BMI Calculator
Calculate your Body Mass Index instantly. Switch between metric and imperial units.
BMI is a screening tool, not a diagnostic measure. It does not account for muscle mass, bone density, or fat distribution. Consult a healthcare professional for a complete health assessment.
Free BMI Calculator
Zolkit's BMI calculator computes your Body Mass Index instantly from height and weight in either metric (cm/kg) or imperial (ft·in/lbs) units. Results include a color-coded category badge, a visual scale bar showing your position in the BMI spectrum, and a personalized healthy weight range calculated for your exact height. All calculations run locally in your browser — no data is transmitted.
Instant BMI Calculation
Enter your height and weight and see your BMI immediately. Results update as you type — no button to press.
Metric & Imperial
Switch between metric (cm/kg) and imperial (ft·in/lbs) with one tap. The calculator handles the unit conversion automatically.
Color-Coded Categories
Your BMI is displayed with a color-coded category badge and a visual bar showing where you fall on the BMI scale.
Healthy Weight Range
See the healthy weight range for your specific height — not just a generic number — so you know exactly where you stand.
Private by Design
All calculations happen locally in your browser. Your personal health data is never sent to any server.
Free, No Sign-Up
No account, no subscription. Just enter your numbers and get your result.
How to Calculate Your BMI
- 1
Select your preferred unit system using the toggle at the top. Metric uses centimeters and kilograms; Imperial uses feet, inches, and pounds.
- 2
Type your height and weight into the input fields. Your BMI appears instantly below the inputs.
- 3
Your BMI number is shown with a color-coded category (Underweight, Normal, Overweight, or Obese) and a horizontal scale. Your healthy weight range is also displayed.
Frequently Asked Questions
What is BMI?
Body Mass Index (BMI) is a number calculated from your height and weight: BMI = weight(kg) / height(m)². It is used as a general indicator of healthy weight ranges for adults.
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate for everyone?
BMI is a population-level screening tool and has well-known limitations. It does not distinguish between muscle and fat, so athletes may appear overweight. It also doesn't account for age, sex, or ethnicity differences in body composition.
How is BMI calculated in imperial units?
With imperial units, BMI = (weight in lbs × 703) / (height in inches)². The calculator converts your feet and inches to total inches automatically.
What is the healthy weight range shown in the results?
The healthy weight range is calculated by solving the BMI formula for weight at BMI 18.5 (lower bound) and 24.9 (upper bound) for your specific height. It gives you a personalized target range.