⚖️ BMI Calculator
cm
kg
Enter your details and click Calculate
Your BMI score, category, healthy weight range, BMI chart, and personalized insights will appear here.
Calculating your results…
How It Works
How BMI Is Calculated — Formula, Categories & Limitations
BMI is a simple screening tool. Understanding the formula and its limits helps you interpret your number correctly.
The BMI Formula
Metric Formula
BMI = weight (kg) ÷ height² (m²)
Imperial Formula
BMI = (weight lbs × 703) ÷ height² (in²)
BMI Prime = BMI ÷ 25 (1.0 = top of healthy range)
Ponderal Index = weight (kg) ÷ height³ (m³)
Worked Example: 70 kg, 170 cm tall
1
Convert height: 170 cm = 1.70 m
2
Square height: 1.70 × 1.70 = 2.89 m²
3
Divide weight: 70 ÷ 2.89 = 24.2
✓ BMI = 24.2 — Healthy weight range · BMI Prime = 0.97
BMI Categories (WHO Standard)
| Category | BMI Range |
|---|---|
| Underweight | Below 18.5 |
| Healthy weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II | 35.0 – 39.9 |
| Obese Class III | 40.0 and above |
Why BMI Has Limits
- Muscle vs fat: Athletes can have high BMI with low body fat
- Age: Older adults may have normal BMI but high body fat due to muscle loss
- Ethnicity: Asian populations face higher health risks at lower BMI values
- Sex: Women carry ~10% more body fat than men at the same BMI
- Fat distribution: BMI cannot detect visceral (abdominal) fat
Quick Reference
Healthy Weight Range by Height (kg and lbs)
These weights correspond to a BMI of 18.5–24.9, the standard healthy range for adults. Find your height, or use the calculator above for your exact BMI.
| Height | Feet & inches | Healthy weight (kg) | Healthy weight (lbs) |
|---|---|---|---|
| 150 cm | 4′ 11″ | 42–56 kg | 92–124 lbs |
| 155 cm | 5′ 1″ | 44–60 kg | 98–132 lbs |
| 160 cm | 5′ 3″ | 47–64 kg | 104–141 lbs |
| 165 cm | 5′ 5″ | 50–68 kg | 111–149 lbs |
| 170 cm | 5′ 7″ | 53–72 kg | 118–159 lbs |
| 175 cm | 5′ 9″ | 57–76 kg | 125–168 lbs |
| 180 cm | 5′ 11″ | 60–81 kg | 132–178 lbs |
| 185 cm | 6′ 1″ | 63–85 kg | 140–188 lbs |
| 190 cm | 6′ 3″ | 67–90 kg | 147–198 lbs |
| 195 cm | 6′ 5″ | 70–95 kg | 155–209 lbs |
For adults aged 20 and over. For adults of Asian descent, health risk starts to rise from about BMI 23, so the upper end of a healthy range is lower (BMI 22.9).
Reference Guide
Healthy BMI Range by Age — Adults
WHO and CDC use 18.5–24.9 for all adults. Some research suggests that in older adults a slightly higher BMI is linked to lower risk of frailty and fracture. That is not an official range, so treat the notes below as context, not a target.
| Age Group | Standard BMI Range | Notes |
|---|---|---|
| 18–24 | 18.5 – 24.9 | Standard WHO range applies |
| 25–34 | 18.5 – 24.9 | Standard range; monitor waist circumference |
| 35–44 | 18.5 – 24.9 | Standard range; metabolic risk rises toward 25+ |
| 45–54 | 18.5 – 24.9 | Waist circumference becomes an important co-indicator |
| 55–64 | 18.5 – 24.9 | Standard range; some research suggests little added risk up to about BMI 27 at this age. Discuss with your doctor |
| 65+ | 18.5 – 24.9 | Standard range; some studies link a BMI of about 22–27 with lower risk of frailty and fracture, and below 22 with higher risk. Discuss with your doctor |
Source: WHO and CDC adult BMI categories. The age-related notes summarise published research and are not WHO or CDC ranges. Last updated October 2026.
Healthy BMI by Ethnicity
Different ethnic groups carry health risk at different BMI thresholds. Our calculator applies these automatically when you select your ethnicity.
| Ethnicity | Overweight threshold | Obese threshold | WHO recommendation |
|---|---|---|---|
| General / White / Black / Hispanic | BMI 25.0 | BMI 30.0 | Standard cutoffs |
| East & South-East Asian | BMI 23.0 | BMI 27.5 | WHO 2004 public-health action points |
| South Asian (Indian subcontinent) | BMI 23.0 | BMI 27.5 | WHO 2004 public-health action points |
FAQ
BMI Calculator — Frequently Asked Questions
Answers to the most common questions about BMI, healthy weight ranges, and how to interpret your result.
Enter your height and weight in the calculator above (kg and cm, or lbs and feet/inches) and click Calculate. BMI is your weight in kilograms divided by your height in metres squared. For example, 70 kg at 170 cm gives 70 ÷ 1.70² = 24.2.
A healthy BMI for adults is between 18.5 and 24.9. For adults of Asian or South Asian descent, health risk starts to rise from about BMI 23, so this calculator uses 23 as the overweight point when you select those groups.
BMI = weight (kg) ÷ height² (m²). In imperial units: BMI = (weight in lbs × 703) ÷ height² (inches).
The healthy BMI range is 18.5–24.9 for all adults regardless of sex. However, women typically have more body fat than men at the same BMI, so BMI should be read alongside waist circumference and other health markers.
WHO and CDC use the same 18.5–24.9 range for all adults. Some research suggests that in older adults a BMI of roughly 22–27 is linked to lower risk of frailty and fracture, and that a BMI below 22 is linked to higher risk. This is not an official range, so talk to your doctor about what is right for you.
Yes. For most adults, a BMI of 25.0 is the start of the overweight category under WHO and CDC guidelines. For adults of Asian or South Asian descent, this calculator uses 23.0 as the overweight point.
A BMI of 30 or above is classified as obese (Class I: 30–34.9, Class II: 35–39.9, Class III: 40+). For Asian populations the public-health action point for obesity is 27.5.
BMI Prime is your BMI divided by 25 (the top of the standard healthy range). A value of 1.0 means you are exactly at the top of the healthy range. Above 1.0 is overweight or obese; 0.74–1.0 is healthy; below 0.74 is underweight.
The Ponderal Index (PI) = weight (kg) ÷ height³ (m³). It uses height cubed instead of squared, so it changes less with height than BMI does. BMI remains the standard screening measure, and the Ponderal Index is shown here for reference.
Yes. Athletes with high muscle mass may have a BMI in the overweight range without excess body fat. Someone with a normal BMI can also have high body fat if they have low muscle mass. BMI is a screening tool, not a diagnosis.
A 2004 WHO expert consultation identified BMI 23 and 27.5 as public-health action points for Asian populations, because health risk rises at lower BMI than in other groups. National guidelines differ (for example, China uses 24 and 28), so ask your doctor which cut-offs apply to you.
For ages 2–19, BMI is compared with other children of the same age and sex and given as a percentile (CDC growth charts): below the 5th percentile is underweight, 5th to below 85th is healthy weight, 85th to below 95th is overweight, and 95th or above is obese. This calculator shows the BMI value only. Use the CDC BMI-for-age calculator or ask a doctor for the percentile.