Online PPI calculator, online screen pixel density query, can calculate the number of pixels per inch in the screen, also known as pixel density unit, the higher the PPI value, the clearer the picture.
Common screen PPI value reference:
Reference screen Size Resolution PPI
Amazon Fire HD 7 7" 1280*800 216
Amazon Fire HD 8 8" 1280*800 189
Mi Notebook air 13.3" 1920*1080 165.63
HTC One 4.7" 1920*1080 468
HUAWEI P40 Pro+ 6.58" 2640*1200 441
Mi 10 6.67" 2340×1080 386
Apple iPhone11 6.1 1792×828 326