There is a correlation between national ratings and international ratings (FIDE ratings), but there is nothing definite enough to say what your precise rating would be.
There are many previous forum threads that ask your question or similar ones. Why not look at some of them?
http://www.chess.com/forum/search?keyword=fide+rating
If my national rating is 1200, would my international rating be the same (1200)? What if my national rating is 2000?