This all depends on your purchase price and type of loan you are applying for. With an FHA loan, you only need to put down 3.5% and can write a portion of your closing costs in the loan if desired. So for example with FHA you would need the 3.5% down of the purchase price and about 3-4% for closing costs if you were going to pay them all on your own. You will also needs some funds for inspections, application fees for mortgages, etc.
With a Conventional Mortgage, you are looking at 10% (with PERFECT credit and a GOOD bank) or most likely, 20% for a down payment and then the same, 3-4% for closing costs and misc fees as stated above.
Hopefully this will give you a general idea to help you get on the right track. If you have any other questions, please do not hesitate to ask.
Best of luck!!