How do I paste a screenshot into the pixel ruler?

Take a screenshot using your OS shortcut (Print Screen on Windows, Cmd+Shift+4 on Mac), then press Ctrl+V (Cmd+V on Mac) while on the tool page. You can also drag and drop image files directly onto the canvas.

Can I measure angles between lines?

Yes! Switch to Angle mode and click three points on your image. The tool calculates and displays the angle at the middle point in degrees.

Does the ruler support unit conversion?

Yes. You can set your screen DPI and convert measurements between pixels, inches, centimeters, and millimeters. The default is 96 DPI, which is standard for most displays.

How do I calibrate the ruler to real-world units?

Click the Calibrate button, then click two points spanning a length you already know (for example a ruler or a 1-inch object in the screenshot). Enter the real length such as 1 in, 2.54 cm, or 25.4 mm, and the tool computes the correct DPI so all measurements convert accurately.

Can I save my measurements?

Yes. You can export the annotated screenshot as a PNG file with all measurement overlays, or export your measurement history as a CSV file for further analysis.

Is there a zoom feature for precise measurement?

Yes. Use the zoom controls or mouse wheel to zoom in up to 800% for pixel-perfect precision. A magnifier loupe also follows your cursor showing a magnified view of the area around it.

Free Online Screen Pixel Ruler (No Signup)

Paste a screenshot (Ctrl+V) or drag & drop an image

Supports PNG, JPG, BMP, WebP, and GIF

Cursor Position

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Move cursor over image

Measurement

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Click points to measure

Color

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Hover to preview, click to pick

Image

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Measurement History

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📐 Screen Pixel Ruler

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Measurement

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Image

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Measurement History