Print Sizes - photo labs

Gidday,
This has probably been asked mulitple times ( I did a search but couldn't find the answer I wanted/needed ).
When preparing images to print at a photo lab ( say 4" x 5" ) do I make my images this exact size? I have been told to make them twice the size and the lab will "shrink to fit" without cropping?
I would expect that the exact size is the answer, I was just wondering what people do. Is there a tutorial on this topic?
Cheers.
This has probably been asked mulitple times ( I did a search but couldn't find the answer I wanted/needed ).
When preparing images to print at a photo lab ( say 4" x 5" ) do I make my images this exact size? I have been told to make them twice the size and the lab will "shrink to fit" without cropping?
I would expect that the exact size is the answer, I was just wondering what people do. Is there a tutorial on this topic?
Cheers.