BMI Calculator
A BMI calculator computes your Body Mass Index using height and weight to assess whether you are in a healthy weight range. BMI is a widely-used screening tool that estimates body fat based on measurements. Enter your height and weight and the tool instantly calculates your BMI and shows your category: underweight, normal, overweight, or obese. It also displays healthy weight ranges and explains what results mean. While BMI has limitations, it remains the standard starting point for weight assessment. BMI is calculated by dividing weight in kilograms by height in meters squared. For imperial, the tool automatically converts. The result is compared against WHO classifications: below 18.5 underweight, 18.5-24.9 normal, 25-29.9 overweight, 30+ obese. The calculator also shows ideal weight range based on healthy BMI for your height. All calculations happen instantly in your browser. Monitoring weight changes during diet and exercise. Initial health screening. Tracking fitness progress. Assessing weight-related health risks. Setting weight management goals. Evaluating growth patterns in children. Personal health awareness. Pre-employment health assessments. BMI is a screening tool, not diagnostic. Athletes may have high BMI without excess fat. Older adults may have normal BMI with low muscle mass. BMI does not account for fat distribution. Use alongside waist circumference for a more complete picture. Related tools: Age Calculator, Tip Calculator, Percentage Calculator, Discount / Sale Calculator, Loan / Mortgage Calculator. Browse all 123 free tools on the KitCraft home page.