Convert pixel dimensions to a print size at a chosen DPI, or work out the pixels and megapixels a print needs. Switch direction with the mode selector.
Print resolution is pixels per inch (PPI, often called DPI). 300 is a common photo-quality target, 150 is fine for large prints viewed from further away. This converts between pixel dimensions, print size and resolution.
Divide each pixel dimension by the DPI. At 300 DPI, a 6000 x 4000 pixel image prints at 20 x 13.3 inches (about 50.8 x 33.9 cm). Lower the DPI and the same file prints larger but with less detail.
300 PPI is the usual standard for prints held at reading distance. Large prints viewed from further away look fine at 150-200 PPI, and billboards far lower, because the eye cannot resolve the detail at distance.
Switch to print-size mode and enter the size and DPI: it multiplies the inch dimensions by the DPI to get the pixels, then the megapixels. An 8 x 10 inch print at 300 DPI needs about 7.2 megapixels.