Here is a blank playing card design template,
The Design area is: 2.24" x 3.24"
The Bleed area is: .24" x .24" (Should Match Whatever color you make the cards), I made it black because I am making a black card.
The full template area {red} is another .24" around to allow for cutting and such, it is 2.74" x 3.74" at 300 DPI which is what most print your own playing card online companies need for a template.
Enjoy: