How to measure an angle using a protractor

Protractor helps you to measure the angles in degrees. In this article, the students of 5th grade math can learn how to make a neat angle using the protractor. The symbol for degrees is a small circle °. A protractor has two sets of numbers from 0 to 180 and the other set from 180 to 0. In order to measure the angle with a protractor, the students must know what is a protractor. Read this page thoroughly to know how to find the angle with protractor with examples.

Do Refer:

What is a Protractor?

The size of an angle is measured using a protractor. The shape of a protractor is a semicircle. The semicircle is divided into two parts. The protractor has two sets of measurements. The first set is from 0° to 180° and the other set is from 180° to 0°. The marking on the inner circle is 0 degrees to 180 degrees in the opposite direction to the markings on the outer circle.

How to measure an angle using a protractor

How to Measure an Angle with a Protractor?

  • First place the midpoint of the protractor on the vertex of the angle.
  • Line up one side of the angle with zero lines of the protractor.
  • Read the degrees where the other side crosses the number line.

How to measure an angle using a protractor

Example: What is the measure of 90° in a protractor?

Measuring Angles with a Protractor Examples

Have a look at the below examples to see how to make a neat angle using a protractor.

How to measure an angle using a protractor

Example 1.
Use your protractor to draw 75°.
Solution:

1. The centre O of the piece is also the midpoint of its baseline.
2. To measure ∠AOB, place the protractor in such a way that its center is exactly on the vertex O of the angle, the baseline lies along the arm OA.
3. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.
Thus ∠AOB = 75°.

How to measure an angle using a protractor

Example 2.
Use your protractor to draw 120°.
Solution:

1. The center O of the piece is also the midpoint of its baseline.
2. To measure ∠AOB, place the protractor in such a way that its center is exactly on the vertex O of the angle, the baseline lies along the arm OA.
3. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.
Thus ∠AOB = 120°.

How to measure an angle using a protractor

Example 3.
Use your protractor to draw 35°.
Solution:

1. The center O of the piece is also the midpoint of its baseline.
2. To measure ∠AOB, place the protractor in such a way that its center is exactly on the vertex O of the angle, the baseline lies along the arm OA.
3. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.
Thus ∠AOB = 35°.

How to measure an angle using a protractor

Example 4.
Use your protractor to draw 15°.
Solution:

1. The center O of the piece is also the midpoint of its baseline.
2. To measure ∠AOB, place the protractor in such a way that its center is exactly on the vertex O of the angle, the baseline lies along the arm OA.
3. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.
Thus ∠AOB = 15°.

How to measure an angle using a protractor

Example 5.
Use your protractor to draw 50°.
Solution:

1. The center O of the piece is also the midpoint of its baseline.
2. To measure ∠AOB, place the protractor in such a way that its center is exactly on the vertex O of the angle, the baseline lies along the arm OA.
3. We need to read the mark through which the arm OB passes, starting from O on the side A, as we observe in the above figure.
Thus ∠AOB = 50°.

FAQs on Using a Protractor to Measure Angles

1. How do you use a protractor to measure degrees?

1. Place the midpoint of the protractor on the vertex of the angle.
2. Line up one side of the angle with the zero lines of the protractor.
3. Read the degrees where the other side crosses the number scale.

2. Do you use the inside or outside numbers on a protractor?

Both scales go from 0 to 180, but they run in opposite directions. If the angle opens to the right side of the protractor, use the inner scale. If the angle opens to the left of the protractor, use the outer scale.

3. What are the lines on a protractor called?

A straight line, which is displayed in the horizontal direction at the bottom of a protractor is called the baseline of the protractor.

This 4th grade geometry lesson explains angle measure, how to measure angles with a protractor, and has varied exercises for the students.

The video below explains what an angle measure is, how to measure angles with a protractor, and how to draw angles with a protractor.

Remember how one side of the angle traces out a circular arc? We use that circle to measure how big the angle is. We look at how much the angle has “opened” as compared to the full circle.

Angles are measured in degrees. The symbol for degrees is a little circle °.

