Screen Ruler measures distances on the glasses display in pixels and real-world units.
Measure: open the ruler and focus the measuring area (it glows). Use ◀ ▶ to move the active caliper, press Enter to switch between caliper A and B. The span shows live in px and your chosen unit.
Units: px→mm/cm/in conversion uses a PPI scale. The waveguide projects onto the world, so a pixel's real size depends on your view — open Calibrate and match the bar to a known object (credit card, coin, A4) for accurate units.
Tip: black areas are transparent on the display, so the ruler overlays whatever you are looking at.
Current scale: 96 PPI