BMI Calculator
Calculate your Body Mass Index (BMI) using metric or imperial units.
How this calculator works
BMI = weight (kg) ÷ height (m)². It's a quick population-level screening tool, not a diagnosis — it doesn't distinguish muscle from fat, so athletes and very muscular people often score "overweight" despite low body fat.
What this result means
BMI sorts you into one of four bands: under 18.5 is classified underweight, 18.5–24.9 is the "healthy weight" range used in most public health guidelines, 25–29.9 is overweight, and 30+ is the obesity range. These thresholds come from population studies and are the same for men and women, which is part of why BMI is a screening tool rather than a diagnostic one — it doesn't account for frame size, muscle mass, age, or where on the body fat is carried, all of which affect actual health risk more precisely than a single number.
Where you fall on the scale
Run the calculator above to see where your BMI sits across the four standard categories.
Average and healthy BMI for women vs. men
The healthy BMI range — 18.5 to 24.9 — is the same threshold used for both men and women; there's no separate official "female" scale. Within that range, though, the numbers mean something slightly different by sex: women typically carry a higher percentage of body fat than men at the same BMI, so a woman and a man with an identical BMI can have meaningfully different actual body composition. A BMI around 21–23 sits comfortably mid-range as a commonly cited "average" healthy figure for adult women, while men's average is often reported slightly higher due to typically greater muscle mass at the same BMI. Neither figure is a target to chase — where you sit within the healthy band matters far less than trends over time and other health markers.
Common mistakes
- Treating BMI as a direct health verdict. It's a screening number, not a diagnosis — a muscular athlete and a sedentary person can share the same BMI with very different actual health profiles.
- Ignoring waist circumference. Where fat is carried (especially visceral fat around the abdomen) matters for health risk independently of overall BMI.
- Using adult BMI categories for children or teens. Pediatric BMI is assessed using age- and sex-specific percentiles, not the fixed adult thresholds used here.
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Frequently Asked Questions
What's a good or average BMI for a woman?
18.5–24.9 is the healthy range for women, same as for men — there's no separate official female scale. Within that band, roughly 21–23 is often cited as a typical "average" figure, but the range itself matters more than any single midpoint number.
Is a BMI of 23.7 good for a woman?
Yes — 23.7 falls within the 18.5–24.9 healthy weight range. It sits in the upper-middle of that band, comfortably clear of both the underweight and overweight thresholds.
What's a healthy weight range for men by height?
The same 18.5–24.9 BMI band applies, but because the formula is height-squared, the healthy weight in kg or lb varies a lot by height. Enter your height above to see your exact healthy weight range, or see the full breakdown by height.
Is BMI accurate for muscular or athletic people?
Not reliably. BMI can't distinguish muscle mass from fat mass, so athletes and bodybuilders often score "overweight" or "obese" despite low body fat. The Body Fat Calculator gives a more relevant picture for muscular builds.
What's considered a healthy BMI?
18.5–24.9 is classified as the healthy weight range in standard public health guidelines, used the same way for adult men and women. It's a population-level guideline, not an individual prescription.
Does BMI work the same way for children?
No. Children and teens are assessed using age- and sex-specific BMI percentiles rather than the fixed adult categories (underweight/healthy/overweight/obese) used on this page.
Why do metric and imperial give slightly different results?
They shouldn't in principle — both use the same underlying formula (weight divided by height squared), just with a conversion constant for imperial units. Small differences usually come from rounding the input measurements.