BMI Calculator
Body Mass Index from your height and weight
Enter your height and weight to get your Body Mass Index (BMI) and where it falls — a quick screening of whether your weight is in a healthy range for your height.
What BMI measures
BMI is weight relative to height squared. In imperial units it is 703 × pounds ÷ inches²; in metric it is simply kg ÷ m².
| BMI | Category | At 5′10″ |
|---|---|---|
| Under 18.5 | Underweight | Under 129 lb |
| 18.5 to 24.9 | Normal weight | 129 to 174 lb |
| 25 to 29.9 | Overweight | 175 to 209 lb |
| 30 and over | Obese | 210 lb and over |
BMI is a screening tool, not a diagnosis. It does not measure body fat, health or fitness. Nothing on this page is medical advice; discuss any concern with a clinician who can assess you in context.
BMI chart by height and weight
| Height | 140 lb | 160 lb | 180 lb | 200 lb | 220 lb |
|---|---|---|---|---|---|
| 5′2″ | 25.6 | 29.3 | 32.9 | 36.6 | 40.2 |
| 5′6″ | 22.6 | 25.8 | 29.0 | 32.3 | 35.5 |
| 5′10″ | 20.1 | 23.0 | 25.8 | 28.7 | 31.6 |
| 6′0″ | 19.0 | 21.7 | 24.4 | 27.1 | 29.8 |
| 6′2″ | 18.0 | 20.5 | 23.1 | 25.7 | 28.2 |
The same 180 lb is a BMI of 32.9 at 5′2″ and 23.1 at 6′2″. Height matters enormously because it is squared, which is also the source of one of the formula's known distortions.
What BMI cannot see
BMI uses two numbers and ignores everything else. The specific consequences are well documented:
- It cannot distinguish muscle from fat. Muscle is denser, so athletes and heavily trained people routinely land in the "overweight" or "obese" range while carrying low body fat.
- It misses muscle loss in older adults. Someone can lose muscle and gain fat with no change in weight, and their BMI will not move at all.
- It ignores fat distribution. Abdominal fat carries more metabolic risk than fat elsewhere, and BMI treats them identically.
- The squared term distorts at the extremes. Height scales roughly with the cube of volume, not the square, so BMI tends to read high for very tall people and low for very short ones.
- The thresholds were derived largely from European populations. Some health bodies use lower cut-offs for people of South Asian descent, where metabolic risk appears at a lower BMI.
- It does not apply to children and teenagers, who use age- and sex-specific percentile charts, nor to pregnancy.
Measurements that add what BMI misses
| Measure | Adds | Rough guidance |
|---|---|---|
| Waist circumference | Where fat is stored | Risk rises above 40″ men, 35″ women |
| Waist-to-height ratio | Scales with body size | Keep waist under half your height |
| Body fat percentage | Fat against lean mass | Method-dependent, see that page |
| Waist-to-hip ratio | Fat distribution pattern | Used in some risk models |
Waist-to-height is the most useful single addition because it needs only a tape measure and no reference table: keeping your waist below half your height is a memorable rule that captures abdominal fat, which BMI cannot.
Using it sensibly
BMI is a free, instant, population-level screen. That is genuinely useful, and it is all it is. Where it is most informative for an individual is as a trend: a reading moving steadily in one direction over months says more than a single number compared to a threshold.
If your BMI sits outside the normal range and you want to know what it means for you specifically, that is a conversation with a clinician who can weigh it against your body composition, family history, blood work and activity. A calculator cannot do that, and this one is not trying to.
How this bmi calculator works out its numbers
BMI is 703 × weight (lb) ÷ height (in)², the standard imperial form of kg ÷ m². Categories follow the World Health Organization adult classification.
- Adults only. Children and teenagers require age- and sex-specific percentile charts, and BMI is not applicable during pregnancy.
- No body composition. The formula takes height and weight and nothing else, so it cannot separate muscle from fat, cannot see fat distribution, and cannot detect muscle loss at stable weight.
- The squared height term is an approximation. Body mass scales closer to the cube of height, which is why BMI tends to read high for very tall people and low for very short ones.
- Thresholds are population-derived, largely from European cohorts. Some health authorities apply lower cut-offs for South Asian populations.
- Screening, not diagnosis. Nothing here is medical advice. A BMI reading outside the normal range is a prompt to speak to a clinician, not a conclusion.
Reviewed September 2026.
Figures reviewed . Every worked example on this page is checked against the calculator above.
BMI Calculator: frequently asked questions
How is BMI calculated?
703 × weight in pounds ÷ height in inches squared, or weight in kilograms ÷ height in metres squared. A 170 lb person at 5'10" has a BMI of 24.4.
What is a healthy BMI?
18.5 to 24.9 is the standard adult range. At 5'10" that is roughly 129 to 174 lb. It is a population screening range rather than an individual target.
Is BMI accurate?
It is a reasonable population-level screen and an imperfect individual measure. It cannot distinguish muscle from fat, misses muscle loss in older adults, and ignores where fat is stored — all of which matter more to health than the ratio itself.
Why is my BMI high if I'm muscular?
Because muscle is denser than fat and BMI only sees total weight. Well-trained athletes frequently register as overweight or obese while carrying low body fat. Body fat percentage or waist measurement is more informative in that case.
What is a healthy BMI for my age?
The 18.5 to 24.9 range applies to most adults regardless of age, though some research suggests slightly higher may carry no additional risk in older adults. Children and teenagers use age- and sex-specific percentile charts instead.
Does BMI differ for men and women?
No, the formula and thresholds are the same. That is itself a limitation, since men and women differ systematically in body composition at the same BMI.
What is better than BMI?
Waist circumference and waist-to-height ratio both capture abdominal fat, which BMI cannot see. Keeping your waist under half your height is a simple rule needing only a tape measure. Body fat percentage adds the fat-versus-lean picture.
Is BMI valid for all ethnicities?
The thresholds were derived largely from European populations. Some health bodies use lower cut-offs for people of South Asian descent, where metabolic risk appears at a lower BMI. Ask a clinician what applies to you.