How do you adjust pcb layout to print the proper size?

I printed a pcb layout i got online, and the board is just slightly smaller than it should (hardware doesn't line up with the holes). Is there any way to fix this?

What operating system?
What printer?
What software?

Without that we are only guessing around.

OS is windows 8.1, printer is whatever i can find that uses toner, and software is gimp/eagle

Just realized the eagle pdf export auto sizes it.

I always exported to BMP, and then printed from MSPaint (being sure to turn off the fit to page functionality)