what kind of GPA do you have to have for art school?

Your GPA is relevant for getting into any college and university, but another incredibly important thing for applying to art schools is your portfolio.

I don't know what grade level you are at in school right now, but regardless of your age, draw, paint, take photos, make sculptures, sew, crochet, do whatever it is that you love to do and keep improving at it. Also document your work. Take good, well-lit photos of your work, scan your sketches, save those files, maybe even start a Tumblr where all you do is post your art works as a mini online portfolio. You will most likely have to showcase some work as part of the admissions process or to get some art scholarships. It's good to start now and practice having a good 8-15 pieces of art work you are really proud of and feel like they are a good example of your style.

Start thinking about some of the important questions that you would be asked in admissions and in class critiques at art school: Why do you make art? What is your perspective of the world that you share with your art? Are you trying to communicate specific thoughts? Do you have a specific message? Do you just like to do it because it feels good?

Back to what schools you should be looking for... Any school with an art program. If you already know what media (painting, illustration, printmaking, sculpture, photography, et cetera) you are interested in, start looking at programs that are strong in your interest area. If you don't know what you want to do just yet, that's fine. Most schools have a general fine art degree or don't have students declare a concentration until sophomore year.

Most importantly, you don't have to go to a famous art school to become an artist. The art world is complex and you probably won't be able to make a living exclusively off your art when you first graduate, so there is no need to go into crazy debt by going to a private art college or an out of state school. But that doesn't mean you should not apply to those schools either! Research local art schools, research your dream schools, and find out about all your financial aid options. Find out what programs are interesting for your, learn what the academic requirements of the school are. Work to bring your grades up as high as you can and keep making art! If your GPA is not going to get you admitted, consider starting at a community college for a year, take your English, maths, and other general requirements and study hard, get a good semester or two worth of grades and apply as a transfer student to the art program you want to get in to. Work with your guidance/career/college admissions counselor at school, they are there for a reason. Also, don't feel shy about emailing or calling the schools you are interested in. You can have your questions answered easily and you have the opportunity to schedule campus visits and see what the school is like.

Besides researching your school options, compete in high school art scholarship competitions. You can have the opportunity to win a little tuition money and get exposure. Check out if there is a Portfolio Day event near you (Visit http://www.portfolioday.net/ to see more) and use that as an opportunity to meet faculty at different art schools, ask questions, and learn about different art programs, while having the opportunity to have professional teaching artists give you feedback on your work.

And think about how you feel about sharing your work with other people. Art school involves putting you and your work on display and receiving constructive criticism about your ideas, the execution of you work, and more. If you are sensitive about this, art school might not be for you, but if you are willing to be brave and expose yourself in critique, you will learn so much from other art students and your art teachers. This is the best part of art school. Being immersed in art and surrounded by other people who do art. It will be the place that you grow very quickly and discover yourself. It will be hard work, but worth it! I know because I did it.

And I wish you luck! Practice, practice, practice, and study!

Do you plan to attend an art school that is part of a larger university or will you attend a private art school? Look at the schools you are interested in, and research their entrance requirements. Many applications to four year programs are due in the fall of your senior year. Are you ready to apply? What do you need to do to get ready? Map it out. Your portfolio is important, but if you are also applying for scholarships, your written statements should be flawless and coherent. Volunteer work also strengthens your scholarship applications. Get help with all of it.

As an artist you will need to write about your work, so this requires a good command of the English language. Many contemporary artists are interested in bringing other fields of study into their work, such as politics, sociology, gender studies, and medicine. Critical thinking is a skill that will serve you well no matter what direction you plan to take.
My point is, being an artist is no excuse to ignore your other studies. Other fields of study will ultimately enrich your work.
My undergraduate work was at an art school within a university (Rutgers, MGSA) and I was required to write a thesis in addition to my BFA exhibition. The same was true for my MFA.
As the previous writer mentioned, basic business courses will also serve you well. Good luck!