Are you wanting to say "I am 1 to 14 years old?" or "I'm ___ years old?"

as Korean age and European/American age are not the same, it's better to say when you were born. like this - 저는 99년 생이에요 = I was born in 99. literally, 'I am 14 years old' would be 1) 나는 14(열네) 살이야 - when you are talking to a younger or same-age person in a non-formal situation; 2) 저는 14(열네) 살이에요 - when you are supposed to show respect to your addressee. "열네 살" is "14 years". "나" and "저" are neutral and humble "I" (는 is topic ending). "이야" and "이에요" are informal and polite "am".