Find the physical print size of an image at a given DPI.
10 × 6.67 inches at 300 DPI
At 300 DPI, 3000×2000 pixels prints at 10×6.67 inches. Print quality needs about 300 DPI; below 150 the print looks soft. Lower DPI means a bigger but coarser print.
What this cannot tell you
Take this with you
Pixels to Print Size Calculator on RunTheTests — free browser-based printer tools, no sign-up.