What is Ruler?

Ruler Meaning in Math - A ruler is a device or tool that is used in geometry and technical drawing, as well as engineering and construction technologies to measure the distance of a straight line. A math ruler is used to measure the length in both metric and customary units. The rulers are marked with standard distance in centimetres in the top and inches in the bottom and the intervals in the ruler are called hash marks.


Types of Ruler

There are different types of ruler depending on the material it is made of. Rulers are made from wooden, plastics and metal. Plastics are used to make ruler since they were invented as they could be moulded with the length markings. Material rulers are used at a mechanical workshop. Sometimes a metal edge is embedded into a wooden desk ruler to preserve the edge when used for straight-line cutting.

Depending on the size of the ruler there are two types of the ruler - a short ruler and a long ruler. Short rulers are 15 centimetres which are very convenient to carry and long rulers are 30 centimetres or 12 inches long, it is useful to draw larger drawings.

Line Gauge - This ruler is used in the paint industry and is made from a variety of materials, typically metal or clear plastics. The basic unit of measurement in the basic line gauge includes inches, agate, picas, and points.

Measuring Instruments - This instrument is made similar to the ruler function and they are portable by folding or retracting into a coil as in metal tape measure. When they are extended to use, It is straight as a ruler. For example, you can take a carpenter's ruler which is 2 m long and when it is folded, it's just 25 cm long, so that it can easily fit into the pocket.

Flexible Length Measuring Length - This instrument does not need to be straight, it is used by tailors to measure the fabric. The length of the tape is calibrated by inches and centimetres. It is used by a tailor to measure the solid body length, for example, a person's body. As well as linear length measurement for example a person's leg.

A Contraction Ruler - In this ruler there are larger divisions compared to the standard division, to allow the shrinkage of the metal casting. The contraction ruler is also known as the shrinkage or shrink ruler.

Screen Rulers - It is a type of ruler software programme, where you can have a digital scale on the screen by setting up the pixel. They are functional in both mobiles and the computer and it is useful in the absence of a physical ruler.


Measuring Objects Length Using Ruler


To measure the length of any object, primarily place the first hash mark (which is at Zero marking) of the ruler, exactly at one end of the object. Then set the object along the ruler and then finally note down the final hash marks, which is the endpoint of the object. Refer to the above diagram for a better understanding of the process.


Reading Ruler

Ruler Measurements in Centimetre - A ruler will be having centimetre and millimetre markings. A centimetre is smaller compared to the inch. The hash marks with numbers on the upper side represent the centimetre. The millimetre is smaller than the centimetre, the smaller hash in between centimetres is known as a millimetre.

10 millimetre is equal to 1 centimetre.



1/10 = One-tenth of the cm.

3/10 =  Three tenth of cm.

5/10 =  Five tenth of cm.

8/10 =  Eight tenth of cm.

1 is equal to 1cm.

Ruler Measurements in Inches - Inch is bigger than the centimetre. The big long hash with numbers opposite to the centimetre is known as the inches. There are a total of 16 sub hashes between the marking of one inch on the ruler.


Uses of Ruler

After going through what is ruler? We understood that ruler in maths is used to measure a line and the straight edges, which allows them to be used for drawing, scoring, and cutting. Many times they are also used in engineering, carpentry and the print fields.


Uses of Ruler in Geometry

In geometry, a ruler without having any marks on them could be used for drawing only a straight line between two points. It is also used to draw graphs and tables due to its straight edge.

It is used in the ruler and compass construction, where an unmarked ruler and compass can be used for construction. It is also useful in bisecting the angle by using an unmarked ruler and compass.


Do You Know?

Which is the largest preserved ruler? Copper alloy rod is the oldest preserved ruler from c. 2650 BCE and it was by the German Assyriologist Eckhard Unger while excavating at Nippur.

FAQs (Frequently Asked Questions)

1. How Wide is an Inch?

Answer. One inch (2.5 cm) is roughly equal to the measurement from the top knuckle on your thumb to your thumb tip. Measure and compare with one inch to check the difference between them. You can use your hand as a measuring guide for measuring items under 6 inches (15 cm).

2. Can we Measure with our Phone?

Answer. Yes, we can measure with our phone. By launching the measure application, then point the phone's camera at the object you want to measure. Then pick two points you want to measure the distance between them, the virtual tape measures either the height or length of the object. But always remember that the measurement done through the phone application is not always accurate.