BMI Calculator for Adults — Body Mass Index & Healthy Weight
Calculate your Body Mass Index (BMI) from height and weight, see your adult BMI category and healthy-weight range, and compare BMI Prime, the New Oxford BMI and the Ponderal Index — with the lower WHO action points used for Asian populations.
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1.3 × weight ÷ height2.5 (Trefethen)
Weight ÷ height³ (kg/m³)
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Adult BMI Categories: WHO Standard vs Asian Action Points
WHO adult classification, with the additional public-health action points a 2004 WHO expert consultation proposed for Asian populations.
| BMI (kg/m²) | WHO Standard Category | Asian Populations (WHO 2004) |
|---|---|---|
| Below 18.5 | Underweight | Underweight |
| 18.5 – 22.9 | Healthy weight | Increasing but acceptable risk |
| 23.0 – 24.9 | Healthy weight | Increased risk |
| 25.0 – 27.4 | Overweight | Increased risk |
| 27.5 – 29.9 | Overweight | High risk |
| 30.0 – 34.9 | Obesity class I | High risk |
| 35.0 – 39.9 | Obesity class II | High risk |
| 40.0 or above | Obesity class III | High risk |
Children & Teens (Ages 2–19)
Adult categories don't apply to children and teenagers, because body composition changes with age and puberty. The CDC uses BMI-for-age percentiles compared with children of the same age and sex:
- Underweight: below the 5th percentile
- Healthy weight: 5th to below the 85th percentile
- Overweight: 85th to below the 95th percentile
- Obesity: 95th percentile or above
Limits of BMI
- Muscle vs fat: muscular people, including bodybuilders and athletes, can have a high BMI without excess body fat. See the section below.
- Older adults: muscle loss with age can hide excess fat at a "normal" BMI.
- Fat distribution: BMI doesn't show fat stored around the organs — waist measurements help.
- Pregnancy: adult BMI categories don't apply during pregnancy.
BMI for bodybuilders and athletes
BMI uses only weight and height, so it treats muscle and fat as the same thing. A bodybuilder or field athlete can land in the overweight or obesity range with a low body-fat percentage. That is a known limit of the measure, not a different BMI formula.
Example: an adult at 5 ft 10 in (1.78 m) and 200 lb (90.7 kg) has a BMI of 28.7, which is in the standard overweight range. If a tape or caliper estimate puts body fat near 12%, the high BMI is mostly lean mass. BMI cannot show that. A waist measurement or a body-fat estimate can.
Use this page for the screening number. If the result looks high and you train with weights, check it against the body fat calculator or the waist-to-height ratio calculator. CDC and WHO still use standard adult BMI categories for population screening. They do not publish a separate athletic cut-off.
What is BMI?
Body Mass Index (BMI) is a number calculated from a person's weight and height. It is commonly used as a screening measure to group adult weight status. BMI does not directly measure body fat and should be considered alongside other health information.
How to calculate BMI
BMI = weight (kg) ÷ height (m)², or with imperial units BMI = 703 × weight (lb) ÷ height (in)².
- BMI Prime = BMI ÷ 25 — your BMI as a fraction of the upper limit of the healthy range (1.0 = the overweight threshold).
- New Oxford BMI = 1.3 × weight (kg) ÷ height (m)2.5 — an alternative proposed by Oxford mathematician Nick Trefethen to reduce the way standard BMI overstates tall people and understates short people. It is not an official clinical standard.
- Ponderal Index = weight (kg) ÷ height (m)³ — scales with height cubed; mainly used for newborns and very tall or short people.
By Suhaib Hassan · Reviewed 4 October 2026 against CDC, NIH and WHO sources · How CalculatePilot verifies formulas →
BMI categories for adults
For standard adult screening, the commonly used categories are: below 18.5 underweight; 18.5–24.9 healthy weight; 25.0–29.9 overweight; 30.0 or above obesity. These categories are screening ranges. A BMI result should not be treated as a diagnosis or as a complete assessment of an individual's health.
What does your BMI result mean?
A BMI result can help provide a quick starting point for discussing weight and health. It does not account for muscle mass, body composition, bone density, fat distribution, medical history, physical activity, sleep, or laboratory findings. Someone with substantial muscle mass, for example, may have a higher BMI without having the same body-fat pattern as another person with the same BMI.
For adults, waist circumference and other health measures can provide additional information about body-fat distribution and health risk — try the waist-to-height ratio calculator or the body fat calculator.
Worked BMI example
For an adult who is 5'7" (67 inches) and weighs 160 lb, the imperial calculation is (160 ÷ 67²) × 703, which is approximately 25.1. That result falls in the standard adult overweight screening category — and in the "increased risk" band of the WHO action points for Asian populations.
When to seek professional advice
If your BMI falls outside the healthy-weight range, or if you have concerns about your weight, body composition, or related health risks, discuss your individual circumstances with a doctor, registered dietitian, or other qualified healthcare professional. Medical information, not medical advice: this tool gives a general estimate for screening purposes and is not a diagnosis.
Sources
- CDC — Adult BMI Calculator and CDC — Adult BMI categories
- NHLBI / NIH — Calculate your BMI
- World Health Organization — Obesity and overweight
- WHO Expert Consultation. Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Lancet 2004;363:157–163.
- NHS — BMI calculator for adults
Frequently asked questions
What is a healthy BMI?
For standard adult screening, a BMI from 18.5 to 24.9 is commonly classified as healthy weight. This range is not a guarantee of health and does not replace an individual assessment.
Is BMI accurate for everyone?
No. BMI is a useful population and screening measure, but it cannot distinguish muscle from fat or show where fat is stored. It should be interpreted with other relevant health information.
Is there a BMI calculator for bodybuilders?
No. Bodybuilders use the same formula, weight divided by height squared. The difference is how you read it. A high BMI with a low waist and a low body-fat estimate usually means muscle, not the risk pattern BMI is meant to screen for. BMI is not a body-composition test.
Can I use this BMI calculator for children?
No. This page uses adult BMI categories. Children and teenagers need BMI-for-age assessment using age- and sex-specific growth references.
Does BMI diagnose obesity or another disease?
No. BMI is a screening measure. A healthcare professional can consider BMI together with medical history, physical findings, health behaviours and other relevant measurements.
How is the healthy-weight range calculated?
For a given height, the calculator applies the standard adult BMI range of 18.5 to 24.9 to estimate the corresponding weight range. It is an estimate based on BMI, not a personalized target weight.
Why are there lower BMI cut-offs for Asian populations?
A 2004 WHO expert consultation found that many Asian populations have more body fat and a higher risk of type 2 diabetes and cardiovascular disease at a given BMI than European populations. It kept the international categories but proposed public-health action points of 23 (increased risk) and 27.5 (high risk).
What is BMI Prime?
BMI Prime is your BMI divided by 25, the upper limit of the healthy range. A value below 1.0 is under the overweight threshold; for example, 1.2 means your BMI is 20% above it.
What is the New Oxford BMI?
It's an alternative formula, 1.3 × weight (kg) ÷ height (m) to the power 2.5, proposed by Oxford mathematician Nick Trefethen. It reduces the way standard BMI makes tall people look heavier and short people look lighter, but it is not used for official clinical categories.
What a BMI number measures and where it misleads: BMI calculator guide.
Next Steps After Your BMI
Build a fuller picture of body composition and energy needs.