  • The FULL CIRCLE is 360° (360 degrees).
  • A half circle or a straight angle is 180°.
  • A quarter circle or a right angle is 90°.

Show the angles below using two pencils. Try to “see” the circle that is traced out in the air.

This is a 1-degree angle!

How to measure an angle with a protractor:

  • Place the midpoint of the protractor on the VERTEX of the angle.
  • Line up one side of the angle with the zero line of the protractor (where you see the number 0).
  • Read the degrees where the other side crosses the number scale.

Take care to read from the right set of numbers. A protractor has two sets of numbers: one set goes from 0 to 180, the other set from 180 to 0. Which one you read depends on how you place the protractor: place it so that one side of the angle lines up with one of the zeros, and read that set of numbers.

In the examples above we lined up the one side of the angle with the zero of the lower set of numbers, so we need to read the lower set of numbers.

1. Measure the angles.

2. Measure the angles. Label each angle as acute or obtuse.

a. __________°

b. __________°

c. __________°

d. __________°

e. __________°

f. __________°

3. Tasha measured an acute angle, and got 146°. The teacher pointed out
that she had read the wrong set of numbers on the protractor.
What is the correct angle measure for the angle she measured?

4. Measure the following angles using your own protractor. If you need to, make the sides of the angles
longer with a ruler.

6. Draw four dots, and connect them so that you get a quadrilateral.
Measure all the angles of your quadrilateral. Then add the angle measures.
Did you get 360 degrees, or close?

How to measure an angle using a protractor

Math Mammoth Geometry 1

A self-teaching worktext for 4th-5th grade that covers angles, triangles, quadrilaterals, cirlce, symmetry, perimeter, area, and volume. Lots of drawing exercises!

Are your Year 5 maths learners battling their protractors in their angles lessons? Here’s a handy guide to help them measure angles with confidence.

Protractors may seem like innocuous semi-circles with some numbers marked around the outside. But they’re trickier than they look and can be hard for your learners to get to grips with.

If you’re tackling the angles lessons in Maths — No Problem! Textbook 5B, Chapter 9, or looking for general tips for teaching angles in Year 5, then keep reading.

Why do learners struggle to measure angles using a protractor?

My Year 5 maths learners started the angles chapter with good prior knowledge of the names and specifications of angles. This stood them in good stead for Lesson 1: Knowing Types of Angles.

But my class hit a speedbump in Lesson 2: Measuring Angles which focused on measuring angles within a polygon. The pace of the second lesson was fast, and it was clear that not all learners were making ‘expected progress’.

How to measure an angle using a protractor

Digging deeper, I could see that the practical skills needed to use a protractor to measure angles were causing confusion in my class. Children seemed to struggle to understand the difference between the ‘inside’ and ‘outside’ scales of the protractor and confused reflex and obtuse angles.

I realised that to address this, I’d have to break down the steps of measuring angles and slow things down for learners struggling with this aspect of the topic.

How to measure angles: a step-by-step guide

In the next lesson, I wrote down the steps of how to measure the angles on my whiteboard:

  1. Find the baseline of the protractor and line it up with the baseline of the shape or angle
  2. Place the midpoint of the protractor on the vertex of the angle
  3. Line up one side of the angle with the zero line of the protractor (where you see the number 0)
  4. Read the degrees where the other side crosses the number scale

After reading these instructions to my class, I decided to pop on my handy visualiser and told them we would be re-measuring all polygons from our workbook following the step-by-step instructions on the board. My learners moaned but I repeated my instructions until eventually everyone was on task and engaged in making corrections in their workbooks themselves.

Following that 20-minute recap, I felt the class could move on to the next lesson with greater confidence (as I had previously planned).

The third lesson set my learners up for even more angle-measuring practice and gave them some slightly more accessible shapes to measure. They also had the opportunity to measure angles on a straight line. This was something they really enjoyed, and they were keen to start using their newly-found protractor skills.

How to measure an angle using a protractor

What angle measuring resources can you use to teach angles?

Resources are always helpful for my class, especially if they are visual. To assist my learners in their understanding of angles, I have printed out and displayed the names and characteristics of the different types of angles with corresponding pictures.

