One type regularly used in the US is the standard 12-inch ruler. Such rulers use inches, feet, and yards to measure the length of objects. They’re referred to as imperial rulers.
Another ruler type is the metric ruler, which uses millimeters, centimeters, and meters as its measurement units.
Note that the metric system is commonly used in more countries around the globe than the imperial system.
Some rulers can be available as only metric or imperial, then there are those that come with both measuring systems printed on the two edges lengthwise.
There are several types of rulers available, such as:
Metal or wooden rulers
Seamstress and measuring tapes
Architect and engineer scales
Folding rulers, aka carpenter rulers
Standard Imperial Rulers
Imperial rulers are one foot long, or 12 inches. When you put three of them together and lay them end-to-end, you get a yardstick, or 36 inches. When you reach a length of 1760 yards, you get one mile.
On almost all standard 12-inch rulers, you’ll get the word ‘inch’ printed out at the ‘0’ line. Then, you have clear markings for the numbers one to 12.
In between each of these numbers are 15 smaller markings. Half-way between each inch is the longest of these markings. It marks the halfway point.
To the left and right of this halfway point are the quarter and three-quarters markings. Then, between these are marks that start from 1/16 of an inch and go up to 15/16. This means that each inch is made up of 16 markings and each marking represents 1/16th of one inch.
Markings on an Imperial Ruler
Here’s what each of the markings stands for on an imperial ruler for starting at 0:
2/16 = 1/8 of an inch
4/16 = 1/4 of an inch
6/16 = 3/8 of an inch
8/16 = 1/2 of an inch
10/16 = 5/8 of an inch
12/16 = 3/4 of an inch
14/16 = 7/8 of an inch
16/16 = 1 inch
Metric rulers are 30 centimeters long. They have ‘cm’ written next to the ‘0’ line and consist of 9 small markings between each centimeter. This means there are 10 millimeters in each centimeter.
Each line stands for one millimeter. The fifth marking is the longest of all nine. It marks the halfway point between every two centimeters.
In the metric system, 100 centimeters equals one meter, and 1000 meters is equal to one kilometer. There’s even a meter stick that makes measuring longer objects more manageable.
Markings on a Metric Ruler
Here’s what each marking on a metric ruler stands for starting at 0:
1mm = 0.1 cm
5mm = 0.5 cm
10mm = 1 cm