BMI Calculator
Enter your height and weight to see your BMI, healthy weight and how you compare with US adults.
CDC adult categories. US comparison: CDC measurements of 5,929 adults, 2021–2023. Method and sources
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CDC NHANES 2021–2023, 5,929 adults measured; our calculation.
BMI (body mass index) is your weight in kilograms divided by your height in meters squared, or pounds × 703 ÷ inches². For adults 20 and over, CDC uses one scale for everyone: under 18.5 is underweight, 18.5 to 24.9 is a healthy weight, 25 to 29.9 is overweight and 30 or more is obesity.
- The healthy weight depends only on height: at 5′7″ (170.2 cm) it is 118 to 159 lb (54 to 72 kg).
- The median US adult has a BMI of 28.2, and 72.4% have a BMI of 25 or more (CDC measurements, 2021–2023).
- Obesity has three classes: 30 to 34.9, 35 to 39.9 and 40 or more.
- Under 20, BMI is read as a percentile for age and sex, not on this scale.
- BMI can’t tell muscle from fat, and it can’t show where fat sits; a waist measurement can.
Medical disclaimer: This calculator gives estimates for information only. BMI is a screening measure, not a diagnosis. Ask a healthcare professional for medical advice.
How to read your result
Every number below uses the calculator’s imperial starting values: 5′7″ (170.2 cm) and 160 lb (72.6 kg). That weight sits right on the line between two categories.
- BMI: 25.1, overweight
- 160 × 703 ÷ 67² = 25.1, rounded to one decimal; the category comes from that rounded number. At 159 lb the BMI would be 24.9, a healthy weight. The calculator shows the CDC category for adults, and below 17 the WHO thinness grades: moderate thinness from 16 to 16.9 and severe thinness under 16 (WHO, 1995).
- Healthy weight: 118–159 lb (54–72 kg)
- The lightest and heaviest whole pounds at your height with a BMI of 18.5 to 24.9, and the same in whole kilograms. It depends only on height. In imperial mode the tiles also show each limit converted (53.5 and 72.1 kg).
- 1 lb (0.5 kg) above the healthy range
- The distance from your weight to the nearest end of that range.
- Compared with US adults: higher than 28%
- The share of adults aged 20 and over, measured by CDC in 2021–2023, whose BMI is lower than yours. The result adds the figure for men alone (26%) and women alone (31%); the next section has the full table.
- BMI Prime: 1.00
- Your BMI divided by 25, where overweight starts. 1.00 means you’re at that line; under 1.00 is below it.
- Ponderal index: 14.7 kg/m³
- Weight in kilograms divided by height in meters cubed. CDC and WHO publish no adult cut-offs for it, so compare it only with your own earlier results.
- Weight milestones
- The weight where each range starts at your height. At 5′7″: healthy from 118 lb, overweight from 160 lb, obesity from 192 lb, class 2 obesity from 224 lb and class 3 from 256 lb.
- What-if table
- Your BMI after losing or gaining 5 to 20 lb (2.5 to 10 kg in metric). Five pounds lighter, at 155 lb, the example’s BMI is 24.3.
How your BMI compares with US adults
The comparison uses CDC’s measurements of 5,929 adults aged 20 and over (pregnant women excluded), taken from August 2021 to August 2023 in its National Health and Nutrition Examination Survey (NHANES). The middle adult had a BMI of 28.2, in the overweight range, and a quarter had a BMI of 24.5 or lower. The calculator ranks your result against these adults, then against men and women separately.
| Percentile | All adults | Men | Women |
|---|---|---|---|
| 5th | 20.1 | 20.9 | 19.7 |
| 10th | 21.9 | 22.3 | 21.5 |
| 25th | 24.5 | 24.9 | 24.1 |
| 50th | 28.2 | 28.2 | 28.3 |
| 75th | 33.3 | 32.6 | 34.4 |
| 90th | 39.5 | 37.8 | 40.9 |
| 95th | 43.7 | 42.1 | 44.9 |
Read a row as: 25% of US adults have a BMI of 24.5 or lower. Our calculation from CDC NHANES 2021–2023 measured heights and weights (5,929 adults: 2,680 men and 3,249 women, survey-weighted, pregnant women excluded); the same method reproduces NCHS’s published medians (28.2 for men, 28.3 for women) and means (29.4 and 30.0).
