BMI calculator
Body mass index compares weight with height. It is a screening number for adults, not a measure of body fat.
Your details
Result
Enter your height and weight to see your BMI.
How it is calculated
BMI is weight in kilograms divided by the square of height in meters. Imperial inputs are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm) before the division.
BMI = weight (kg) / height (m)²The result is rounded to one decimal and placed in the CDC adult categories. The category follows the one-decimal value, as in CDC’s example table. At 5 ft 9 in, 125 lb (BMI 18.46, shown as 18.5) is healthy weight and 169 lb (24.96, shown as 25.0) is overweight. Pendum Body applies the same cutoffs to the unrounded BMI, so for a BMI less than 0.05 below 18.5, 25 or 30 the app names the category below the one shown here.
CDC adult BMI categories
| Category | BMI |
|---|---|
| Underweight | < 18.5 |
| Healthy weight | 18.5–24.9 |
| Overweight | 25.0–29.9 |
| Obesity | ≥ 30.0 |
For adults aged 20 and over, on the one-decimal BMI. Each edge belongs to the category above it.
The healthy-weight range for your height runs from the lightest to the heaviest weight, to 0.1 kg or lb, whose BMI shows as 18.5 to 24.9: 125.0 to 168.9 lb at 5 ft 9 in. Outside it, the change to reach it runs to the nearer end of the range and is rounded up to the next 0.1, so that it is enough.
BMI does not separate muscle from fat. A muscular person can read as overweight, and an older adult with little muscle can read as healthy. Body-fat percentage and FFMI describe composition better.
For adults aged 20 and over. Children and teens use age- and sex-specific percentiles instead. BMI is a screening tool, not a diagnosis.
Sources
Method and sources checked on by Svindland Software LLC.
Common questions
How is BMI calculated?
Weight in kilograms divided by the square of height in meters. Imperial inputs are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm) before the division, and the result is rounded to one decimal.
Which BMI counts as a healthy weight?
The CDC adult categories: underweight below 18.5, healthy weight from 18.5 to 24.9, overweight from 25.0 to 29.9 and obesity from 30.0. The category follows the one-decimal value, as in the CDC’s example table.
Does BMI measure body fat?
No. BMI compares weight with height and does not separate muscle from fat. A muscular person can read as overweight, and an older adult with little muscle can read as healthy. Body-fat percentage and FFMI describe composition better.
Does the BMI calculator work for children?
No. It is for adults aged 20 and over. Children and teens use age- and sex-specific percentiles instead, and BMI is a screening tool, not a diagnosis.
Does Pendum Body give the same BMI?
Not always. Pendum Body computes BMI from your trend weight, not one reading, and applies the same CDC cutoffs to the unrounded value, so for a BMI less than 0.05 below 18.5, 25 or 30 the app names the category below the one shown here.
Pendum Body tracks it over time
One-time purchase, $9.99 once. No account.
Pendum Body puts BMI beside body fat and FFMI on one dashboard, each with its adult reference label, and charts your trend weight above them.
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