1. What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = kg/m² where kg is a person's weight in kilograms and m² is their height in meters squared. BMI screens for weight categories that may lead to health problems.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

Where:

• \( weight \) — Body weight in kilograms (kg)
• \( height \) — Height in meters (m)

Explanation: BMI provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

3. Importance of BMI Calculation

Details: BMI is a useful screening tool to identify potential weight problems in adults. However, it should not be used as a diagnostic tool. For example, a person may have a high BMI but not have excess body fat.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For most adults, an ideal BMI is in the 18.5 to 24.9 range. All values must be valid (weight > 0, height > 0).

5. Frequently Asked Questions (FAQ)

Q1: What are the NHS BMI categories?
A: Underweight (below 18.5), Healthy weight (18.5-24.9), Overweight (25-29.9), Obese (30 and above).

Q2: Is BMI accurate for everyone?
A: BMI may not be accurate for athletes (who may have high muscle mass), pregnant women, the elderly, or children.

Q3: How often should I check my BMI?
A: For most adults, checking every few months is sufficient unless you're actively trying to lose or gain weight.

Q4: Should children use this calculator?
A: No, children and teens need age- and sex-specific BMI calculations as their bodies change with growth.

Q5: What's a healthy BMI for older adults?
A: Some research suggests 23-27 may be healthier for people over 65 than the standard 18.5-24.9 range.