The spread is wider among women. A quarter of women have a BMI of 24.1 or lower and one in ten has 40.9 or more; for men the same points are 24.9 and 37.8. The US obesity statistics page has the trends since 1960 and the splits by age.
BMI categories for adults
For adults 20 and older, CDC bases the categories on BMI alone, “regardless of age, sex, or race”. Only about 1 in 4 US adults (26.0%) has a BMI in the healthy range; the last column shows how the rest are spread.
| Category | BMI | US adults |
|---|---|---|
| Underweight | Under 18.5 | 1.6% |
| Healthy weight | 18.5–24.9 | 26.0% |
| Overweight | 25–29.9 | 32.1% |
| Class 1 obesity | 30–34.9 | 20.6% |
| Class 2 obesity | 35–39.9 | 10.3% |
| Class 3 obesity | 40 or more | 9.4% |
Categories: CDC Adult BMI Categories. Shares: our calculation from CDC NHANES 2021–2023 (5,929 adults); they match NCHS’s published crude rates for underweight (Health E-Stat 119), overweight (Health E-Stat 111), obesity and class 3 obesity (Data Brief 508).
The BMI chart gives the weights for each category at every height, and there are charts for women and for men. BMI categories explained covers what each range means for health.
Healthy weight by height
The healthy range depends only on height and is the same for men and women. Overweight starts at the next pound (or kilogram) above it. Six heights below, 3 inches apart; the full BMI chart covers every inch from 4′10″ to 6′6″ and every 5 cm from 145 to 200 cm.
| Height | Healthy weightBMI 18.5–24.9 | Obesity fromBMI 30 |
|---|---|---|
| 5′0″152.4 cm | 95–127 lb43–57 kg | 154 lb70 kg |
| 5′3″160.0 cm | 105–140 lb48–63 kg | 170 lb77 kg |
| 5′6″167.6 cm | 115–154 lb52–70 kg | 186 lb85 kg |
| 5′9″175.3 cm | 125–168 lb57–76 kg | 203 lb92 kg |
| 6′0″182.9 cm | 137–183 lb62–83 kg | 221 lb101 kg |
| 6′3″190.5 cm | 148–199 lb67–90 kg | 240 lb109 kg |
Whole pounds and kilograms whose BMI, rounded to one decimal, falls in each range at the height shown; each unit is worked out on its own. Cut-offs: CDC Adult BMI Categories.
How to calculate BMI by hand
In pounds and inches, multiply your weight by 703 and divide by your height in inches squared. In metric, divide your weight in kilograms by your height in meters squared. Both formulas are CDC’s (Calculating BMI); 703 turns pounds per square inch into kilograms per square meter.
- US units: 160 lb at 5′7″ (67 in): 160 × 703 ÷ (67 × 67) = 112,480 ÷ 4,489 = 25.1.
- Metric: 70 kg at 170 cm (1.70 m): 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2.
- From centimeters: 70 ÷ 170 ÷ 170 × 10,000 = 24.2, the same result without converting to meters.
Round to one decimal before reading the category, as the calculator and the BMI charts do. The BMI formula guide explains where 703 comes from and the version Nick Trefethen proposed in 2013.
When BMI misleads
CDC calls BMI “a quick, safe, and reliable screening measure” and adds that it “does not distinguish between fat, muscle, and bone mass” (CDC). Four common cases:
- Muscle. A muscular person can have a BMI over 25 with little body fat. The body fat calculator estimates body fat from tape or skinfold measurements, and BMI for athletes goes further.
- Where fat sits. US guidelines treat a waist over 40 inches (102 cm) in men and 35 inches (88 cm) in women as a marker of higher risk, mainly at a BMI of 25 to 34.9 (NHLBI). The waist-to-height ratio is another check.
- Age. The cut-offs stay the same at every adult age, but body fat at a given BMI also depends on age, sex and ethnic group (Gallagher et al., 2000), so the same BMI can mean a different amount of fat at 25 and at 75. The body fat percentage chart shows typical body fat by age.
- Asian ancestry. A WHO expert consultation found that many Asian populations have higher risk at lower BMIs. It kept the international categories and identified BMI 23, 27.5, 32.5 and 37.5 as points for public-health action (WHO, 2004).
In 2025 the Lancet Commission on Clinical Obesity (58 experts, endorsed by 76 organizations) recommended confirming excess body fat with a body measurement such as waist size, or with a direct body-fat measurement, instead of diagnosing obesity from BMI alone. More in BMI limitations.
BMI for children and teens
Under 20, the same BMI means different things at different ages, so CDC reads it as a percentile on growth charts for age and sex. This calculator uses the adult scale; for ages 2 to 19, use the BMI calculator for children and teens.
| Category | BMI-for-age percentile |
|---|---|
| Underweight | Under the 5th |
| Healthy weight | 5th to under the 85th |
| Overweight | 85th to under the 95th |
| Obesity | 95th or above |
| Severe obesity | 120% of the 95th or more, or a BMI of 35 or more |
Source: CDC Child and Teen BMI Categories.
BMI and health
US guidelines link a BMI above the healthy range with higher risk of high blood pressure, type 2 diabetes, coronary heart disease, stroke, sleep apnea and osteoarthritis (NHLBI). In a large trial of adults with overweight or obesity and type 2 diabetes, losing 5 to 10% of body weight was linked to better blood sugar, blood pressure, HDL cholesterol and triglycerides after one year (Wing et al., 2011).
CDC notes that “poor nutrition and underlying health conditions can result in underweight” (Health E-Stat 119); if your BMI is under 18.5 and you don’t know why, ask a doctor. For one person, CDC says BMI “should be considered with other factors”, such as blood pressure and cholesterol. The evidence behind each risk is in BMI and health risks.
Common situations
You want a version for women or men
The cut-offs are the same for everyone. The BMI calculator for women and the one for men add the waist cut-off for each sex and US data for women or men.
You’re 65 or older
The categories don’t change. The BMI calculator by age adds the research on BMI and survival in adults 65 and over.
You lift weights or play a power sport
Muscle can push BMI past 25. A waist measurement and a tape or skinfold estimate from the body fat calculator can suggest whether the extra weight is fat.
You want one target weight
The healthy range is every weight with a BMI of 18.5 to 24.9 at your height. The ideal weight calculator shows the single weights that four published formulas give.
You use kilograms and centimeters
Switch the calculator to Metric. Results then show kilograms first, pounds second, and the healthy range in whole kilograms.
You want to lower your BMI
The what-if table shows your BMI at each 5 lb (2.5 kg) step. NIH’s Body Weight Planner builds a calorie and physical activity plan for a goal weight, for adults who aren’t pregnant or breastfeeding. More in how to lower your BMI.
Frequently asked questions
For adults 20 and over there is one healthy range at every age: 18.5 to 24.9. CDC applies its adult categories “regardless of age, sex, or race” (CDC). Under 20, BMI is read as a percentile for age and sex instead; use the BMI calculator for children and teens. Body composition does change: body fat at a given BMI depends on age and sex (Gallagher et al., 2000). In adults 65 and over, a meta-analysis of 197,940 people found that the risk of death rose below a BMI of 23 and above 33 (Winter et al., 2014), an association rather than a target. The BMI calculator by age has more on adults 65 and over.
24.2, a healthy weight: 70 ÷ (1.70 × 1.70) = 70 ÷ 2.89 = 24.2. At 170 cm the healthy range is 54 to 72 kg (118 to 158 lb), so 70 kg sits 2 kg below its top. Among US adults, a BMI of 24.2 is higher than about 22% (our calculation from CDC measurements, 2021–2023).
No. A BMI of 23 is in the healthy weight range (18.5 to 24.9), 2 points below where overweight starts; at 5′6″ (167.6 cm) it’s about 143 lb (65 kg). About 84% of US adults have a higher BMI (our calculation from CDC measurements, 2021–2023). BMI can’t show how much of your weight is fat: the body fat calculator estimates that, and a waist measurement shows where fat sits.
There isn’t one. CDC’s adult categories are unchanged: under 18.5 underweight, 18.5 to 24.9 healthy weight, 25 to 29.9 overweight and 30 or more obesity, in classes 1 to 3 (CDC). What changed in 2025 is advice on diagnosis: the Lancet Commission on Clinical Obesity recommended confirming excess body fat with a waist measurement or a direct body-fat measurement instead of diagnosing obesity from BMI alone. The “new BMI” formula some sites show is Nick Trefethen’s 2013 proposal; CDC and WHO still use the standard formula (see the new BMI calculator).
18.5 to 24.9, which CDC calls a healthy weight. It’s the same for men and women at every adult age. At 5′4″ (162.6 cm) that’s 108 to 145 lb (49 to 65 kg); at 5′10″ (177.8 cm), 129 to 173 lb (59 to 78 kg). The healthy BMI range guide covers the range in more depth.
