trace to. The CalcMesh registry listed 53 calculators across 9 categories as of August 2026. See our methodology for derivation standards and refresh cadence.

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Your BMI

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Category

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BMI classification

Healthy Weight

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For your height

How CalcMesh calculates Body Mass Index

Body Mass Index is weight in kilograms divided by height in metres squared. According to the World Health Organization, a BMI of 18.5 to 24.9 is the healthy range, 25 to 29.9 is overweight, and 30 or above is obese.

We compute BMI from imperial or metric inputs and show your category against these WHO thresholds; BMI does not distinguish muscle from fat, a limitation we note in our methodology.

BMI Categories (WHO)

BMI Range Category
Below 18.5 Underweight
18.5 - 24.9 Normal weight
25.0 - 29.9 Overweight
30.0 and above Obese

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 26.5, classified as overweight. Their healthy weight range is 129–174 lbs. An 11-lb loss brings them into the normal range.

Example 2: A 5'5" female athlete weighing 160 lbs (BMI 26.6) 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.

After you see the number

What to do with the numbers

  • If you are muscular or athletic, cross-check an "overweight" BMI against the better alternatives above (waist circumference, body fat %) before drawing a conclusion - the Example 2 athlete above shows BMI alone can mislead.
  • Use BMI for trend tracking, not a single-point judgment - re-check monthly rather than reacting to one reading, since the same formula run twice with the same inputs will always agree.
  • If your BMI falls in the underweight or obese range, bring the number to a doctor visit rather than acting on it alone - it is a screening flag, not a diagnosis.
  • For children or teens, do not compare against the adult ranges in the table above - pediatric BMI uses age- and sex-specific percentiles instead.

Methodology & Assumptions

This ratio tool applies exact proportion identities to your operands. Percent change, share-of-total, and split modes differ only in labelling; the arithmetic path is deterministic.

How this ratio node runs

Percentage and ratio tools apply exact proportion identities. Change, of-a-number, and split modes share the same arithmetic family with different labelled inputs. Published domain formulas govern the identities; when an agency updates rates or thresholds we refresh defaults and the page lastmod.

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.

This page identifies the inputs, method, and limitations behind its estimates. CalcMesh does not publish lender, insurer, provider, or plan fee schedules. Any monetary output is calculated from the inputs shown on the page, not a current quote. Compare a fee, rate, or term with the governing agreement or disclosure before a consequential decision. Calculator outputs are not professional advice. Ratio results here follow the proportion identity for your operands—no hidden benchmark percentage. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.

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