Tukuk-OS📱 Screen & PPI
ℹ️ What this tool does & how it works
A diagonal flatters big screens twice: area grows with the square of the diagonal, and a "13-inch" laptop is really about 28.7 × 18 cm of glass at 16:10. This page takes diagonal + pixel resolution (which fully determine the aspect ratio) and returns true width, height, and PPI = √(w²+h²)/diagonal for two devices at once — then compares them the way your eye actually experiences it: dots per inch and square inches.
Why diagonals lie about size
Two screens with the same diagonal can differ by 30% in area if their aspect ratios differ — a 16:10 panel and a 16:9 panel of the same diagonal are not the same purchase, because area is w × h and the diagonal only fixes the hypotenuse. The square-of-diagonal rule hurts marketing the other way too: going from a 6.1" to a 6.5" phone is a 13% area gain, not 7%, and that is the number your thumb feels. PPI has a similar trap: it measures dots, not legibility — at a metre away, 110 ppi looks fine, which is why desktop monitors got big before they got dense. The honest comparison is all three lines on this page together.