BMI calculator, see if your weight fits your height
BMI (Body Mass Index) is a single number that tells you whether your weight matches your height. You get a value somewhere between the teens and the forties, and that number tells you whether a doctor would file you under "underweight", "healthy", or "overweight".
Type in weight and height: the calculator runs the math instantly. It also shows the healthy weight range for your height (what you'd need to weigh to land in the normal zone) and BMI Prime (your BMI divided by 25, handy for "how far am I above or below the line").
Important: BMI is a screening tool, not a diagnosis. It can't tell muscle from fat (a lean athlete can read "overweight"), and it doesn't account for age, sex, or ethnicity. Treat it as one signal among many: not a verdict.
How to use it
- Pick units: kg/cm (most of the world) or lb/ft+in (US, UK).
- Enter weight: best taken in the morning, before breakfast, after using the bathroom. That's when the number is most consistent.
- Enter height: measured without shoes, in cm or feet+inches. If you don't remember, check a recent doctor's record or measure against a wall.
- Optional, toggle "Asian population" if your background is South or East Asian. WHO recommends lower thresholds for this group (more on why in the FAQ below).
- Result appears immediately: BMI number (large, center), category badge (green = normal, yellow = overweight, orange/red = obesity), and a plain-English description of what it means.
- BMI bar: shows where you sit on the scale, with markers at 18.5, 25, 30, 35, 40. The needle marks your spot.
- Healthy weight range: actual pounds or kilograms you'd need to weigh at your height to fall inside the normal BMI band (18.5-24.9). Concrete numbers, not vague advice.
When this is useful
The most common reasons people type weight and height into a BMI calculator:
- Checking after a holiday or vacation: you feel heavier, the scale jumped 5-7 lb. Are you still in the normal zone, or did you cross into "overweight"?
- Tracking diet progress: you've been eating better for a few weeks and want to know when you'll cross from "overweight" back into "normal". The calculator tells you exactly how many pounds (or kg) you need to drop.
- Doctor's intake form asked for BMI: on a form, a referral, or a telehealth questionnaire. Punch in weight and height, get the number with the category, done.
- Weight vs body composition: you've been lifting, eating more protein, gaining muscle. Your weight is up. So is your BMI. Is BMI still meaningful for me, or am I one of those "overweight athletes"?
- Pre-checkup prep: annual physical coming up, the doctor will probably ask. Better to know the number in advance than fumble with a calculator in the office.
- Checking BMI for a partner, kid, parent: someone in the family wants to know but doesn't want to do the math. You enter their numbers, you read the result.
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