BMI Calculator
Calculate your Body Mass Index (BMI) using metric or imperial measurements.
BMI Calculator
How to Use
Choose your preferred units
Toggle between metric or imperial depending on what you're comfortable with.
Pop in your measurements
Enter your exact height and your most recent weight.
Check the result
See where your BMI lands on the standard WHO health categories.
Why I Built This BMI Calculator
When I first started focusing on my fitness, I found myself constantly looking up BMI charts. Body Mass Index (BMI) isn't perfect — it's just your weight in kilograms divided by your height in meters squared — but it's a globally recognized starting point. According to the Centers for Disease Control and Prevention (CDC), it provides a reliable indicator of body fatness for most people, helping categorize weight into underweight, normal weight, overweight, and obesity. I wanted a calculator that didn't just spit out a number, but actually explained what the number means.
Real-World Examples & Use Cases
A Starting Point for Fitness
When I decided to get serious about my health, finding out my BMI was step one. It's the standard baseline used by the World Health Organization. While it doesn't tell the whole story, knowing if you're officially categorized as 'overweight' or 'normal' gives you a concrete reference point to start conversations with your doctor.
Setting Realistic Weight Goals
A lot of people pick an arbitrary target weight. Instead, you can use BMI to find the exact weight that puts you in the 'Normal' range (18.5 to 24.9). For example, if you're 5'9", finding out that 168 lbs puts you right at a healthy 24.8 BMI gives you a precise, scientifically backed goal to aim for.
Understanding Medical Screenings
Like it or not, insurance companies and healthcare providers still rely heavily on BMI. According to the NIH, a BMI over 30 is a clinical indicator that increases risks for type 2 diabetes and heart disease. Knowing your number beforehand means you won't be surprised during your annual physical.
How It Works
Here's the actual math happening under the hood: If you're using Metric: BMI = Weight in kg ÷ (Height in meters)² If you're using Imperial, there's a quirky multiplier because of how the units work: BMI = (Weight in lbs × 703) ÷ (Height in inches)² So, if you weigh 75 kg and you're 1.75 meters tall: BMI = 75 ÷ (1.75 × 1.75) = 24.5 (which is right in the normal range). Here are the official WHO boundaries: - Under 18.5: Underweight - 18.5 to 24.9: Normal weight - 25.0 to 29.9: Overweight - 30.0 and above: Obese
Frequently Asked Questions
Is BMI actually a good measure of health?▼
What's the 'Normal' range?▼
Does this work for kids?▼
Related Tools
Explore other tools in this category.
BMR & TDEE Calculator
Find your Basal Metabolic Rate and Total Daily Energy Expenditure.
Pregnancy Due Date Calculator
Estimate your baby's due date from your last period, conception date, or ultrasound.
Calorie Calculator
Calculate your daily calorie needs (BMR and TDEE) based on your activity level and weight goal.
Body Fat Calculator
Estimate your body fat percentage using the US Navy method or BMI-based formula.
Ideal Body Weight Calculator
Calculate your ideal body weight using four clinical formulas: Devine, Robinson, Miller, and Hamwi.
Water Intake Calculator
Calculate your recommended daily water intake based on body weight, activity level, and climate.