BMI calculator
Your body mass index, the category it falls in, and the weight range that goes with your height.
Your BMI
22.7
Healthy weight
- Healthy range 126 lb to 169 lb
- Healthy weight: BMI 18.5 to 24.9
At 5 ft 9 in and 154 lb, your BMI is 22.7, in the healthy weight range (18.5 to 24.9).
For your height, the healthy weight range (BMI 18.5 to 24.9) is 126 lb to 169 lb.
I’m not a doctor or a dietitian. This is an estimate, for information only. For decisions about your health, check with a professional.
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BMI categories at your height
| Category | BMI | Weight at your height |
|---|---|---|
| Underweight | under 18.5 | under 126 lb |
| Healthy weight (you) | 18.5 to 24.9 | 126 lb to 169 lb |
| Overweight | 25 to 29.9 | 170 lb to 203 lb |
| Class 1 obesity | 30 to 34.9 | 204 lb to 237 lb |
| Class 2 obesity | 35 to 39.9 | 238 lb to 270 lb |
| Class 3 obesity | 40 or more | 271 lb or more |
In short: BMI is your weight in kilograms divided by your height in meters squared. For adults, 18.5 to 24.9 is a healthy weight, 25 to 29.9 overweight and 30 or more obesity.
How it works
- BMI = weight in kilograms ÷ height in meters squared. In pounds and inches it’s the same number: weight in pounds ÷ height in inches squared × 703.
- The adult categories are the same for men and women: under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight, 30 and over obesity, split into class 1 (30 to 34.9), class 2 (35 to 39.9) and class 3 (40 and over).
- The healthy weight range for your height is the weight that gives a BMI from 18.5 up to just under 25. The number is rounded so it never crosses into the next category: 24.97 shows as 24.9.
Worked example
5 ft 9 in (69 in) and 154 lb: 154 ÷ 69² × 703 = 154 ÷ 4,761 × 703 = 22.7, healthy weight. In metric, 69.85 kg ÷ 1.7526² = 22.7. For 5 ft 9 in, a BMI of 18.5 is 125.3 lb and 25 is 169.3 lb, so the healthy range is 126 to 169 lb. The WHO’s own example, 70 kg and 1.75 m, gives 22.9.
Sources
- CDC: Adult BMI categories
- CDC: BMI frequently asked questions (formula and limits)
- CDC: Child and teen BMI categories
- WHO: Obesity and overweight, fact sheet
- WHO: Moderate and severe thinness, underweight, overweight (cut-offs)
- NHS: Overweight and obesity in adults, BMI ranges (UK)
- NHS: BMI calculator for adults (UK)
Text checked on September 30, 2026
Good to know
- BMI can’t tell muscle from fat, and it doesn’t show where fat sits on your body. Someone with a lot of muscle can come out overweight without much body fat.
- It’s a screening number, not a diagnosis: the CDC calls it one potential health indicator, to be considered with other factors. The WHO adds that measurements like waist size help.
- For people with a South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, the NHS uses lower cut-offs: overweight from 23 and obesity from 27.5.
- It isn’t used during pregnancy, and under 20 it’s read on growth charts by age and sex instead of with these categories.
Frequently asked questions
What is a healthy BMI?
For adults, 18.5 to 24.9 is what the CDC calls healthy weight and the WHO normal weight. Under 18.5 is underweight, 25 to 29.9 overweight and 30 or more obesity. The range above turns that into pounds for your height.
Is BMI accurate if I’m muscular?
Not very. The CDC notes that people with a lot of muscle can have a BMI in the overweight or even obesity category, because BMI can’t tell fat from muscle and bone. A body fat estimate or a waist measurement tells you more.
How do you calculate BMI in pounds and inches?
Divide your weight in pounds by your height in inches squared, then multiply by 703. For 154 lb at 5 ft 9 in (69 in): 154 ÷ 4,761 × 703 = 22.7.
Does BMI work for children and teens?
Not with the adult categories. From ages 2 through 19, the CDC compares a child’s BMI with others of the same age and sex on growth charts, as a percentile. This page shows the number but not an adult category under 18; a pediatrician can read the chart.
Why does the NHS use different cut-offs for some people?
Because people from Asian, Black African, African-Caribbean and Middle Eastern backgrounds have a higher chance of health problems at a lower BMI. For them, the NHS counts 23 to 27.4 as overweight and 27.5 or more as obesity.