We’ve also spent time examining our classroom and identifying how many right angles we can see. This visual aid has supported learners in their protractor-measuring journey.

I’m constantly reminding my class that angles are all around us! Another challenge I set was to find how many different types of angles they could find in everyday life outside the classroom: corner joints on furniture, corners of rooms, foil-wrapped cheeses, or indeed, straight lines.

At first, teaching angles proved to be difficult for some learners to access. But in the end, it provided them with an invaluable opportunity to see how angles are an intrinsic and important part of the real world.

Interested in learning more?

See how Maths — No Problem! can support your practice through award-winning textbooks and workbooks, step-by-step teacher guides, and online CPD videos.
Request School Demo

This is a transparent online protractor, also helps you measure angles in a picture, you can easily measure the angle of any object around you, taking a picture and uploading it, then dragging the midpoint of the protractor to the vertex of the angle.

How to use this online protractor ?

  • You can measure the angle of any actual object directly on your screen
  • If you want to move the protractor, drag the midpoint of it.
  • If you want the make the protractor smaller, change the protractor radius
  • You can rotate the protractor just like the traditional protactor
  • Click the edge outside of the protractor will add a pushpin on it
  • Placing two pushpins will show the degrees of that angle
  • Double-click on the pushpin will remove it
  • These actions can also be done in the buttons inside the control panel
  • The protractor can zoom in, zoom out and move the position
  • The background can be zoomed in and out
  • You can download your design and share to others
  • Mobile browsers don’t support drag action, just use buttons

Every time I want to measure the angle, I always can’t find the protractor. Fortunately, here is an online protractor that is convenient and practical. Now, we can use laptops, computers, tablets or smart phones to measure the angle of anything, around us anytime, anywhere.

If you want to measure something that is small, just place it on the screen and measure it directly; If you want to measure something bigger, you can take a picture and upload it, then move the center point of the protractor to measure its angle.

Use camera or image to measure angle

You can take picture of any object that you would like to measure, for example, a car, road, house, stairs or a mountain, the protractor is transparent, after you uploaded the image, it will be display in the background. then, you can drog the protractor or add pushpins to figure out the degrees of angles, upload file only accept image file in formats of jpg, gif, png, svg, webp.

In the control panel, if the background color is close to the protractor, and it’s not easy to distinguish, you can change a protractor color to see it clearly. Also you can move it, shrink or enlarge the size of protractor, according to your needs.

How to measure an angle using a protractor

Angles and Degrees

  • Angles are measured in degrees, the symbol for degrees is a little circle °
  • The full circle is 360° (360 degrees)
  • A half circle or a straight angle is 180°(180 degrees)
  • A quarter circle or a right angle is 90°(90 degrees)

How to measure an angle with a protractor

  • Place the midpoint of the protractor on the vertex of the angle.
  • Line up one side of the angle with the zero line of the protractor (where you see the number 0).
  • Read the degrees where the other side crosses the number scale.
  • Take care to read from the right set of numbers.
    A protractor has two sets of numbers: one set goes from 0 to 180, the other set from 180 to 0.
    Which one you read depends on how you place the protractor:
    place it so that one side of the angle lines up with one of the zeros, and read that set of numbers.

What do you think of this protractor ?

Thanks for your comments, I saw some people want to rotate it, so i added this feature, thank you all for your support, sharing and enjoy to use it.

Translate into your native language

We hope to provide a more user-friendly experience, are you willing to offer a native language version for your country ? We are looking for volunteer to improve the content in your native language, if you are interested to help this, please visit this translation page. Below are some other language version.

Online rulers

    : The most accurate size ruler on the web. : variable scale ruler with metric units(cm, m, km) : variable scale ruler with imperial units(in, ft, yd, mi)

Visit this page on your smartphone

Disclaimer:
Use of the protractor within this website is free. Whilst every effort has been made to ensure the accuracy of the protractor published within this website, you choose to use them and rely on any results at your own risk. We will not under any circumstances accept responsibility or liability for any losses that may arise from a decision that you may make as aresult of using this protractor. Similarly, we will not be requesting a share of any profits you may make as a result of using the protractor.

