BMI Calculator (Adults: Men & Women)
Enter your height and weight to get your BMI in seconds. Works in kg/cm or lbs/ft; the same categories apply to men and women aged 20+.
How to calculate BMI (the BMI formula)
BMI = weight (kg) ÷ height (m)². In US units: BMI = 703 × weight (lb) ÷ height (in)². Example: 70 kg and 1.75 m → 70 ÷ 3.06 = 22.9. The calculator above does the conversion for you; if you do it by hand, square the height first, then divide.
BMI chart for adults: men and women
| BMI | Category (WHO / CDC) |
|---|---|
| below 18.5 | underweight |
| 18.5 – 24.9 | healthy weight |
| 25.0 – 29.9 | overweight |
| 30.0 – 34.9 | obesity class 1 |
| 35.0 – 39.9 | obesity class 2 |
| 40.0 and above | obesity class 3 |
The same cut-offs are used for adult men and women. For children and teens BMI is read against age-and-sex percentiles instead, so this calculator is for adults only.
What is a normal BMI range?
For adults, 18.5–24.9 is the range linked with the lowest risk of weight-related disease in large population studies. Being slightly above it does not mean you are unhealthy: waist size, blood pressure, blood lipids, fitness and family history matter at least as much. If your BMI is 25 or higher, the waist-to-hip ratio calculator adds the second piece of the picture — where the weight sits.
BMI vs ideal body weight
BMI gives a range; “ideal weight” formulas give a single number from height alone. Neither knows how much of your weight is muscle. Use BMI to see whether you are inside the healthy band, and the ideal weight calculator only as a rough reference point, not a target.
What BMI does not measure
BMI cannot tell fat from muscle. A muscular person can score “overweight” with low body fat, and an older adult can score “healthy” while carrying too little muscle. Pregnancy, very short or very tall stature, and some ethnic backgrounds also shift the risk at a given BMI. When BMI and your mirror disagree, measure body fat or waist instead.
Sources
- WHO, Obesity and overweight fact sheet (2025) — https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight
- CDC, Adult BMI Calculator — https://www.cdc.gov/bmi/adult-calculator/index.html
- NHLBI, BMI table — https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmi_tbl.htm
This calculator is educational and not medical advice. If you have a health condition, are pregnant, or are under 18, ask a clinician before changing your diet.
What the result tells you
A quick screening ratio of your weight to your height. It flags a category, but it doesn't measure body fat or health directly.
How to use it
- Read it alongside your waist measurement and how you feel day to day.
- Use it as a starting conversation with a professional, not a verdict.
- Re-check it after a real change in weight, not week to week.
Recommendations
- Muscle, frame size, age, and ethnicity all change how BMI should be read.
- A very muscular body can read 'overweight' while being lean and healthy.
- Raise any concern with a healthcare professional rather than acting on the number alone.
Health & wellbeing
BMI can be misleading in pregnancy, in older adults, and in very muscular or very lean bodies. Don't use it to judge your worth or chase a number.
Troubleshooting
Result seems wrong? Check that height and weight are in the right units. Adult categories don't apply to children or teens.
How it’s calculated
Body mass index compares weight to height. Adult categories follow the World Health Organization.
BMI = weight(kg) ÷ height(m)².
Under 18.5 underweight · 18.5–24.9 healthy · 25–29.9 overweight · 30+ obese.
Source: World Health Organization, Obesity and overweight fact sheet.
Common questions
Does BMI work for athletes?
Poorly. Muscle is denser than fat, so trained people often read "overweight" at a healthy body fat level. Use the body fat calculator instead.
Is a "healthy" BMI always healthy?
No. Normal-weight adults with a large waist or low muscle mass can still carry metabolic risk.