BMI Calculator
※ BMI is a general reference. Individual results may vary based on body fat percentage or muscle mass.
BMI Basis and Interpretation Limits
Reference date and last reviewed: July 10, 2026
Calculation Basis
Calculates BMI as weight in kilograms divided by height in meters squared, then displays the range under the selected Asian adult or WHO international adult standard.
Reference Limits
BMI is a screening measure, not a direct measurement of body fat. It cannot distinguish muscle from fat distribution, and general adult ranges may not apply to pregnancy, growing children and adolescents, or highly trained athletes.
When to Confirm Officially
If your weight changes unexpectedly or you are being treated for a weight-related condition, do not interpret one BMI value alone. Review it with body composition, waist measurement, test results, and a health professional.
Usage Tips
Check BMI trends together with changes in height and weight
BMI is a quick reference for checking weight status from height and weight, but it does not fully reflect muscle mass, body fat percentage, or body shape differences. Use the result as a health management guide together with weight trends and lifestyle habits instead of judging by the number alone.
What is BMI Calculator?
The BMI Calculator divides weight by height squared and classifies the result with either the Asia-Pacific or WHO adult cutoffs. BMI is a screening measure rather than a direct body-fat measurement, diagnosis, or personalized treatment target.
How to Use
- 1Enter height in centimeters. The calculator converts it to meters before squaring it.
- 2Enter current weight in kilograms.
- 3Choose the Asia-Pacific or WHO adult classification.
- 4Review the BMI number and the category produced by the selected cutoffs.
- 5Do not use the category alone to judge health; consider waist measurement, body composition, clinical values, and individual context.
BMI formula and adult cutoffs
Last reviewed: July 10, 2026What this calculator computes
BMI = weight (kg) ÷ [height (m)]²
The BMI number stays the same when you switch standards; only the category cutoffs change. The Asia-Pacific option marks 23 as overweight and 25 as obesity, while the WHO option uses 25 and 30.
Example: 170 cm and 70 kg
- • Height: 170 cm = 1.70 m
- • Weight: 70 kg
- • Asia-Pacific standard selected
- 1. 1.70 × 1.70 = 2.89
- 2. 70 ÷ 2.89 = 24.22
BMI is 24.22. This tool labels it overweight under the Asia-Pacific option and normal under the WHO option.
How to read the result
- BMI is a quick weight-status screening measure, not a direct measurement of body fat.
- People with the same BMI can have different waist measurements, muscle mass, blood pressure, glucose, and lipid risk.
- Near a cutoff, consider the unrounded value and the measurement trend instead of relying on the displayed category alone.
Conditions that change the result
- These categories are for adults. Children and teenagers require age- and sex-specific BMI percentiles.
- Pregnancy, high muscularity, edema, and age-related muscle loss can make BMI less representative of body composition.
- Switching between Asia-Pacific and WHO changes the category but never changes the calculated BMI.
Common input mistakes
- A common manual error is squaring 170 instead of converting 170 cm to 1.70 m first.
- Do not enter pounds or feet and inches directly into fields labeled kilograms and centimeters.
- Using height and weight measured under very different conditions can make trend comparisons misleading.
Reference Knowledge
- ●Mathematical Formula: BMI = Weight (kg) / [Height (m) × Height (m)]. Height in centimeters must be converted to meters and squared for the calculation.
- ●WHO International Criteria: BMI < 18.5 is Underweight, 18.5 to 24.9 is Normal Range, 25.0 to 29.9 is Overweight, and 30.0 or higher is classified as Obesity.
- ●Asia-Pacific Regional Criteria: BMI < 18.5 is Underweight, 18.5 to 22.9 is Normal Range, 23.0 to 24.9 is Pre-obese (Overweight), 25.0 to 29.9 is Class I Obesity, 30.0 to 34.9 is Class II Obesity, and 35.0+ is Class III (Severe) Obesity.
- ●Clinical Limits of BMI: Because BMI relies solely on total weight, it does not distinguish between muscle tissue, bone density, body water, and fat mass. Muscular individuals or athletes may be misclassified as overweight, while sedentary older adults with sarcopenia may display a 'normal' BMI despite having high visceral fat levels.
FAQ
Q.Can two people with the same BMI have different body-fat percentages?
Yes. BMI uses only height and weight, so it cannot tell whether weight comes from muscle, fat, or fluid. Two people with the same BMI can have different body-fat percentages and waist measurements; use other measurements when that distinction matters.
Q.Why does the category change between the Asia-Pacific and WHO options?
Both options use the same BMI formula but apply different adult cutoffs. For example, a BMI of 24.22 is overweight under this tool’s Asia-Pacific option and within the normal range under the WHO option. Switching standards never changes the BMI number itself.
Q.Should children and teenagers use the adult BMI cutoffs?
No. Body composition changes with age and sex during growth, so fixed adult cutoffs are not appropriate. Pediatric interpretation uses age- and sex-specific growth charts and BMI percentiles or other locally recommended growth standards.
Q.Does a high BMI mean that I have a disease?
BMI alone cannot diagnose disease. At a population level, higher BMI ranges are associated with greater risk of conditions such as type 2 diabetes, hypertension, and cardiovascular disease. Individual assessment also considers waist measurement, blood pressure, laboratory results, history, and lifestyle.
