How to Use BMI Calculator

1

Select Unit System

Choose Metric (kg, cm) or Imperial (lbs, feet/inches) based on your preference and location.

2

Enter Height

Input your height accurately. For metric: centimeters. For imperial: feet and inches separately.

3

Enter Weight

Input current body weight. Use morning weight after bathroom for most consistent results.

4

Review Your Category

See your BMI number and category (Underweight, Normal, Overweight, Obese) instantly.

📊 BMI Categories (WHO Standards)
  • Under 18.5: Underweight
  • 18.5 - 24.9: Normal weight
  • 25.0 - 29.9: Overweight
  • 30.0 and above: Obese

Frequently Asked Questions

Is BMI accurate for everyone?
BMI is a screening tool, not diagnostic. It doesn't account for muscle mass, bone density, or fat distribution. Athletes may have high BMI but low body fat. Consult doctors for complete assessment.
What's the ideal BMI for my age?
BMI categories are same for adults 18-65. For elderly (65+), slightly higher BMI (23-27) may be protective. Children and teens use BMI percentiles based on age and gender.
How often should I check BMI?
Monthly is sufficient for most people. Daily fluctuations are normal - focus on trends over weeks/months, not day-to-day changes. Weight yourself same time daily for consistency.
Can I use BMI during pregnancy?
No! BMI is not accurate during pregnancy. Use pregnancy weight gain charts based on pre-pregnancy BMI. Consult your obstetrician for healthy weight targets.
What's better than BMI?
Waist-to-hip ratio, body fat percentage, and waist circumference are better health indicators. BMI is popular because it's simple to calculate without special equipment.

Related Tools

Percentage Calculator

Click to try this related tool.

EMI Calculator

Click to try this related tool.