How to Read a Ruler

ScienceStruck Staff Oct 25, 2018
Reading a ruler is a basic and an important measurement skill, which most of us are well aware of. However, there are many people who find it an intimidating task. For such people, here are a few simple instructions on how to read a ruler.
A ruler is a standard measurement tool used to read measurements of length in either the metric system (meters, centimeters, or millimeters) or the English (miles, yards, or inches) system. It is made of a number of materials like wood, metal, and plastic.
It is often 12 inches (1 foot or 30.48 centimeters) long with varying thickness. The markings which are used for measurements can be seen on its sides. In some, you can see the two measurement systems on different faces, while in others, the markings can be on the same face but on different sides.
Whether you are studying or working, a ruler is a valuable tool, that is used by most of us in our daily lives. From a simple task like drawing a line, to complicated measurements, it comes handy in all such situations. However, if you don't know how to read it correctly, this art of measuring things may seem to be a complete mystery.

Reading a Metric Ruler

A ruler using metric measurements mainly deals with centimeters and millimeters and no fractions are involved. Hence, it is fairly easy to read it. If you see its surface, the larger lines with numbers on it are centimeters, and the smallest lines are millimeters.
As millimeters are 1/10th of a centimeter, when you measure 7 marks after a centimeter, it is said to be 1.7 centimeters long.
Materials Required
  • 12 inch ruler
  • Piece of paper
  • Pencil
Steps to be Followed

1. First, find out the metric system side of the ruler. Either it will be written on the side or you can figure it out through the markings on the face. Since a centimeter is less than a inch (1 inch = 2.54 centimeters), the distance between lines would be smaller than the other side.
2. Further you can see, there are 9 lines between each centimeter and each line represents one millimeter. Hence, there are 10 millimeters in one centimeter.

3. Now, mark two points on a piece of paper, and join them with a straight line, keeping in mind that the line doesn't exceed the length of the ruler.
4. Keep the ruler besides the line and put its beginning at one end. See the number on the surface where the line ends and note it down. If in case, the line stops between two numbers, note the lower number, i.e., if the line stops between 8 and 9, note down 8 and this will be the measurement in centimeters.
5. Now when the line ends between two numbers, make a note of the markings between the two numbers, as it refers to a measurement in millimeters. Suppose the end of the line lies on the sixth mark, it means there are six millimeters between your mark and the big number.
6. Finally, combine the two measurements, and you got to have the exact length of the line. Considering the example, the length of the line is 8 centimeters and 6 millimeters, and you can write it in decimal form as 8.6 cm.

Reading Measurements in Inches

Reading a ruler that uses the English system or inches is apparently a bit difficult and requires a basic knowledge of fractions. However, here are a few simple instructions that will surely ease your task.
Materials Required
  • 12 inch ruler
  • Piece of paper
  • Pencil
Steps to be Followed

1. Find out the side that has the markings in inches, i.e., the side that has main numbers 1 to 12.

2. Now, make a line, and mark the number on the point where your line ends. The line may end exactly on one of the big numbers or somewhere in between two big numbers. If it ends between two of the big numbers, note down the smaller one.
3. Start counting the smaller lines between the big numbers and you will observe there are seven lines in between the markings for inches. Each of these small marks equal to 1/8 of an inch.
4. To calculate the exact length of the line, combine the two numbers. Now, suppose the end point of your line lies between six and seven and at the first mark of the smaller line, your measurement would be 6 and 1/8 inches.
Simple, isn't it? While measuring, hold the ruler steady, or else you will end up taking inaccurate measurements.