Kalkulo

BMI calculator

Work out your body mass index from height and weight and see your CDC category: underweight, healthy, overweight or obesity class 1-3.

Result
22.9
Normal
152540

About this tool

Why use this tool

Body Mass Index (BMI) is a quick screening indicator used by the CDC, NIH and American Heart Association to flag whether your weight falls within a healthy range for your height. It is a starting point to assess the risk of type 2 diabetes, heart disease, stroke and hypertension linked to overweight or obesity — conditions that affect over 40 % of American adults.

How the calculation works

The imperial formula is: BMI = (weight in pounds × 703) ÷ height in inches². CDC thresholds for adults 20+: under 18.5 = underweight, 18.5–24.9 = healthy weight, 25.0–29.9 = overweight, 30.0–34.9 = obesity class 1, 35.0–39.9 = class 2, 40+ = class 3 (severe obesity). For children and teens, the CDC uses age- and sex-specific percentile charts instead.

Real example

A person 5'8" (68 in) weighing 165 lbs has a BMI of (165 × 703) ÷ (68 × 68) = 25.1. According to CDC criteria they fall just into the overweight range. Dropping to 160 lbs would move them back into the healthy range at BMI 24.3.

Practical tips

BMI does not distinguish fat from muscle nor measure abdominal fat. Combine it with waist circumference (increased risk above 35 in for women and 40 in for men per NIH). Follow the Dietary Guidelines for Americans (USDA MyPlate) and CDC's 150 minutes/week of moderate aerobic activity. Talk to your primary care provider or a Registered Dietitian Nutritionist (RDN) for personalised guidance. Most insurance plans cover annual wellness visits at no cost under the ACA.

Disclaimer

This tool provides an estimate for general information only. It is not a diagnostic tool and should not replace advice from a licensed healthcare provider. BMI is less reliable for athletes with high muscle mass, pregnant women, older adults, and people of certain ethnicities where risk thresholds may differ.

Frequently asked questions

How accurate is BMI for athletes and bodybuilders?⌄
BMI is notoriously inaccurate for athletes because it cannot distinguish between fat and muscle — both contribute equally to weight. A bodybuilder with 8% body fat may have a BMI of 28, technically classified as overweight. The CDC acknowledges this limitation and recommends complementary measurements like body fat percentage, waist circumference, or DEXA scans for athletic populations.
What BMI is considered healthy for Asian Americans?⌄
Research shows that Asian Americans face elevated health risks at lower BMI thresholds than white Americans. The World Health Organization suggests using lower cut-off points for Asian populations: overweight at BMI 23+ and obese at BMI 27.5+, compared to 25 and 30 for general populations. This reflects differences in body fat distribution and associated disease risk at similar BMI levels.
How does BMI relate to life expectancy?⌄
Large-scale studies show that both very low BMI (below 18.5) and high BMI (above 30) are associated with reduced life expectancy. The lowest mortality risk is generally found at BMI 20-25. However, fitness level is a stronger predictor of longevity than BMI alone — an overweight person who exercises regularly often has better health outcomes than a normal-weight sedentary person.
Can BMI be misleading for older adults?⌄
Yes, BMI tends to underestimate body fat in older adults because muscle mass naturally declines with age while fat mass may stay the same or increase. A 70-year-old with a normal BMI of 23 may have much higher body fat than a 30-year-old with the same BMI. Geriatric specialists often recommend accepting slightly higher BMI ranges in elderly patients to protect against frailty and falls.
What is the relationship between BMI and type 2 diabetes risk?⌄
The risk of developing type 2 diabetes increases substantially with BMI above 25, and dramatically above 30. Studies show that each unit increase in BMI above 22 raises diabetes risk by approximately 20%. Losing just 5-7% of body weight significantly reduces diabetes risk in at-risk individuals, as demonstrated by the landmark Diabetes Prevention Program study.

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