Online Protractor

Measure angles on your screen. Place the virtual protractor over images, blueprints, or physical objects to quickly read the angle.

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How to Use the Online Protractor

Position the Protractor

Once the online protractor is open, move it to the area you wish to measure.
You can use it to measure images, shapes, documents, or any other content visible on your screen.

Align with the Vertex

Position the center point of the protractor over the vertex (the corner point) of the angle you want to measure.
Ensure the vertex is centered within the protractor to obtain an accurate reading.

Align with the Sides of the Angle

Adjust the position and orientation of the protractor so that its scale lines align with the two sides of the angle.
Once both sides are aligned with the markings on the protractor, you can read the angle measurement.

Read the Angle Measurement

Check the scale on the protractor to determine the angle between the two sides.
The online protractor supports the measurement of various types of angles, including acute, right, obtuse, and straight angles.

Measuring Angles of Physical Objects

In addition to measuring content on your screen, you can place physical objects next to the screen and use the on-screen protractor to check their angles.
Examples include: verifying angles in craft projects, comparing the angles of object edges, or referencing angles found in images or technical drawings.

Need More Flexibility?

If you need to measure angles in any orientation, try our three-point angle measurement tool. By fixing a vertex and dragging the two measurement arms, you can measure complex angles with greater flexibility.
Use the three-point angle measurement tool →

FAQ

Basic Usage

Can the online protractor measure angles on the screen?

Yes.
The online protractor helps you measure angles displayed on your screen—whether in images, design blueprints, web elements, or any other visible content.
Simply move the protractor to the desired location, align its center point with the vertex of the angle, and position the scale lines along the two sides of the angle to read the measurement.

How do I use the online protractor?

Using the online protractor takes just a few steps:
1. Move the protractor to the area you wish to measure;
2. Align the center point with the vertex of the angle;
3. Adjust the protractor so that its reference lines align with the two sides of the angle;
4. Read the displayed angle.
No software installation is required; simply open the webpage to start using it.

Does the online protractor require calibration?

No.
Unlike measuring length, measuring angles is based on geometric relationships and is independent of screen size, resolution, or display scaling.
Therefore, the online protractor does not require any screen calibration to measure angles.

Measurement-Related

What types of angles can the online protractor measure?

The online protractor can measure a variety of common angles, including acute angles (less than 90°), right angles (90°), obtuse angles (between 90° and 180°), and straight angles (180°). It is suitable for educational purposes, design work, image analysis, and everyday measurements.

Can the online protractor be used to measure physical objects?

Yes.
You can place a physical object next to your screen and use the online protractor as a reference tool for measuring angles.
For example, it can be used for comparing angles in craft projects, checking the angles of furniture or object edges, or determining angles found in images or technical drawings.

What units of measurement does the online protractor support?

The online protractor uses degrees (°) as its unit of measurement.
For example: 45°, 90°, 120°. All measurement results are displayed in degrees.

Functionality

What is the difference between an online protractor and a physical protractor?

An online protractor functions similarly to a physical one: you align the center point with the vertex of the angle and read the measurement from the scale.
The key difference is that an online protractor appears directly on your screen, making it convenient to measure angles in images, web content, or digital design files.

Can I open the protractor in a separate window?

Yes.
By opening it in a separate window, you can move the protractor anywhere on your screen, making it easy to take measurements while referencing images, documents, or other content.
Open the protractor in a separate window →

Can I measure angles in any orientation?

Yes.
You can measure angles in various orientations by adjusting the position and rotation of the protractor.
For greater flexibility when measuring the angle between any two lines, you can use the three-point angle measurement tool.

Data and Privacy

Does the online protractor collect my data?

No.
The online protractor does not require you to upload your images, measurement data, or personal information. Your measurements are performed entirely within your browser.