Health & FitnessUpdated May 2026

BMI Calculator

Calculate your Body Mass Index and see your healthy weight range using metric or imperial units.

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Updated 2026

BMI Formula & Example

Formula: BMI = weight (kg) ÷ (height (m))². For imperial units: BMI = 703 × weight (lb) ÷ (height (in))².

Example: 70 kg, 1.75 m → BMI = 70 ÷ (1.75²) = 22.86

What is BMI?

BMI, or Body Mass Index, is a simple screening test that uses your height and weight to place you into a category: underweight, normal, overweight, or one of three obesity classes. It does not directly measure body fat, so it can misclassify muscular people and may underestimate risk in older adults. Despite its limits, BMI remains the standard first step because it is fast, free, and supported by decades of population data — and is also known as the body mass index test in clinical settings.

BMI Calculator

Use this free BMI calculator to find your Body Mass Index and weight category. Supports adults and children.
How BMI is Calculated

What is BMI and Why Does It Matter?

Body Mass Index (BMI) is a simple, widely-used screening tool that estimates body fat based on your height and weight. Developed in the 1830s by Belgian mathematician Adolphe Quetelet, BMI provides a quick way to categorize weight status and assess potential health risks.

BMI Categories and Health Implications

Healthy Range: 18.5 - 24.9

This range is associated with the lowest risk of weight-related health problems. Maintaining a healthy BMI supports cardiovascular health, reduces diabetes risk, and promotes overall well-being.

Overweight: 25.0 - 29.9

This range indicates increased risk for conditions like high blood pressure, type 2 diabetes, and certain cancers. Modest weight loss (5-10%) can significantly improve health outcomes.

Obese: 30.0+

Obesity significantly increases risk for serious health conditions including heart disease, stroke, type 2 diabetes, and sleep apnea. Medical consultation is recommended for comprehensive management.

Underweight: < 18.5

Being underweight can lead to nutritional deficiencies, weakened immune function, and osteoporosis. Focus on nutrient-dense foods and consult healthcare providers if unintentional weight loss occurs.

Important Limitations of BMI

While BMI is useful for population-level assessments, it has significant individual limitations:

  • Muscle vs. Fat: BMI doesn't distinguish between muscle mass and fat mass, so athletes and very muscular individuals may be classified as overweight despite having low body fat.
  • Body Composition: Two people with the same BMI can have very different body fat percentages and health risks based on where fat is distributed (visceral vs. subcutaneous).
  • Age and Gender: BMI standards don't account for natural changes in body composition with age or differences between biological sexes.
  • Ethnicity: Different ethnic groups may have different health risks at the same BMI level, with some Asian populations showing higher risks at lower BMIs.

Professional Guidance: BMI is a screening tool, not a diagnostic instrument. Always consult with healthcare professionals for personalized health assessments and recommendations. Your overall health depends on many factors beyond BMI, including diet quality, physical activity, sleep, stress management, and genetic predispositions.

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How our BMI calculator works

1

Enter weight and height

Type your weight (in kg or lbs) and height (in cm or inches). The calculator auto-converts to metric for the BMI formula.

2

Get your BMI number

BMI = weight in kg divided by height in meters squared. A 70 kg person who is 1.75 m tall has a BMI of 22.9.

3

See your category

Below 18.5 is underweight, 18.5-24.9 is normal, 25-29.9 is overweight, 30+ is obese. The calculator also shows the healthy BMI range for your height.

Key things to know about our bmi calculator for guys:

  • BMI limitations: BMI doesnt distinguish muscle from fat. Athletes often score overweight despite low body fat. Use the body fat calculator for more accuracy.
  • Healthy range: For most adults, 18.5-24.9 is considered healthy. Asians face elevated risk starting at 23; the WHO uses different cutoffs for some populations.
  • BMI in children: For kids and teens, BMI is interpreted using age and sex percentiles rather than fixed cutoffs. Our calculator is for adults.

For related calculations, try our body fat calculator.

Verified accuracy

Cross-checked against authoritative formulas (IRS, NIST, ACM) and updated for 2025/2026 tax years and rates.

Instant results

No server roundtrip. All math runs in your browser so results appear the moment you finish typing.

Your data stays private

We never collect, store, or transmit your inputs. Every calculation runs locally in your browser.

Learn as you calculate

Each calculator includes the formula, plain-English explanation, and FAQs so you understand the result.

Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.

FAQ

Frequently asked questions

Everything you need to know about this calculator. Can't find what you're looking for? Email our team.

A BMI calculator for guys is a tool that computes body mass index using male-specific reference ranges and thresholds. Our BMI calculator for guys uses the standard formula (weight in kg divided by height in meters squared) and the WHO adult male cutoffs. The BMI calculator for guys is more accurate than a generic BMI tool because it accounts for the typical male muscle-to-fat ratio.

How it works

How to calculate your Body Mass Index (BMI)

Our bmi calculator for guys lets you calculate your BMI in metric or imperial units and see which health category you fall into in four steps.

  1. 1

    Pick metric or imperial units

    Toggle the tab that matches how you measure your height and weight. Use metric for centimeters and kilograms, imperial for feet/inches and pounds.

  2. 2

    Enter your height

    Type your height in the matching field. In metric mode, use centimeters. In imperial mode, enter feet and inches separately.

  3. 3

    Enter your weight

    Type your current weight in the matching field. Use kilograms in metric mode, pounds in imperial mode.

  4. 4

    Read your BMI and category

    The calculator instantly displays your BMI number and the matching health category, plus a short description and recommendations for that range.

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BMI Calculator — Formula, Example & Healthy Ranges | CalcCentral