These are the tools you need to measure, lay out, and make accurate cuts of any degree.

Share this story

  • Share this on Facebook
  • Share this on Twitter

Share All sharing options for: Angle Measuring Tools

  • Pinterest
  • Email

How is it that finish carpenters do trim jobs daily without suffering angle-induced embolisms? Easy—because they rely on miter guides, not their eyeballs, to tell them where to cut. Likewise, framing carpenters use squares to determine the angles for rafters, rakes, and stair stringers; and furniture makers consult their protractors before laying out dovetails.

What Tool Do You Use to Find Angles?

The right angle-finding tool is your protection against loose joinery and expletive-filled outbursts, whether you’re doing something big like building a garden shed, or simply tackling around-the-house maintenance tasks like measuring for a storm window.

So before you make another unsightly cutting mistake, put down that caulk tube and pick up one of the measuring tools. The old adage—”Measure twice”—still applies. But you also need to know the angles.

10 Angle Measuring Tools

1. Pivot Square

The aluminum Pivot Square has a locking, adjustable leg that firmly holds any angle from 0 to 90 degrees, so you can make repeated, consistent mark or guide your circular saw through marks or guide your circular saw through angled crosscuts. Spirit vials help you check for level, as when establishing the angle to cut siding where it meets a roofline. About $84, C.H. Hanson

2. Three-Sided Squares

Photo by Mark Weiss

Simple, durable, and full of roof-layout info, the Speed square is a carpenter’s classic. Use it to find angles, mark cutlines, and as a crosscut guide to keep your saw straight. Stick with the aluminum alloy version, not plastic: It’s more rugged, and the stamped numbers are easier to read. About $10, Swanson Tool Co.

3. Square Shooter

Photo by Mark Weiss

This layout weapon for wide pieces of lumber has a sliding knob along its semicircular arc. Lock the triangle at the desired degree, then press it and a fixed knob on the handle against the edge of the work. The 12-inch blade can’t wobble or pivot as it guides your pencil or your saw.

4. T-Bevel

Photo by Mark Weiss

Lock the T-bevel’s sliding blade against any angle, then use the tool to copy that angle onto your work or to set the angle of a saw blade. This T-bevel’s blade locks in place with a recessed bronze latch (as opposed

to the usual wing nut) so either side can lie flush as you’re marking your layout.

5. T-Bevel Setter

Photo by Mark Weiss

T-bevels, which have no markings, are great for matching and transferring angles but can’t tell you exactly what those angles are. To find out, align the bar on this guide with the T-bevel’s blade and read the angle to half a degree. Or set a desired angle and align the bevel’s blade with it.

6. Bevel Protractor

Photo by Mark Weiss

Starrett’s cast-iron protractor head with chromed-steel rule, on the market since 1908, is a classic machinist’s tool for anyone who values precise layout marks. The rotating 180-degree head locks the rule at a desired angle or tells you the exact angle of an existing bevel.

7. Digital Protractor

Photo by Mark Weiss

Bosch’s digital angle finder is arguably the most accurate tool we tested, and certainly the most idiot proof. Press each of its legs into a corner and get a digital readout to a tenth of a degree. The tool comes with two vials so you can be sure it’s level on both sides of the corner as you take a reading.

8. Protractor Plus

Photo by Mark Weiss

Starrett’s updated combination protractor takes the guesswork out of cutting crown molding. Place each leg on an adjacent wall, and arrows at the pivot show the degree setting you need to make a butt joint, or the angle to miter each piece. Comes with a table of compound miter angles.

9. Miter Guide

Photo by Mark Weiss

Press this simple tool’s legs flush against any inside or outside corner. Internal gears position a protruding metal tab to bisect the angle. Now take the guide to your miter saw, brace one leg against the fence, then line up the saw blade against the tab. You’ve just set the exact miter angle.

10. Adjustable T-Square

Photo by Mark Weiss

Improving on the old 4-foot squares that could only mark 90-degree cuts in drywall, OSB, plywood, and other sheet goods, this adjustable square has markings for 30, 45, and 90 degrees. Or you can set it to any angle between 0 and 180 degrees. Folds for easy transport.

