Free Ruler2.0.19

Place horizontal and vertical rulers over the macOS desktop to measure on-screen distances. Free Ruler switches among pixels, millimeters, and inches when you press U, which helps with checking interface layouts, artwork, documents, and other visual dimensions.

The rulers can float above other applications, with F toggling that behavior so measurements stay visible while another window is active. Drag the end of either ruler to resize it, and press G to switch between moving the rulers independently and moving them as a group. The menu or keyboard can show, hide, and reopen the rulers, while O aligns them at the mouse location and Command-R resets their positions. Press S to show or hide the shadow behind the rulers, and choose from multiple available languages for the interface.

Free Ruler suits designers, developers, artists, and other Mac users who need quick screen measurements during interface work, image composition, document layout, or pixel-level inspection. It requires macOS 14 Sonoma or later and runs on both Intel and Apple Silicon Macs. The current version is 2.0.19, and the software is freeware and open source.