This executable example uses the same formulas and rounding contract as the calculator: 2560 native pixels wide, 1440 high and a 27-inch visible diagonal.
Pixel diagonal: 2,937.209560 px
√(2560²+1440²) = √8,627,200. The calculator evaluates the integers directly and displays 2,937.209560 px rounded to six places.
Density: 108.785539 PPI
Divide 2,937.209560 by 27. Equivalent derived displays are 42.828952 px/cm and a 0.233487 mm ideal pixel pitch.
Panel rectangle: 23.532540×13.237053 in
The same geometry is approximately 59.772650×33.622116 cm, with reduced 16:9 ratio, 3,686,400 total pixels and 3.6864 MP.
What this number is useful for
PPI makes displays with different resolutions and physical sizes comparable on one density scale. It does not predict perceived sharpness by itself because viewing distance, eyesight, panel structure and software scaling also affect the experience. Keep those factors separate when comparing this result with another screen.