This animation illustrates how to use a protractor to measure an angle.

Click and drag the protractor and its blue handles to make some measurements.

A plan angle defines the space on the plan delimited by two crossing lines. The intersection of the lines is the tip of the angle.

The tool used to measure angles is the protractor. The most popular version is the half disc split into 180 equal parts that each correspond to one degree. The protractor is graduated from 0 to 180 degrees (°). Another form of protractors available would be the full disc graduated from 0 to 360°. To facilitate its usage, the protractor often possesses two graduations going in both directions.

The most common units of measures for angles are the degree (°) and the radian (rad).

Handling the protractor:

  • Position the origin of the protractor on the tip of the angle to measure.
  • Align the 0° graduation of the protractor with one of the side of the angle.
  • Read the graduation that follows the second side of the angle

Click and drag the protractor and its blue handles to make some measurements.

Learning goals

  • To teach how to place a protractor in order to properly measure an angle.
  • To be able to establish the measure of an angle by using its complementary (example of the javelin and of the inclined road).

Learn more

Units of measure of an angle:

If we were to share a circle in 360 equal sections, the degree is then the measure of the angle at the center formed by the delimiting sides of that section. This…

How to measure an angle using a protractor

Key Question: How can I use a protractor to measure angles?

How to measure an angle using a protractor

Learn how to solve these kinds of problems.

Welcome to this free lesson guide where you will learn how to read a protractor and how to use it to measure angles.

This complete guide on how to use a protractor includes several examples, an animated video mini-lesson, and a free worksheet and answer key.

Let’s get started!

Before we learn how to use the protractor tool to measure angles, let’s do a super quick review of angle notation (understanding this important skill will make learning how to use a protractor much easier).

Angle Notation: In geometry, an angle is denoted by the ∠ symbol and includes 3 consecutive letters which represent the three points that form the angle. Note that the middle letter denotes the vertex point of the angle.

For example, notice how in the diagram below that both angles ∠ABD and ∠CBD have point B as their vertex, but have different measures?

In this example, ∠ABD=120 and ∠CBD=60. But what happens when the angle measures are not included on the diagram? How can you find the measure of the angles in these kinds of situations?

Interactive activities are included to help you practice measuring angles with a protractor.

Measuring Angles

The size of an angle is usually measured in degrees (°). Think of a circle which is divided into 360 equal sectors. Each sector has a small angle at the center of the circle – the size of such angle is 1 degree (written: 1°). In other words, the size of an angle is a measure of how wide the angle is at the vertex bound by the two sides.

Given an angle ABC,

How to measure an angle using a protractor

How do we measure the size of the angle? We can measure angles using an instrument known as a protractor.

What is a protractor?

A protractor is an instrument used to measure the size of angles.

The protractor shown below has two scales:
The outer scale starts from 0˚ to180˚ going clockwise.
The inner scale starts from 0˚ to 180˚ going anti-clockwise.

How to measure an angle using a protractor

How to measure an angle using a protractor

To measure angle ABC , we need to:

Step 1: Place the center point of the protractor on the vertex B.

Step 2: Adjust the base line of the protractor so that it is aligned with the line BC

Step 3: Read the value of angle ABC, from the inner scale.

How to measure an angle using a protractor

We can also adjust the base line of the protractor so that it is aligned with the line AB and use the outer scale to measure the angle.

How to measure an angle using a protractor

How to measure and draw angles using a protractor?

The following videos will show you how to measure and draw angles using a protractor.

Measuring and Drawing Angles
How to measure angles and draw angles using a protractor?

Measuring angles using a protractor (acute angles)

Measuring Angles with Protractors (obtuse angles)

Activity Using A Protractor

Measuring Angles
Practice lining up and reading a protractor while you measure a set of angles in this fun learning activity. The angles may range from 0° to 180°.

How to measure an angle using a protractor

Try the free Mathway calculator and problem solver below to practice various math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

We welcome your feedback, comments and questions about this site or page. Please submit your feedback or enquiries via our Feedback page.