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Free Design Tool

Pixel Ruler — Measure Pixels Online

A free online screen ruler that measures exact pixel dimensions, picks colors, and verifies UI spacing. Designed for web designers, UI/UX developers, and digital artists who need pixel-perfect accuracy.

Crosshair
Snap
Grid
Checkerboard
Zoom: 100%
Cursor: 0px, 0px

Drop or paste an image. Click a ruler to add a guide (drag to move, right/⌘-click a ruler to remove). Hold Space or use the middle mouse to pan. Use Ctrl/Cmd + wheel to zoom. Click the image to pin and copy a color. Drag the selection handles to resize.

What Is a Pixel Ruler and When Do You Need One?

A pixel ruler measures the exact pixel dimensions of elements on your screen — buttons, images, spacing, icons, banners, anything you can see. While physical rulers measure in millimeters or inches, a pixel ruler speaks the language of screens. If you work in web design, app development, or UI/UX, you need to know how many pixels wide a sidebar is, whether that margin is 8 px or 12 px, and whether the image you exported matches the spec. This tool gives you those answers without switching applications.

For physical measurements on screen — where you want real-world units like centimeters or inches — the online ruler is the right companion tool. And if you need to convert between pixels, points, and physical units, the unit converter has all of those covered in one place.

How to Measure Pixels with This Tool

  1. Open or drag an image onto the canvas — a screenshot, mockup, or wireframe.
  2. Draw a selection rectangle by clicking and dragging over the element you want to measure.
  3. The width × height in pixels appears in real-time as you drag.
  4. Hover to see live x/y coordinates at any point, or click to pin a color.
  5. Use Export PNG to save a pixel-perfect crop with measurements overlaid.

Who Uses a Pixel Ruler?

Privacy and Security

Everything runs locally in your browser using the Canvas API. Images are loaded directly into a canvas element on your device — no upload, no server, no tracking of what you measure. PNG exports are rendered at the display native resolution for pixel-perfect crops.

Frequently Asked Questions

Yes. Pixel Ruler uses the device pixel ratio so measurements and PNG exports are accurate on both standard and high-density (Retina/HiDPI) displays.
No. Pixel Ruler runs entirely in your browser using the Canvas API. Your images never leave your computer.
Click any pixel on the canvas to pin its color, then use the popup copy button to copy the HEX or RGBA value instantly.
Yes. PNG exports are pixel-perfect crops from the original image with no compression or scaling applied.
Web designers, UI/UX developers, and QA testers use it to measure exact pixel dimensions on screen, verify spacing in CSS layouts, check image resolutions, and pick colors from designs.
The online ruler measures physical distances (cm, mm, inches) on your real-world screen. The pixel ruler measures in pixels — the unit used by CSS and screen design. Both tools serve different but complementary purposes.