The formula and the cut-offs are the same. Bodies differ: body fat at a given BMI depends on sex (Gallagher et al., 2000), and in CDC’s body scans the average woman aged 20 to 59 had 38.7% body fat against 27.2% for the average man (our analysis of NHANES 2011–2018). US distributions differ too: the median BMI is 28.2 for men and 28.3 for women, but 1 in 10 women has a BMI of 40.9 or more, against 37.8 for men. The calculators for women and for men add the waist cut-off for each sex.
No. BMI is a ratio in kilograms per square meter, so a BMI of 25 means 25 kg/m², not 25%. Body fat percentage is a different measure: the share of your weight that is fat, which the body fat calculator estimates. The only percentage this calculator shows is your rank, the share of US adults with a lower BMI than yours.
The number is exact for the height and weight you enter. As a measure of body fat it’s indirect: CDC notes that BMI “does not directly measure body fat” and “does not distinguish between fat, muscle, and bone mass”, though it is moderately to strongly associated with other measures of body fat (CDC). For one person, CDC says BMI “should be considered with other factors”, such as blood pressure and cholesterol. A waist measurement is the simplest check to add (see when BMI misleads).
Sources and method
Written by Marko Visic, MPharm. “Our calculation” means we computed the figure from CDC’s public survey files with the method below.
- CDC. Adult BMI Categories: the cut-offs used by the calculator and the tables.
- CDC. Child and Teen BMI Categories: percentiles for ages 2 to 19.
- CDC. Calculating BMI: the formulas in US and metric units.
- CDC. About Body Mass Index (BMI): what BMI measures and what it misses.
- CDC NHANES August 2021–August 2023 exam files (DEMO_L, BMX_L): our calculation of BMI percentiles and category shares for adults aged 20 and over (5,929: 2,680 men, 3,249 women), weighted with the exam weights, pregnant women excluded.
- Fryar CD, Afful J, Saif NT. NCHS Health E-Stat 111 (Feb 2026): overweight and obesity in US adults, August 2021–August 2023.
- Emmerich SD, et al. NCHS Data Brief No. 508 (Sep 2024): obesity and severe obesity in US adults, August 2021–August 2023.
- Ansai N, Fryar CD, Afful J. NCHS Health E-Stat 119 (Jun 2026): underweight in US adults, August 2021–August 2023.
- CDC NCHS. Vital and Health Statistics Series 3, No. 50: median and mean BMI of US men and women.
- CDC NHANES 2011–2018 DXA body scans: our analysis of average body fat by sex, ages 20 to 59 (body fat percentage chart).
- NHLBI. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults (NIH, 1998): waist cut-offs and conditions linked to excess weight.
- WHO Expert Consultation. The Lancet, 2004: BMI in Asian populations and the public-health action points.
- Trefethen N. New BMI (University of Oxford): the 2013 proposal some sites call the “new BMI”.
- WHO. Physical status: the use and interpretation of anthropometry (Technical Report Series 854, 1995): thinness grades.
- Rubino F, et al. Lancet Diabetes & Endocrinology, 2025: definition and diagnostic criteria of clinical obesity.
- Wing RR, et al. Diabetes Care, 2011: weight loss and cardiovascular risk factors after one year (Look AHEAD).
- NIDDK. Body Weight Planner: calorie and physical activity plans for a goal weight, adults only.
- Winter JE, et al. American Journal of Clinical Nutrition, 2014: BMI and mortality in adults 65 and over.
- Gallagher D, et al. American Journal of Clinical Nutrition, 2000: body fat predicted from BMI, sex, age and ethnic group.
Method. BMI = weight (kg) ÷ height (m)², or lb × 703 ÷ in², rounded to one decimal; the category uses the rounded value. Metric input is computed in kg/m², US input with 703. Healthy limits are the lightest and heaviest whole pounds (or kilograms) whose rounded BMI is 18.5 to 24.9, each unit worked out on its own. The rank is the share of adults with a lower BMI (and, for “lower than”, the share with a higher one), read from the survey-weighted distribution of measured BMI, which CDC records to one decimal (1st to 99th percentile, linear interpolation between them); adults with the same BMI count on neither side. The category shares reproduce NCHS’s published crude rates: underweight 1.6%, overweight 32.1%, obesity 40.3%, class 3 obesity 9.4%. Data: CDC NHANES August 2021–August 2023.