BMI Calculator
Enter your height and weight to calculate your Body Mass Index (BMI). You can use either metric or imperial units.
What is BMI and why does it matter?
BMI stands for Body Mass Index. It is a screening tool that compares your weight to your height to estimate whether your body weight falls in a range that is generally considered underweight, healthy, overweight, or obese for adults.
A height weight BMI calculator gives you a quick number that can help you understand trends in your health. It is commonly used in clinics, fitness programs, and personal health tracking because it is simple, fast, and easy to repeat over time.
How to use this height weight BMI calculator
Step-by-step
- Select your unit system: metric (cm, kg) or imperial (ft, in, lb).
- Enter your height and weight values.
- Click Calculate BMI.
- Review your BMI score, category, and healthy weight range estimate.
For the most useful results, enter accurate measurements and recalculate occasionally to track progress.
BMI formula explained
Metric formula
BMI = weight (kg) / [height (m)]²
Example: If someone is 70 kg and 1.75 m tall, BMI = 70 / (1.75 × 1.75) = 22.9.
Imperial formula
BMI = 703 × weight (lb) / [height (in)]²
Example: If someone is 165 lb and 69 inches tall, BMI = 703 × 165 / (69 × 69) = 24.4.
BMI categories for adults
- Below 18.5: Underweight
- 18.5 to 24.9: Healthy weight
- 25.0 to 29.9: Overweight
- 30.0 and above: Obesity
These categories are population-level guidelines. Your personal health status may differ depending on muscle mass, age, ethnicity, medications, and existing conditions.
Healthy weight range based on your height
A useful feature of this BMI tool is the healthy weight range estimate. This is calculated from BMI values between 18.5 and 24.9 at your current height. It can be a practical target zone if you are planning weight loss or weight gain.
Remember: a healthy lifestyle is not only about the scale. Sleep, stress, nutrition quality, activity level, and mental well-being matter just as much.
Limitations of BMI
What BMI does well
- Quick screening tool for large groups
- Simple way to monitor change over time
- Easy to calculate from basic measurements
What BMI does not measure directly
- Body fat percentage
- Fat distribution (such as abdominal fat)
- Fitness level, strength, or metabolic health
Athletes with high muscle mass can have a high BMI but low body fat. Older adults can have a “normal” BMI while still having low muscle and higher health risks. Use BMI together with waist measurement, blood pressure, lab results, and medical guidance.
Practical tips to improve your BMI safely
- Aim for gradual change (about 0.25 to 0.75 kg per week for fat loss).
- Prioritize whole foods: lean proteins, fruits, vegetables, legumes, and whole grains.
- Strength train 2 to 4 times per week to preserve or build muscle mass.
- Include regular walking or cardio for heart health.
- Sleep 7 to 9 hours and manage stress to support recovery and appetite control.
- Track progress monthly, not just daily.
Frequently asked questions
Is BMI accurate for everyone?
Not perfectly. BMI is best used as a screening indicator, not a diagnosis.
Should children use this calculator?
Standard adult BMI categories are not used for children the same way. Children and teens should use age- and sex-specific BMI percentile charts.
How often should I check BMI?
Monthly or every few weeks is usually enough for trend tracking.
Final thoughts
A height weight BMI calculator is a great starting point for understanding your current weight status. Use the number as feedback, not judgment. If your goal is to improve health, combine BMI with sustainable habits and, when needed, advice from a qualified healthcare professional.