Renders PDF pages at their real physical size so you can measure drawings on screen with an actual ruler — plus on-screen machinist tools (distance, angle, radius, virtual scale).
First time? Tap Calibrate and match the on-screen bar to a real ruler or bank card. PDFs you open are kept on this device and reopen automatically — fully offline.
Hold a real ruler (or a bank card) flat against the screen and adjust until the target matches exactly. You only do this once per device.
PDFs stored on this device. They work fully offline and reopen at your last page.
True scale: calibrate once (Calibrate → match the bar to a real ruler or bank card). After that, 1″ on the drawing = 1″ on the glass in 1:1 mode — hold a real scale right against the screen.
Measuring tools (readouts in inches, thou, and mm):
Press the drawing and a magnifier bubble appears — drag to aim exactly, lift your finger to place the point. Two fingers pans the page while a tool is active.
↔ Distance — two points.
∠ Angle — one end, then the corner, then the other end.
◯ Circle — three points anywhere on a circle or arc; you get radius and diameter.
Undo removes the last point or measurement; Clear wipes them all.
📏 Ruler: one finger moves it; two fingers twist it like a real ruler (snaps at 45°). The round ⟳ handle also spins it — a quick tap on it steps 45°. The 16ths / .001″ button switches its inch edge between fractions and decimal — in 2:1 view the decimal edge shows true 10-thou ticks.
Drawing scale: if the sheet is marked e.g. SCALE 1:2, set it here and every readout converts to real part size. Angles never change.
Offline: every PDF you open is stored on this device and reopens by itself at your last page — no internet needed. In Chrome, use menu → Add to Home screen to install it like an app.