BMI Calculator
Enter your measurements below to calculate your Body Mass Index (BMI), category, and healthy weight range.
What is BMI and why does measurement accuracy matter?
BMI stands for Body Mass Index. It is a screening value based on your weight and height, and it helps estimate whether your body weight is in a healthy range for your height. A good BMI calculator with measurements is useful because even small input errors can change your result and category.
BMI does not directly measure body fat, but it is widely used in public health and clinical settings as a quick, low-cost indicator. By entering correct measurements in either metric or imperial units, you can get a more reliable baseline to guide nutrition, activity, and lifestyle decisions.
Measurements you need for this calculator
- Metric mode: weight in kilograms (kg) and height in centimeters (cm).
- Imperial mode: weight in pounds (lb), height in feet (ft), and inches (in).
How to measure height correctly
Stand against a wall without shoes, with your heels, hips, and upper back touching the wall when possible. Keep your head level and look straight ahead. Use a flat object (like a book) to mark the top of your head and measure from floor to mark.
How to measure weight correctly
Use a digital scale on a hard, flat surface. Weigh yourself at roughly the same time each day, ideally in the morning before eating, and with similar clothing. Consistency improves trend tracking.
BMI categories (adults)
- Below 18.5: Underweight
- 18.5 to 24.9: Normal weight
- 25.0 to 29.9: Overweight
- 30.0 and above: Obesity
Example calculations
Metric example
If someone weighs 70 kg and is 175 cm tall, BMI = 70 / (1.75 × 1.75) = 22.9. That falls in the normal weight category.
Imperial example
If someone weighs 180 lb and is 5 ft 10 in (70 inches), BMI = (180 / (70 × 70)) × 703 = 25.8. That falls in the overweight category.
Important limitations of BMI
BMI is a helpful screening tool, but it has limits. It may overestimate body fat in highly muscular people and underestimate risk in people with low muscle mass. It also does not show fat distribution.
For a clearer health picture, pair BMI with:
- Waist circumference
- Blood pressure and lab markers
- Physical activity level
- Diet quality and sleep habits
- Medical history and professional guidance
How to use your BMI result wisely
Use BMI as a starting point, not a final diagnosis. If your value is outside the normal range, focus on sustainable habits: balanced meals, strength and cardio training, hydration, sleep, and regular checkups. Small changes maintained over time are more effective than short-term extremes.
If you have a medical condition, are pregnant, are an athlete, or are calculating BMI for children/teens, consult a healthcare professional for interpretation specific to your situation.