Edge Ruler

Edge Ruler turns iPhone and iPad into a ruler that measures from the device corner. Hold the corner against an object, read length and width. No camera trick, no guessing: the app knows, for every device, the distance from the housing edge to the first pixel and draws the scale to the millimeter. Two corner rulers in opposite corners, two measuring lines with handles that lock when released, values in cm, inches with fractions or 寸. With Calibrate you place a bank card or coin on a real-size template and see at once whether everything lines up; bezel values can be adjusted in tenths of a millimeter. Five school worlds as outfits: grid paper and clear ruler like a German pencil case, yellow wooden ruler on wide-ruled paper like in the US, 田字格 with a tinted student ruler like in China, Seyès notebook with a “double décimètre” like in France, “cuadrícula” with a “regla” like in Spain. Paper, ruler, line color and unit combine freely. The basic ruler is free. Everything else can be tried for 14 days and then unlocked once: your region's outfit with second scale, rotating numbers, all four zero corners, movable zero, measurement table and inclinometer, or all five school worlds at once. Accurate to about 0.3 mm on calibrated models; not a certified measuring instrument. No data collected, no account, no internet.