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A full example, step by step
Take an adult who is 1.65 m (about 5 ft 5 in) tall, weighs 82 kg (about 181 lb) and has a waist of 92 cm.
- BMI: 1.65 × 1.65 = 2.7225, and 82 ÷ 2.7225 = 30.1. That falls in class 1 obesity (30 to 34.9).
- Top of the healthy range: 24.9 × 2.7225 = 67.8 kg. The bottom, 18.5 × 2.7225, is 50.4 kg.
- A first goal: 5% of 82 kg is 4.1 kg. At 77.9 kg the BMI is 28.6, still overweight, but the CDC notes that a 5% loss can already improve blood pressure, cholesterol and blood sugar.
- Waist-to-height ratio: 92 ÷ 165 = 0.56, which NICE classes as increased central fat (see below).
The same check in stones: 5 ft 6 in (66 in) and 12 st 4 lb (172 lb) gives 172 ÷ 4,356 × 703 = 27.8. For most adults that is overweight; under the lower NHS cut-offs for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean background, 27.5 or more already counts as obesity.
Add the waist: the second number doctors look at
BMI says nothing about where fat sits. The UK’s National Institute for Health and Care Excellence (NICE) uses the waist-to-height ratio alongside it for adults with a BMI under 35:
- 0.4 to 0.49: healthy, no increased health risk.
- 0.5 to 0.59: increased central fat, with increased health risks.
- 0.6 or more: high central fat, with further increased risks such as type 2 diabetes, high blood pressure and heart disease.
To measure it the way NICE describes: find the bottom of your ribs and the top of your hips, wrap the tape midway between them (just above the belly button), breathe out naturally and read the number. Use the same unit for waist and height, then divide. The simple target, in NICE’s words, is to keep your waist “to less than half their height”. The ratio works for both sexes, all ethnicities and people with a lot of muscle, which is where BMI is weakest.
When the BMI category can mislead
- Muscular builds: NICE says to interpret BMI with caution in adults with high muscle mass. The waist ratio is the better check there.
- Age 65 and over: NICE asks clinicians to read BMI with caution, considering other illnesses, physical function and the possible protective effect of a slightly higher BMI in older age.
- Pregnancy: the adult categories don’t apply.
- Under 20: BMI is compared with children of the same age and sex on growth charts, not with the adult bands.
- BMI of 35 or more: NICE does not use the waist ratio at that level; the BMI class already shows a high risk.
What to do with your result
- In the UK: the NHS suggests a non-urgent GP appointment if your BMI is overweight or obese and you want help losing weight, your waist is more than half your height, or you have prediabetes, diabetes, high blood pressure, high cholesterol, joint pain or sleep apnoea. You can self-refer to some weight management programmes. If you’re 40 to 74 without heart disease, diabetes or a past stroke, the free NHS Health Check every 5 years measures your BMI, waist and blood pressure.
- In the US: Medicare Part B covers obesity screening and behavioral counseling with a primary care provider for people with a BMI of 30 or more, at no cost if the provider accepts assignment.
- If your BMI is low: the NHS advises seeing a GP if you’ve lost weight suddenly or without changing what you eat or how active you are, because it can be a sign of an underlying condition.
Sources
- NICE NG246: Identifying and assessing overweight, obesity and central adiposity
- NHS: Obesity, BMI ranges, waist size and when to see a GP
- NHS: NHS Health Check
- NHS: Advice for underweight adults
- Medicare.gov: Obesity behavioral therapy
- CDC: Steps for losing weight (5% example)
More questions
What is a healthy waist-to-height ratio?
Under 0.5, meaning a waist less than half your height. NICE classes 0.5 to 0.59 as increased central fat and 0.6 or more as high, with higher risks of type 2 diabetes and heart disease.
Is BMI accurate for people over 65?
Less so. NICE advises reading BMI with caution from 65, taking other conditions into account, because a slightly higher BMI may be protective in older age. Your doctor can judge it with the rest of your health.
What BMI is considered underweight, and should I worry?
Under 18.5. The NHS advises seeing a GP if you’ve lost weight suddenly or without trying, because it can point to an underlying health condition.
Does Medicare pay for weight-loss counseling?
Yes, if your BMI is 30 or more: Part B covers screening and behavioral counseling with a primary care provider, and you pay nothing if the provider accepts assignment.