If the image is 3000 pixels wide and no print size is specified, the image will print to 3000 dots wide. 1 pixel —> 1 dot.

If the printer's resolution is 300 dots per inch, then the resulting print will be:

3000 dots ÷ 300 dpi = 10” wide.

A 3000 X 2000 pixel image sent to a printer whose resolution is 300 dpi will result in a print that is 10" wide X 6.7" high. (2000 ÷ 300 = 6.7 )