Online Protractor

An angle is measured in degrees between two lines that meet at a point called the vertex. Place the center of your measuring tool on the vertex, line one side up with the zero mark, and read where the second side crosses the scale. With this online protractor you simply drag the movable arm onto the second line and the live degree readout shows the answer instantly.

Put the center hole of the protractor exactly on the vertex, then align one side of the angle with the zero baseline. Read where the second side crosses the curved scale, and that number is your angle in degrees. This online protractor tool handles the fiddly alignment for you: the vertex and baseline stay fixed, so you just swing the highlighted arm onto the second line and read the result.

You can estimate one against a known reference, like the square 90° corner of a sheet of paper, or work it out with trigonometry if you know the side lengths. Those methods are either rough or fiddly. The easier route is to measure the angle online here by dragging the arm to match the angle, giving you an exact reading without any physical tool.

Yes. Tick Move vertex and drag the center point over the corner in your on-screen photo, diagram or drawing, then swing the arm along each side to read the angle between them. It is a fast way to measure the angle of something in an image that you cannot reach with a real protractor, all inside your browser.

A protractor is a measuring instrument, usually a flat half-circle marked from 0° to 180°, used to measure and draw angles. Traditional ones are plastic or metal, while a digital version like this online protractor lives on your screen and calculates the angle mathematically. Both do the same job: tell you the number of degrees between two lines.

Angles are grouped by size: an acute angle is under 90°, a right angle is exactly 90°, an obtuse angle is between 90° and 180°, a straight angle is 180°, and a reflex angle is over 180°. Because this tool reads the full 0 to 360° range, you can drag the arm around and watch each type appear in turn.

On a physical protractor with two rows of numbers, use whichever scale starts at zero on the side you lined up your baseline with, then read along to the second line. A handy check is your estimate: an acute angle should give the smaller number and an obtuse angle the larger one. This online protractor avoids that confusion entirely by showing a single, unambiguous degree readout.

Yes. It is useful for checking miter and bevel angles, verifying a slope or roof pitch, or reading a corner from a photo before you cut. Remember that for an outside or inside corner you usually halve the measured angle to get the miter-saw setting, so a 90° corner becomes a 45° cut. Use the online protractor tool here to confirm the angle, then transfer it to your saw.

This widget is built for measuring the size of an existing angle rather than drawing on paper. That said, you can set a precise target value, for example with Snap 1° turned on, note the direction the arm points, and mark that line by hand to recreate the angle. For pure on-screen measurement it is ready to go immediately.

Yes on both counts. The angle is computed from the arm position and reported to one decimal place, so it avoids the parallax and misalignment errors of eyeballing a plastic protractor, and it is completely free with nothing to install or sign up for. That makes it a dependable online protractor for students, hobbyists and anyone who needs a quick, exact angle.