How many exemptions should i claim if I prefer to have minimal withholding & instead write a check on 4/15?

I am single, no children. However, I do not want to give the government an interest-free loan of my money just to get back this gigantic refund at the end of the year. So, how many exceptions can I safely claim so I can maximize take-home pay and instead create a savings account so I could write a check to Uncle Sam at tax time? I was thinking 6. Thoughts?