BMI Calculator
Calculate your Body Mass Index in metric (kg/cm) or imperial (lb/in) units. Enter your height and weight to see your BMI and which category it falls into — all in your browser, nothing uploaded.
- 🔒 100% private — no uploads
- 🆓 Free, no watermark
- 📱 Works on any device
How to calculate
- 1
Choose metric or imperial
Switch units with one tap; the fields update to kg/cm or lb/in.
- 2
Enter height and weight
Type your measurements. The BMI updates live as you type.
- 3
See your BMI and category
Your BMI and its category (underweight, normal, overweight, obese) appear instantly.
Why use BMI Calculator?
Metric & imperial
Works in kg/cm or lb/in — switch any time without re-entering.
Category included
Shows the standard WHO category alongside the number.
100% private
Your measurements never leave your device — useful for sensitive health data.
Any device
No install or account; works on phone or desktop.
What your BMI means
Body Mass Index divides your weight by your height squared to give a single number that estimates whether you’re in a healthy weight range: under 18.5 is underweight, 18.5–24.9 normal, 25–29.9 overweight and 30+ obese. It’s a quick screen, not a diagnosis — it doesn’t distinguish muscle from fat or account for frame, age or sex, so treat it as one rough indicator among many.
Limitations and better context
Athletes and very muscular people often land in the “overweight” category despite low body fat. Older adults and some ethnic groups have different healthy ranges. Waist circumference, body-fat percentage from calipers or DEXA, and how clothes fit are often more useful than BMI alone. Use the number as a conversation starter with a doctor, not a verdict.
Frequently asked questions
How is BMI calculated?
Metric: weight (kg) ÷ height (m)². Imperial: 703 × weight (lb) ÷ height (in)². This tool does the conversion for you.
Is BMI accurate?
It’s a useful general screen but has limits — it can over- or under-estimate body fat for very muscular or older people. Use it alongside other measures, not on its own.
Do my numbers get uploaded anywhere?
No. Every calculation runs entirely in your browser — your income, loan amount, balances and goals never leave your device. There’s no account and nothing is sent to a server.