Screen Ruler for Pixels and On-Screen Distance

Measure a distance inside the browser with a draggable ruler. Pixel mode is for digital layout work; calibrated cm and inch modes are for physical objects held against the display.

Calibration is stored only in this browser.
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Drag across the ruler to measure a span.
⌨ Keyboard shortcuts

C cm · I inch · P px · R rotate · F fullscreen · G guides · X crosshair · A angle · D dark · 4 four edges

Calibrate1Ruler

Match a standard bank card width (85.60 mm) to the guide below.

85.60 mm

Pixel distance and physical distance are different

Pixel mode reports CSS-pixel distance in the current browser viewport. It is useful for interface spacing, screenshots and visual checks. Centimeter and inch modes convert screen distance into a physical unit and therefore need calibration.

Use horizontal or vertical orientation

The ruler can run across the page or switch to a narrow vertical rail. This is useful when you need to compare height instead of width, especially on long pages or tall mobile screens.

Use fullscreen for more working space

Fullscreen removes browser chrome from the immediate work area, while the popup option opens a ruler-only window. Neither mode changes the saved calibration by itself.

What can change a screen measurement?

Browser zoom, operating-system scaling and moving a window between displays can change the pixel-to-physical-size relationship. Pixel measurements remain digital, but physical units should be recalibrated after such changes.