I like turbo tax and use it to figure out my taxes also but in the mean time. . .
go the the good old irs. On irs.gov, I think it's in the bottom right corner. . .it will have an exemption calculator. It's really easy. . .do the calculations and at the end it will give you a pretty accurate figure.
btw, we are a family of 7 and take 13 deductions and still end up with about $2000 back.
