BMI Calculator and Body Mass Index Guide
Use this BMI calculator to estimate your body mass index with metric or imperial units. It helps you calculate BMI quickly, compare the result with standard adult BMI categories, and understand the basic BMI formula without extra steps. If you want to know how to calculate BMI, check BMI calculator UK or NHS BMI calculator wording, or compare adult BMI guidance with CDC references, this page brings the core formula, examples, and interpretation together in one place.
Result
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Category
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Adult healthy range
18.5 to 24.9
Method used
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Quick Answer: BMI compares your weight with your height. To calculate BMI, divide weight in kilograms by height in meters squared, or use pounds and inches with the factor 703. For most adults, a BMI from 18.5 to 24.9 is considered a healthy range, while children and teens should use BMI-for-age percentiles instead of adult cutoffs.
How to Calculate BMI Calculator and Body Mass Index Guide
- Enter weight and height - Use kilograms and centimeters for the metric BMI formula, or pounds with feet and inches for the imperial formula.
- Apply the BMI formula - Divide weight by squared height. If you use pounds and inches, multiply the result by 703 to get the same BMI value.
- Compare the result with adult BMI ranges - A BMI below 18.5 is underweight, 18.5 to 24.9 is healthy weight, 25 to 29.9 is overweight, and 30 or more falls in the obesity range for adults.
BMI Calculator and Body Mass Index Guide Formula
BMI = weight (kg) / height (m)^2 | BMI = [weight (lb) / height (in)^2] x 703
| Variable | Meaning | Unit |
|---|---|---|
| Weight | Body weight measured in kilograms or pounds | kg or lb |
| Height | Body height measured in meters, centimeters, feet, or inches | m, cm, ft, in |
| BMI | Body mass index used as a screening estimate for weight status | kg/m^2 |
Worked Examples
USA
Adult BMI calculator for women
- Weight: 150 lb
- Height: 5 ft 5 in
- Formula: (150 / 65^2) x 703
Result: 25.0 BMI
This adult BMI result sits at the edge of the overweight range. It can be a useful screening flag, but body composition and waist size still matter.
UK
NHS BMI calculator style example for men
- Weight: 82 kg
- Height: 178 cm
- Formula: 82 / 1.78^2
Result: 25.9 BMI
This BMI calculator UK example lands in the overweight category under standard adult ranges. A review of waist circumference and lifestyle habits would add more context.
EU
Adult BMI calculation for office worker
- Weight: 68 kg
- Height: 172 cm
- Formula: 68 / 1.72^2
Result: 23.0 BMI
This result falls inside the healthy adult BMI range and is often used as a general screening reference in EU clinical guidance.
GCC
Male BMI calculator screening example
- Weight: 94 kg
- Height: 180 cm
- Formula: 94 / 1.80^2
Result: 29.0 BMI
This BMI calculator male example is in the overweight range and close to obesity. It may support a broader review of activity, nutrition, and cardiometabolic risk.
How to Interpret Your BMI Result
| Range | Meaning | Action |
|---|---|---|
| Below 18.5 | Underweight | Review nutrition, unintended weight loss, and medical history with a clinician if the result is persistent. |
| 18.5 to 24.9 | Healthy Weight | Maintain current habits and track BMI alongside waist size, fitness, and blood pressure. |
| 25.0 to 29.9 | Overweight | Check waist circumference, activity levels, and diet quality to understand whether risk is increasing. |
| 30.0 and above | Obesity | Use BMI as a starting point for a fuller health review and discuss long-term risk reduction with a clinician. |
Frequently Asked Questions
To calculate BMI, divide your weight in kilograms by your height in meters squared. If you use pounds and inches, divide weight by height squared and multiply by 703. Both formulas give the same body mass index result when the measurements are entered correctly.
Yes. This page is designed as a general adult BMI calculator, so it works for routine body mass index checks with standard BMI ranges. The formula is the same across adults, but interpretation can still vary with age, body composition, and clinical context.
Yes. The NHS BMI calculator uses the same standard adult BMI formula, so the BMI calculator UK result here should match the same measurements. NHS guidance may add extra context such as waist size, ethnicity considerations, and child BMI guidance.
For adults, yes. CDC BMI calculator guidance uses the same adult BMI formula. The difference is that the CDC also provides special BMI-for-age percentile tools for children and teens, so child BMI calculator use should follow age- and sex-specific charts rather than adult cutoffs.
It can help you understand the formula, but adult BMI categories should not be used for children. Child BMI tools need age- and sex-specific percentiles, because healthy growth patterns change throughout childhood and adolescence.
Not always. BMI is a screening measure and does not separate muscle, bone, and fat mass. A very muscular person can have a higher BMI without having excess body fat, which is why waist circumference, training history, and body composition can matter.
For most adults, a BMI from 18.5 to 24.9 is considered a healthy range. Values below that range suggest underweight, while values above it move into overweight or obesity categories. BMI is useful for screening, but it is not a full diagnosis by itself.
If your weight is stable, checking BMI a few times per year is usually enough. If you are actively trying to lose weight, gain weight, or monitor a health plan, monthly checks can be reasonable as long as you interpret BMI with other measures.
Convert your height to total inches first, square that number, divide your weight in pounds by the squared height, and multiply by 703. This is the standard imperial BMI calculation used across many online BMI calculator tools.
Related Calculators
Disclaimer: This BMI calculator is a screening tool, not a diagnosis. It does not directly measure body fat, and child, teen, pregnancy, and athletic cases may need more specific assessment.
Sources
- World Health Organization - Body mass index classification
- CDC - About adult BMI
- NHS - Calculate your body mass index
Last reviewed: March 2026