Watch the Introduction

Short walkthrough to get started with Ruler Overlay.

Getting Started

Have Ruler Overlay up and running in seconds.

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1. Installation

Download Ruler Overlay from the Store. Native distribution ensures seamless updates and a secure installation process.

Mac App Store

Microsoft Store

Linux (Coming Soon)

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2. Precision Calibration

For real-world accuracy (centimeters, inch), click Calibrate and use one of three methods: measure two known points on the ruler, click a quick-fill chip (credit card, A4 paper) to pre-fill the distance instantly, or enter your display's diagonal size (e.g. 27″) to let the app derive the exact PPI — ideal for external monitors with incorrect OS DPI. For standard digital work, pixel measurements (px) work perfectly out of the box.

Need a new baseline? In Linear Mode, hover near the delimiter/tick edge and drag horizontally (or use your mouse wheel) to shift the zero point instantly. Delimiters can be scrolled and will automatically snap to the ruler edges and the center when the green guide line is visible.

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3. Compact Mode

Enable Compact Mode for a slimmer, less distracting ruler with clearer ticks and a compact floating toolbar that reduces visual chrome while you work.

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4. Measurement Shortcuts

Open the measurement shortcut hint overlay to learn quick keys for starting/stopping measurements and nudging points. Arrow keys move points precisely; hold Shift for larger steps or Alt/Option for finer steps. Note: in px mode each arrow press is 1 pixel.

Core Features & Usage

Everything you need for precise digital measurements.

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Measurement Modes

Switch between powerful tools tailored for different layout needs.

Linear Mode: Standard absolute measurement. Drag the edges to quickly resize the ruler.
Linear Zero-Point Adjustment: Drag or scroll near the tick/delimiter area to move where measurement starts without resizing the ruler. Delimiters can be scrolled and will auto-snap to both ruler edges and the center when the green guide line is visible.
EKE Mode: An advanced Set Square mode for complex orthogonal alignments.
Grid Mode: A visual spacing guide for layout rhythm and proportional alignment.

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Precision Calibration

Three ways to calibrate for any monitor:

Two-point: Click two points on the ruler and enter the known distance — ruler computes the exact scale.
Known-object quick-fill: Click a chip (credit card, A4 paper, etc.) to pre-fill the distance instantly. No physical ruler needed.
Display diagonal: Enter your monitor's diagonal size (e.g. 27″ or 68.6 cm). Ruler derives accurate PPI from your screen resolution, fixing incorrect DPI on external monitors.

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360° Rotation

Grab the rotation handle to spin the ruler freely. It features buttery smooth mouse gestures, magnetic snapping around 15° increments, and fine rotation control between snap points for precise alignment.

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Two-Point Distance Measurement

Place two points anywhere on the ruler overlay to measure straight-line distance with your current unit (px, cm, inch). The tool works in both normal mode and Compact Mode, and a third click starts a new measurement instantly.

Keyboard control is built in: arrow keys nudge the active point — 1 px per press in px mode or 0.01 unit per press in other units (converted by your current scale); hold Shift for larger (×10) steps or Alt (Option / ⌥ on macOS) for finer (×0.1) steps.

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Instant Patch Updates

When a new patch is available, an update button appears in the toolbar — tap to download in the background, then tap again to restart and apply. No App Store wait, no manual reinstall (only applies to minor patches).

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Keyboard Shortcuts & Hints

Discover common actions via the built-in shortcut hint overlay (toggleable). Use shortcuts to start measurements, cancel (Esc), and precisely nudge measurement points with arrow keys and modifier steps.

Tailored to your aesthetic

Ruler isn't just functional; it's designed to look beautiful while you work without getting in the way.

Glassmorphic UI: Seamlessly blends with your workflow.
Always on Top: Keeps measurements visible above all your design tools.
Adjustable Appearance: Tweak opacity plus one combined color control for both ruler foreground and background colors.
Smart Persistence: Ruler remembers your exact size, angle, and linear zero-point offset on next launch, and recenters the window when you reopen it.

Changelog

Release notes & fixes.

Highlights

Improve performances.

Highlights

Added a single appearance control beside the opacity button that adjusts both ruler foreground and background colors.

Fixes

Stabilized EKE corner rotation.

Fixes

Ruler now opens centered on launch instead of restoring the previous window position from the last session.

Highlights

Improved macOS multi-display runtime scaling by blending active-display and primary-display PPI estimates when same-scale displays report sharply different physical sizes, reducing inaccurate external ruler sizing from bad metadata.

