BMI Calculator
Calculate your Body Mass Index instantly with metric or imperial units. See your category, healthy weight range, and ideal weight. Private and free.
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BMI Result
BMI Categories (WHO Standard)
Medical disclaimer
BMI is a screening tool, not a diagnosis. A number from this calculator cannot tell you whether you are healthy, nor diagnose any condition. It does not replace a clinical assessment. Always speak to a doctor, registered dietitian, or other qualified healthcare professional before changing your diet, exercise, or medication based on a BMI result — especially if you are pregnant, an athlete, elderly, or managing a medical condition.
TL;DR
BMI = weight in kilograms divided by height in metres squared. The calculator above uses the WHO standard ranges (healthy = 18.5–24.9). If you are of Asian or South-Asian descent, the WHO recommends lower cut-offs — overweight starts at 23 and obesity at 27.5— because health risk rises at a lower BMI. BMI ignores muscle, so it over-flags muscular athletes and under-flags people who have lost muscle. Treat it as a starting point, then talk to a healthcare professional.
WHO standard vs. Asian BMI cut-offs
There is not one universal BMI chart. The familiar "25 is overweight" thresholds are the WHO international standard. But a 2004 WHO expert consultation found that people of Asian descent develop higher body-fat and metabolic risk (type 2 diabetes, cardiovascular disease) at a lower BMI, and recommended additional, lower trigger points for public-health action. Both sets are shown below.
| Category | WHO standard | WHO Asian / South-Asian |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Healthy weight | 18.5 – 24.9 | 18.5 – 22.9 |
| Overweight (increased risk) | 25.0 – 29.9 | 23.0 – 27.4 |
| Obese (high risk) | 30.0 and above | 27.5 and above |
The WHO retained 18.5, 23, 25, 27.5 and 30 as observation points rather than declaring new global categories, so different countries adopt them differently. India's national guidance, for example, treats a BMI of 23 and above as overweight. The calculator above reports the WHO standard category — read your number against the right-hand column if the Asian cut-offs apply to you.
Healthy weight range by height (WHO standard)
A "healthy weight" is a range, not a single number. The figures below are the weights that produce a BMI of 18.5 to 24.9 at each height — rounded to the nearest unit. Find your height, and your target band is the weight column.
| Height | Healthy range (kg) | Healthy range (lb) |
|---|---|---|
| 150 cm (4'11") | 42 – 56 kg | 92 – 124 lb |
| 155 cm (5'1") | 44 – 60 kg | 98 – 132 lb |
| 160 cm (5'3") | 47 – 64 kg | 104 – 141 lb |
| 165 cm (5'5") | 50 – 68 kg | 111 – 149 lb |
| 170 cm (5'7") | 53 – 72 kg | 118 – 159 lb |
| 175 cm (5'9") | 57 – 76 kg | 125 – 168 lb |
| 180 cm (5'11") | 60 – 81 kg | 132 – 178 lb |
| 185 cm (6'1") | 63 – 85 kg | 140 – 188 lb |
| 190 cm (6'3") | 67 – 90 kg | 147 – 198 lb |
The calculator above prints this range precisely for your exact height. If the Asian cut-offs apply to you, your upper limit is the weight at BMI 22.9 — roughly 8–9% lower than the upper number shown here.
When BMI is misleading
BMI uses only height and weight. It cannot see what your weight is made of, where fat sits on your body, or how dense your bones are. For these groups the number is unreliable and should not be read at face value:
- Athletes and muscular builds — muscle is denser than fat, so a fit rugby player or weightlifter can land in the "overweight" or "obese" band while carrying very little fat. BMI over-flags them.
- Older adults — people tend to lose muscle and bone with age (sarcopenia). A "normal" BMI can mask too little muscle and too much fat. Some research suggests a slightly higher BMI is protective in the elderly.
- Pregnant and breastfeeding people — standard BMI does not apply during pregnancy. Weight gain is expected and is tracked against pre-pregnancy weight by a clinician, not by this calculator.
- Children and teenagers — growing bodies use age-and-sex BMI percentiles (growth charts), not the adult categories above. Do not apply this tool to anyone under 18.
- Ethnicity and fat distribution — at the same BMI, body-fat percentage and where fat is stored (belly fat carries more risk) vary by ancestry, which is why the Asian cut-offs exist.
A fuller picture combines BMI with waist circumference(a proxy for abdominal fat), waist-to-height ratio, body-fat percentage, blood pressure, and blood-sugar and cholesterol readings — the measurements your doctor actually uses.
How this calculator works
The core formula is the Quetelet index, in use since the 1830s and adopted by the WHO: BMI = weight (kg) ÷ height (m)². In imperial units the equivalent is weight (lb) ÷ height (in)² × 703. This tool converts your imperial entries to metric internally, so both unit modes give the same result for the same body.
It also reports a healthy weight range (the weights that fall between BMI 18.5 and 24.9 for your height) and an ideal weightusing the Devine formula — 50 kg for men or 45.5 kg for women, plus 2.3 kg for every inch above 5 feet. Devine was created in the 1970s for medication dosing, not as a health target, so treat it as a rough reference rather than a goal to chase.
Everything runs in your browser. Your height and weight are never sent to a server — nothing leaves your device.
Frequently asked questions
What is a healthy BMI?
Under the WHO international standard, a BMI of 18.5 to 24.9 is the healthy range for most adults. If you are of Asian or South-Asian descent, the WHO uses a narrower healthy range of 18.5 to 22.9 because health risk climbs at a lower BMI. A healthy BMI is one input, not a verdict — your doctor weighs it alongside waist size, blood pressure, and blood tests.
Why are the BMI cut-offs lower for Asians and South Asians?
A 2004 WHO expert consultation found that people of Asian descent tend to have a higher body-fat percentage and greater risk of type 2 diabetes and cardiovascular disease at the same BMI as other populations. So the WHO added lower observation points: overweight from 23 and obesity from 27.5. Several countries, including India, build national guidance around these numbers.
Is BMI accurate for athletes and muscular people?
Often no. BMI cannot tell muscle from fat, and muscle is heavier for its size, so a lean, muscular person can score "overweight" or even "obese" while carrying very little fat. If you train seriously with weights, read your BMI alongside a body-fat measurement and waist circumference rather than on its own.
Can I use this BMI calculator during pregnancy?
No. Standard BMI categories do not apply during pregnancy, when weight gain is normal and expected. Clinicians track gestational weight gain against your pre-pregnancy weight using separate guidance. If you are pregnant, follow the advice of your midwife or obstetrician, not this tool.
Is BMI the same for men and women?
The BMI formula and the WHO categories are identical for men and women — the calculation uses only height and weight. Sex does affect typical body-fat percentage at a given BMI (women usually carry more body fat than men at the same BMI), which is one reason BMI alone is an incomplete measure. The gender option above only changes the optional Devine ideal-weight estimate.
Does a normal BMI mean I am healthy?
Not necessarily. A normal BMI can hide low muscle mass, high abdominal fat, or poor metabolic markers — sometimes described as "normal weight obesity." BMI is a population-level screening tool, not a personal health check. For an accurate picture of your health, see a healthcare professional who can assess waist circumference, body composition, and blood work.