I'm a 16 yr old girl and i'm 5'1 and i weigh 99.4. is that underweight?

A bit: A general rule of thumb is that a good weight at 5 ft is 100 pounds and add five pounds for every inch of height. Another way to look at your weight is to look at your BMI and see if it is in the normal range. Your BMI is 18.7, normal is 18-24 so you are at the very low end of the normal range. A good indicator of your weight health is the presence of normal menstrual periods. Undernutrition will interfere with normal menstruation and when it gets to that point it will also lower your resting metabolism.

BMI: Your body mass is calculated at around 18, which is classified as normal to underweight. BMI should be interpreted on a patient to patient basis as it does not account for attributes such as muscle and body habitus. If you are feeling and looking healthy then you are at a healthy weight! :)

A bit: A general rule of thumb is that a good weight at 5 ft is 100 pounds and add five pounds for every inch of height. Another way to look at your weight is to look at your BMI and see if it is in the normal range. Your BMI is 18.7, normal is 18-24 so you are at the very low end of the normal range. A good indicator of your weight health is the presence of normal menstrual periods. Undernutrition will interfere with normal menstruation and when it gets to that point it will also lower your resting metabolism.