Ruler by Xalpha Lab is a great example of a good ruler app. The app is entirely free with no ads or in-app purchases. It also comes with both imperial and metric units for your convenience.

It has one design oversight in that the imperial ruler along one edge is scaled in 1/8″ increments! I have never seen a PCB laid out on a 0.125″ grid and I don’t know of any PCB designers who, even in ...

A standard ruler is a straight-edge marked at equal distances of a unit length (a mark for every inch, for example). This may seem like a surprising object to need to define, but there’s a ...