BMI Calculator
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- BMI
- Category
Note: BMI is a screening tool, not a diagnostic measure. Results do not constitute medical advice. Consult a licensed healthcare professional for personalised guidance.
Formula
Metric: BMI = weight_kg ÷ height_m² | Imperial: BMI = 703 × weight_lb ÷ height_in²Worked Example
Inputs
- Weight
- 70.00 kg
- Height
- 175.00 cm (1.75 m)
- Unit System
- Metric
Result
- BMI
- 22.86
- Category (CDC adult standard)
- normal
A weight of 70.00kg and height of 175.00cm gives a BMI of 22.86, which falls in the normal range according to CDC adult standards. This result is for informational purposes only. BMI is a screening tool, not a diagnostic measure. Consult a qualified healthcare professional for personal health decisions.
Frequently Asked Questions
- What is BMI and what does it measure?
- Body Mass Index (BMI) is a screening tool calculated from weight and height. It is used to assess whether a person is underweight, normal weight, overweight, or obese. BMI does not directly measure body fat — it is a proxy measure. The formula is weight (kg) ÷ height (m)², or in imperial units: 703 × weight (lb) ÷ height (in)².
- Is BMI accurate for athletes?
- BMI is less accurate for people with high muscle mass, such as athletes and bodybuilders. Muscle is denser than fat, so a muscular person may have a high BMI without excess body fat. For athletes, body composition measurements such as skinfold callipers, DEXA scans, or bioelectrical impedance are more informative than BMI alone.
- Can BMI be used during pregnancy?
- BMI is not an appropriate measure during pregnancy. Pregnant individuals are expected to gain weight as part of a healthy pregnancy. Healthcare providers use pre-pregnancy BMI as a baseline to guide recommended gestational weight gain ranges, which vary by starting BMI category.
- Does BMI apply to children?
- Standard adult BMI categories do not apply to children and teenagers. For individuals aged 2–19, the CDC uses BMI-for-age percentile charts that account for age and sex. A child's BMI is interpreted relative to peers of the same age and sex, not against fixed adult cutoffs.
- What are the limitations of BMI?
- BMI is a simple screening tool, not a diagnostic measure. Its limitations include: it does not distinguish between fat and muscle mass; it may overestimate risk in muscular individuals; it may underestimate risk in older adults who have lost muscle; it does not account for fat distribution (visceral vs subcutaneous fat); and its accuracy varies across ethnic groups. A BMI outside the normal range should prompt further evaluation by a healthcare professional.
- What is a healthy BMI for adults?
- According to the CDC and NIH, a BMI between 18.5 and 24.9 is considered normal weight for adults. However, 'healthy' depends on many individual factors. Some research suggests optimal health may be associated with BMI values in the 22–23 range, but individual variation is significant. Always consult a healthcare provider for personalised guidance.
Source & Methodology
- Tier 1 — Government / Official
- CDC Adult BMI Calculator
Tier-1 U.S. government source. CDC defines BMI categories for adults: underweight (<18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obesity (≥30). CDC also natively defines obesity sub-classes Class 1 (30.0–34.9), Class 2 (35.0–39.9), Class 3/Severe Obesity (≥40). - Tier 1 — Government / Official
- CDC: About Body Mass Index (BMI)
Tier-1 U.S. government source. CDC documents the BMI formula for adults: metric BMI = weight_kg / (height_m)², and imperial equivalent BMI = 703 × weight_lb / (height_in)². CDC characterizes BMI as a screening tool, not a diagnostic measure.