There are two types of ruler: the Anglo-Saxon or fractional one and the metric one with a decimal base. Reading this tool might seem complex because of all those little lines, but it's actually quite a simple process. Once you understand the basic concepts described in this tutorial, you won't have any difficulty taking measurements with either type of ruler.
Steps
Method 1 of 2: Read an Anglo-Saxon Ruler
Step 1. Get an instrument with a British imperial scale
You can understand that it is this type of ruler because it has 12 lines indicating inches, so the tool is 1 foot (30 cm) long. The entire length of the tool (1 foot) is divided into inches. In turn, each inch is divided into 15 smaller notches, so in the space of each inch you can find 16 notches in all.
- The greater the length of a notch on the ruler, the greater the corresponding measurement. As you go from 1 inch to 1/16 inch, the size of the lines decreases proportionally to the unit of measurement.
- Remember to read the ruler from left to right. If you need to detect the size of an object, align its edge with the left side of your tool. Where the right edge of the object meets a notch on the ruler determines its measurement in inches.
Step 2. Learn to read the thumb marks
A standard ruler is divided into 12 marks that indicate inches. These are typically numbered and also represent the longest notches on the tool. For example, if you need to measure the length of a nail, place one end of it on the left side of the ruler. If the right end of the nail ends exactly at the long notch indicated by the number 5, then you can say it is 5 inches long.
Some graduated lines also have the numbers corresponding to the "half inch", so be careful to take into account the longer notches that indicate the inches
Step 3. Recognize the 1/2 inch notches
They should be the second in order of length, among those present on the instrument, and correspond to about half the notches of the thumbs. Each half-inch line is halfway between two numbers, precisely because it indicates 1/2 inch. In other words, you will find a notch between the number 0 and 1, between 1 and 2, between 2 and 3 and so on along the entire length of the instrument. In all there are 24 notches of this type.
For example, place the ruler next to a pencil with an eraser so that it coincides with the left edge of the tool. Check which notch on the ruler matches the tip of the pencil. If it is a shorter line, halfway between the 4 and 5 inch lines, then the pencil is 4 1/2 inches long
Step 4. Recognize the ¼-inch notches that are midway between a half-inch and a full-inch line
These notches are even shorter. In the space corresponding to the first inch, these lines denote 1/4, 1/2, 3/4 and 1 inch. Although the half-inch and full-inch values are already indicated by their specific notches, they are still within the quarter-inch scale, as 2/4 of an inch is 1/2 inch and 4/4 of an inch is equivalent to 1 inch. A scale graduated according to the British imperial system shows 48 notches of this type.
If you were to measure the length of a carrot and its tip fell at the line halfway between 6 1/2 "and 7" inches, then you would know that the vegetable is 6 3/4 "long
Step 5. Learn to distinguish the 1/8 inch notches
These are even smaller and are located between two consecutive lines indicating 1/4 inch. Between the value 0 and 1 you can find the lines of 1/8, 1/4 (i.e. 2/8), 3/8, 1/2 (4/8), 5/8, 6/8 (3/4), 7/8 inch and 1 (or 8/8) inch. There are a total of 96 notches on the ruler which equate to 1/8 of an inch.
Suppose you want to measure the length of a piece of fabric whose end falls on the sixth line after the one that indicates 4 inches, that is, between the 1/4 and 1/2 inch mark. This means the fabric is 4 3/8 inches long
Step 6. Identify the marks corresponding to 1/16 of an inch
These small lines are located halfway between two consecutive notches that determine 1/8 of an inch. These are the shortest lines on the entire ruler. The first mark on the left end of the tool is 1/16 of an inch. Between 0 and 1 there are notches indicating 1/16, 2/16 (i.e. 1/8), 3/16, 4/16 (i.e. 1/4), 5/16, 6/16 (3 / 8), 7/16, 8/16 (1/2), 9/16, 10/16 (5/8), 11/16, 12/16 (3/4), 13/16, 14/16 (7/8), 15/16, 16/16 (i.e. 1) of an inch. On a standard ruler you can find 192 small sixteenth note lines.
- For example, you want to detect the length of a flower stem and its end corresponds to the eleventh notch after the one that indicates 5 inches. At this point you can say that the stem is 5 11/16 inches long.
- Not all rulers are graduated up to sixteenths. If you need to take the measurements of such small objects or you need to be very precise, make sure that your instrument also shows these marks.
Method 2 of 2: Read a Metric Ruler
Step 1. Get a scale ruled according to the metric system
In this case the unit of measurement is not represented by inches, but by centimeters. A standard ruler is 30 cm long, each of which is indicated by a large number. The space of each centimeter should be divided into 10 smaller notches which identify millimeters (mm).
- Remember that you have to read the tool from left to right. When measuring an object, align its edge with the left end of the scale. The notch on the ruler corresponding to the right end of the object indicates its length expressed in centimeters.
- Unlike the British imperial system, the metric ruler expresses values as decimal numbers and not fractions. For example, to indicate 1/2 centimeter we write 0, 5 cm.
Step 2. Recognize the centimeter marks
The large numbers written next to the longest lines of the instrument indicate centimeters. A graduated ruler typically has 30 such marks. You can line up the end of a crayon with the left edge of the tool to measure it. Look at the notch corresponding to the tip of the pastel; if it is a long line indicated with the value 14, then the crayon is 14 cm long.
Step 3. Identify the 1/2 centimeter marks
Halfway between one centimeter line and the other you can see a slightly shorter notch that denotes half a centimeter, i.e. 0.5 cm. There are 60 such lines on a standard ruler.
For example, if you wanted to know the diameter of a button and its edge fell on the fifth line between the 1 and 2 cm marks, then you would know that it is 1.5 cm
Step 4. Learn to recognize the millimeter marks
Between two consecutive 0.5 cm marks there are four more small lines indicating millimeters. For each centimeter there are 10 lines of millimeters and the 0.5 cm line also represents the 5 mm line; consequently each centimeter is 10 mm long. There is a total of 300 mm on a 30 cm line.
For example, suppose you want to measure a sheet of paper whose end falls on the seventh mark between the notches of 24 and 25 cm. This means that the sheet is 247 mm long, i.e. 24.7 cm
Advice
- It takes practice to learn how to read a ruler, especially to convert numbers to units of measurement. You just have to practice and eventually you will get better.
- Make sure you always use the correct side of the ruler, based on the project you need to complete. You don't have to mix centimeters with inches, otherwise you will get wrong measurements. To help you, remember that the side of the metric system has 30 large numbers, while the one with the British imperial system has 12.
