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Online protractor

Drag the arm to set any angle from 0° to 180° and read it instantly. It's handy for a quick check on screen — but a screen protractor can't touch the real world. For angles on a wall, a workpiece, or a roof, the iPhone app reads them straight from the phone's sensors.

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Drag the orange handle to set the angle.

When a screen protractor is enough — and when it isn't

An online protractor is perfect for measuring an angle in an image you can drop on screen, teaching how angles work, or a quick sanity check. What it can't do is measure a real object: you can't lay your monitor against a table leg or a roof. That's the gap the Protractor app fills — rest your iPhone on the surface and it reads the angle from the same sensors behind Apple's level. For the underlying method, see how to measure an angle and how to use a protractor.

An online protractor for students and teachers

A virtual protractor is a clean way to learn how angles work. There's no parallax error from reading a printed scale at an angle, the value updates as you drag, and it's the same on every device — useful for classrooms, homework, and quick practice. Use it to check an answer, demonstrate acute versus obtuse angles, or measure an angle in a diagram on screen. When you're ready to measure angles out in the world, see tools to measure an angle and the angle finder app.

FREQUENTLY ASKED QUESTIONS

How do I use the online protractor?

Drag the orange handle around the dial to set any angle from 0° to 180°, and read the value live above the protractor. Click anywhere on the arc to jump the arm there. It works with a mouse or by touch on a phone or tablet.

Is this online protractor free?

Yes. The online protractor runs entirely in your browser, with no sign-up, no download, and no ads. It’s handy for students, teachers, and quick on-screen checks. To measure real-world angles, the free iPhone app reads them from the phone’s sensors.

Can I measure an angle in an image with it?

You can use the on-screen protractor to estimate an angle against anything on your screen, including an image placed behind the window. For measuring an angle on a real object or a photo you take, the Protractor iPhone app with camera mode is more accurate.

Is a virtual protractor accurate enough for school?

Yes — for learning how angles work, practising measurement, and checking homework, a virtual protractor is ideal because the readout is exact and there’s no parallax error from reading a printed scale by eye.

Can an online protractor measure a real-world angle?

No. A screen protractor can’t touch a wall, a workpiece, or a roof. For real surfaces, rest an iPhone on them and the Protractor app reads the angle from the same sensors behind Apple’s level — in degrees, percent slope, or a ratio.

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Measure any angle,
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Protractor turns your iPhone into a precision angle finder, level and inclinometer. Measure anything, anywhere.

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