Free BMI Calculator (Body Mass Index)
Check your weight category instantly. Metric & Imperial supported. Clean, mobile-friendly, and SEO-optimized.
BMI Calculator
Your BMI: —
Category: —
Tip: BMI is a general indicator. For athletes or very muscular individuals, consider body fat % too.
What is BMI?
Body Mass Index (BMI) is a simple ratio of weight to height used to classify underweight, healthy weight, overweight, and obesity in adults. It helps screen potential health risks, but it does not directly measure body fat.
BMI Formula
Metric: BMI = weight(kg) ÷ [height(m)]²
Imperial: BMI = 703 × weight(lb) ÷ [height(in)]²
BMI Categories
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity | ≥ 30.0 |
Limitations
- Does not differentiate between muscle and fat mass.
- Ranges may vary for athletes, older adults, and different populations.
- Use alongside waist measurements or body fat % for better insight.
FAQs
What is a healthy BMI?
For most adults, a healthy BMI is between 18.5 and 24.9. Aim to pair BMI with lifestyle factors like diet, sleep, and activity.
Is BMI accurate for athletes?
BMI may overestimate body fat in muscular individuals. Consider body fat % or waist-to-height ratio for additional context.
Can I use BMI for children?
Children use BMI percentiles adjusted for age and sex. Consult pediatric growth charts or a healthcare professional.
How can I improve my BMI?
Combine balanced nutrition, regular activity, and adequate sleep. Speak to a professional for personalized guidance.
Planning calories? Try our BMR & TDEE Calculator to estimate daily needs.