Fixes

Fixed multi-display calibration restoration so switching away and then back to a display now reapplies the saved calibration immediately in-session instead of only after restarting the app.
Fixed linear-mode fit resizing so Fit to Screen and Fit to Toolbar now preserve zero-point intent consistently: snapped zero points stay on left/center/right slots, and unsnapped zero points stay on their side of center while remaining in bounds when the ruler is fit.

Notes

v1.2.2 and v1.2.3 have been skipped.

Highlights

EKE measurement guides now show clearer x/y coordinate readouts from measurement points when the set square is at 90°.
Change from Reset Size to Fit to Toolbar for better clarity.

Improvements

In Linear Mode, when resizing the ruler while the zero point is snapped (to the left edge, center, or right edge), the delimiter stays locked to that snapped position for the entire resize gesture. Unsnapped zero points continue to follow proportional behavior.
Toolbar Fit to Screen and Fit to Toolbar buttons are now context-aware — each only appears when its action is meaningful, and both appear together when the ruler is at a custom intermediate size.
Fit to Toolbar now snaps the ruler to the exact minimum width needed to display the full toolbar, eliminating wasted space.
Safety confirmations: Added confirmation dialogs for Reset Scale (calibration reset) and closing while a calibration or measurement is active.
In Linear Mode, the zero delimiter and zero label now switch to a highlight color while dragging, making the zero point much easier to track.
Removed the Reset Rotation toolbar button — rotation now resets automatically when switching modes.

Fixes

Reduced intermittent delay when dragging the left resize handle in Linear Mode.
In EKE mode, Fit to Screen now applies extra safety padding to avoid clipping near screen edges.
EKE grid lines now anchor to the pivot zero point so the grid stays aligned with the ruler origin.
Fit to Screen now centers using visible screen bounds (including display offsets), so the ruler appears at the true screen center.
Linear ruler labels no longer show minus signs on the left side of zero, reducing visual clutter and keeping delimiter labels consistent while dragging the zero point.
Fixed Windows app exit behavior so toolbar Close and update Restart actions now close the desktop window reliably.

Highlights

Simpler, adaptive toolbar — actions are easier to find and the toolbar adapts to small widths.
Clearer measurement overlays and labels for faster, less error-prone readings.
Three calibration methods: classic two-point, known-object quick-fill chips (credit card, A4), and display diagonal entry for reliable inch/cm on any external monitor.
Better multi‑display handling and improved unit accuracy across monitors.
Easier EKE (set‑square) measurements with improved layout and alignment guides.
Finer opacity control (1% steps) so you can tune visibility precisely while working.
More reliable zero‑point and snapping behavior in linear mode.
The calibrated physical unit is now labeled cm (Centimeters) throughout the app, replacing the previous u label for clarity.

Improvements

Cleaner visuals and more readable labels across the app.
Smoother button and hover interactions for faster workflows.
Opacity adjustments now behave consistently across UI components.
Compact mode and rotation feel smoother and more predictable.

Fixes

Fixed toolbar sizing to avoid hidden buttons on narrow rulers.
Fixed rotation initialization issues that could cause misalignment.
Multiple layout fixes to prevent clipping and improve text visibility.
Updated privacy wording for clarity.

Highlights

Compact Mode: slimmer, low‑chrome ruler with clearer ticks and a compact floating toolbar.
Two‑Point Distance Measurement: place two points to measure straight‑line distance; supports keyboard nudging.
Measurement shortcut hint overlay and keyboard shortcut handling, with a visibility toggle.
Vertical guide line support in EKE mode for improved orthogonal alignment.
Adaptive grid spacing and aligned grid lines to the ruler zero point for better accuracy across units and scales.
Opacity control: toolbar popover slider (auto-dismisses when clicking outside) and keyboard shortcuts (`[` / `]`) to quickly adjust ruler transparency; persisted across restarts.
Extended unit button visibility in EKE mode and a refreshed compact mode toggle icon.

Improvements

Zero‑point snapping: refined snapping behavior and sticky magnet handling to reduce accidental snaps.
Rotation & EKE: improved anchor logic, angle‑snapping tweaks, rotation persistence, and more stable pointer/gesture behavior.
Rendering & layout: updated ruler dimensions, grid drawing, padding/margins, and text positioning for better readability and usability.

Fixes

Keyboard shortcuts: more reliable handling and consistent behavior across modes.
Selected angle initialization and reset logic.
Various rendering and test fixes (grid alpha, sticky snap target handling).