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BMI Calculator

Calculate your Body Mass Index (BMI) using metric (kg/cm) or imperial (lb/in) units. BMI categories: Underweight < 18.5, Normal 18.5–24.9, Overweight 25–29.9, Obese ≥ 30.

Written by CalcVault Editorial Team
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cm
lb
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Fill in the fields above and click Calculate to see your results.

How to use

The BMI (Body Mass Index) Calculator helps assess if you have a healthy body weight for your height. First, select your preferred measurement system (Metric for kg/cm or Imperial for lbs/inches). Enter your weight and height accurately in the provided fields. The calculator instantly processes these figures using the standard BMI formula (weight divided by height squared) to produce your BMI score. It also categorizes your result (e.g., Underweight, Normal weight, Overweight, or Obese) according to World Health Organization (WHO) guidelines, giving you a quick snapshot of your general health status.

How it's calculated

BMI (Metric)

weight_kg / pow(height_cm / 100, 2)

BMI calculated from kg and cm

BMI (Imperial)

703 * weight_lb / pow(height_in, 2)

BMI calculated from lb and inches

Your BMI

(unit_system == 1) * bmi_metric + (unit_system == 2) * bmi_imperial

BMI < 18.5: Underweight | 18.5–24.9: Normal | 25–29.9: Overweight | ≥ 30: Obese

Examples

Average adult: 70 kg, 170 cm

  • Height (cm):170
  • Height (inches):67
  • Weight (kg):70
  • Weight (lb):154
  • Unit System:1

Result

  • Your BMI:22.5
  • category:Normal weight

For a person weighing 65kg with a height of 170cm, the BMI is 22.5. This falls into the 'Normal weight' category, which indicates a healthy balance between height and weight according to WHO guidelines.

Slightly overweight: 80 kg, 175 cm

  • Height (cm):175
  • Height (inches):69
  • Weight (kg):80
  • Weight (lb):176
  • Unit System:1

Result

  • Your BMI:26.1

A 175 cm person weighing 80 kg has a BMI of 26.1 — classified as 'overweight' by WHO (BMI 25–29.9). For an Asian adult, where health risks often appear at lower BMI thresholds, a target of 23 or below is recommended by many Asian health guidelines.

Industry Benchmarks

Metric Typical Range
A healthy BMI is typically between 18.5 and 24.9. 22.5

Data source: WHO Standard

Frequently Asked Questions

What is BMI and what do the numbers mean?

BMI (Body Mass Index) is a number calculated from your weight and height. Categories: Underweight (< 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), Obese (≥ 30). It is a screening tool, not a diagnostic measure.

Is BMI accurate for everyone?

BMI has limitations. It does not account for muscle mass, bone density, age, or fat distribution. Athletes may have a high BMI due to muscle, while older adults may have a normal BMI but excess body fat. Always consult a healthcare professional for a full assessment.

What is a healthy BMI for Vietnamese adults?

The World Health Organization uses 18.5–24.9 as the normal range globally. However, some Asian health guidelines suggest a lower overweight threshold of 23.0 due to differences in body composition. Consult your doctor for personalised advice.

Is BMI accurate for athletes or bodybuilders?

No, BMI can be misleading for athletes or individuals with high muscle mass. Because muscle is denser than fat, a bodybuilder might have a high BMI indicating obesity, despite having a very low body fat percentage.

Are the BMI categories the same for men and women?

Yes, the standard BMI categories defined by the WHO apply equally to both adult men and women over the age of 20.
CalcVault Editorial Team

CalcVault Editorial Team

Verified Content Team

The CalcVault Editorial Team is a group of finance, health, and mathematics specialists dedicated to producing accurate, bilingual calculator content for Vietnamese and global small business owners. Every formula on CalcVault undergoes rigorous source verification against authoritative bodies including the IRS, CFPB, CDC, WHO, and NIST before publication. Our process includes independent peer review, structured fact-checking, and scheduled content audits to ensure every calculator remains up-to-date with the latest regulatory and scientific standards. We are committed to editorial independence from our advertising partners.

Areas of Expertise

Personal FinanceVietnam Tax & PayrollHealth Metrics & BMIApplied MathematicsBusiness LendingSMB Financial Planning
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