In the United States the standard size for business cards is 3.5" x 2". If you need your cards with full bleed (which means the ink goes all the way to the end of the paper) you'll need to provide us with a file that has an excess of 1/8" all around. We also recommend that ALL important content should be kept inside a safe border of 1/8".
Take a look at the templates below for both vertical and horizontal. We are providing them in .jpg as a reference.