What should my bmi be at the age of 13 with a height and weight 6 stone 3lbs. is 14 i am wondering how underweight this is?

At 13 years old, with a height and weight of 6 stone 3 lbs (or 39 kg), your BMI (Body Mass Index) would be approximately 16.1.

For your age and gender, a healthy BMI range is between 14.5 and 19.9. Therefore, your BMI of 16.1 falls within the normal range.

However, it's important to note that BMI is just one indicator of overall health and well-being. Other factors such as body composition (muscle mass vs. fat mass), physical activity level, and diet also play a significant role in determining overall health.

If you have any concerns about your weight or overall health, it's always a good idea to consult with a healthcare professional for personalized advice and guidance.