BMI Calculator
| Classification | BMI |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 - 24.9 |
| Overweight | 25.0 - 29.9 |
| Obesity class I | 30.0 - 34.9 |
| Obesity class II | 35.0 - 39.9 |
| Obesity class III | ≥ 40.0 |
What is BMI (Body Mass Index)?
Body Mass Index, or BMI, compares your weight with your height to offer a quick screening of whether your weight falls within a range that is generally associated with good health. Doctors and fitness professionals often use BMI as a first look at whether someone might be underweight, at a healthy weight, overweight, or obese.
This calculator instantly computes your BMI and shows the category you fall into. Enter your weight and height in the units you prefer—kilograms or pounds, centimeters or inches—and the script converts everything behind the scenes. The result displays both the numeric value and the matching weight classification so you can interpret the number at a glance.
Why Track BMI?
Keeping BMI within the recommended range can reduce the risk of heart disease, type 2 diabetes, and high blood pressure. Seeing your number provides a clear starting point for conversations with your doctor and helps you set realistic goals. Because BMI is easy to calculate regularly, you can watch how lifestyle changes shift the value over time.
Understanding the Categories
Your BMI score places you into one of several ranges. Being underweight may prompt you to add calories or evaluate medical issues. The normal weight range suggests your body size is broadly aligned with population averages. Overweight and obesity categories signal elevated health risks and often encourage adjustments to diet, exercise, and medical follow-up.
The calculator also highlights the healthy weight range for your specific height and can show the BMI associated with a goal weight. Visualizing how far you are from the target range makes it easier to plan gradual, sustainable changes.
Accuracy and Limitations
BMI is a helpful general indicator but it does not distinguish between muscle and fat. Athletes with substantial muscle may receive a higher BMI despite excellent health, while older adults with less lean mass may fall within the normal range even if body fat is elevated. Ethnicity, age, and body composition all influence how BMI should be interpreted.
Because of these nuances, BMI should be paired with other information such as waist circumference, body fat percentage, blood pressure, and lab work. Treat BMI as a screening tool that can prompt deeper assessment rather than a final verdict on your health.
Using the Calculator
- Enter your current weight and choose the appropriate unit.
- Provide your height and select centimeters or inches.
- Optionally add a target weight to compare the BMI you would reach.
- If you know your age, gender, and typical activity level, supply them to estimate basal metabolic rate (BMR) and total daily energy expenditure (TDEE).
- Press Calculate BMI to generate results and use the copy button to save the summary.
Beyond BMI
To build a fuller picture of wellness, consider combining BMI with waist circumference, waist-to-height ratio, or body fat measurements. These metrics reveal how fat is distributed and whether it concentrates around the abdomen, which is a stronger predictor of metabolic risk than BMI alone.
Frequently Asked Questions
Is BMI the same for everyone? The tool is intended for adults. Children and teenagers rely on age- and sex-specific growth charts, and athletes or pregnant individuals may need more specialized assessments.
Can BMI replace professional advice? No. Use it as a discussion starter with qualified health professionals who can interpret the number within the context of your medical history and overall lifestyle.
By pairing regular BMI checks with mindful eating, consistent activity, and professional guidance when needed, you can use this calculator as a practical companion on your journey toward long-term health.