I had the same problem with Windows 8.1 and Paint. Here's how I solved it..
Open Paint (make sure there is no image in the work area) - Click File - click Properties - select INCHES for display - click OK
Now your Paint screen should display INCHES at the bottom center
Now use the window adjustment widget at the lower right corner of the work area window and adjust the window so the INCHES displayed at the bottom of your screen reads a minimum of 8.50 x 11.0 (Letter Size) - you can make it a bit larger (9.0 x 12.5 works), but too much larger will push you into using two sheets of copy paper for one image.. we're trying to remedy that problem. You'll have to play around with those numbers to fine tune your printed results.
That's it, pretty much. Except to make sure in Page Set-up your..
Paper Size = Letter
Page Set-up = Portrait
Horizontal & Vertical Centering are both selected
Left & Right Margins = 0 (zero) - - this will only reduce them to about .25 or so.. unless you have edge-to-edge printing capabilities in your printer, this is as low as you can set them for Letter type
Scaling = Fit to 1 by 1 Pages.
The Page Set-up must be reset all over again to match the above settings each time you close and reopen Paint, but the Properties' settings should remain unchanged.
Now, as long as you don't change the page size TOO much..whatever you print from Paint should fill one sheet of copy paper to within .25 inches of the sides and be just about right. To squeeze a bit more into that one sheet of copy paper, you can use the Page Set-up window to also adjust the Top & Bottom Margins to .25 inches - like the Left & Right Margins.
I believe this is about as much of the copy paper sheet as can be filled unless your copier has edge-to-edge print capability.