Ruler (cm/mm) online

Click ruler to get length:

JustFreeTools provides you with an easy to use, free printable online ruler that will save you to ever look for a ruler again! For Letter as well as A4 sized paper, inches as well as centimeters. Due to the easy fold mechanism on the sides, the paper ruler can be used for measuring and drawing as well. 

Some cool facts about rulers you probably didn't know!

The Invention of the First Ruler

In the past, humans have used body parts as ways to measure distances or objects, for example, a hand or foot. The first noted ruler in history, however, dates back to 2650 BC. The first ruler did not look like the ones we have in our stockroom. The first ruler was actually a copper alloy rod; however, there were rulers made of ivory in 1500 BC.

The Metric System

The metric system is the decimal measuring system based on the litre, metre and gram as units of capacity, length and weight/mass. In 1799, the metric system was introduced as the existing system was impractical for trade during the French Revolution. The idea was first proposed in 1670; however, it was only standardised in the 1790s, by the French.

The metric system was then introduced into the UK at the start of 1965.

Different Forms of Rules

The wooden ruler dates back to the 16th Century; however, we now have different forms of rulers. For example, we have metal, wooden, rubber and folding rules to use. The first folding ruler was created in 1851 by Anton Ullrich. The first flexible ruler, however, was invented back in 1902 by Frank Hunt.

Other forms of rulers include a desk ruler, a steel ruler, a carpenter's rule, a seamstress tape and even a tape measure.

Uses of a Ruler

A ruler has had many uses throughout history but has always been a prominent tool in Geometry. Different types of rulers can be used in different industries, for example, in tailoring, software, architecture, design and more. The printing industry and other industries utilise different types of rulers as well. The most notable use of a ruler, however, is in office spaces and schools. A pencil case for school, college or university is not complete without a durable and reliable ruler.


How to Read a Ruler in Centimeters

This is especially important to know if you’re studying science (recall that science generally uses the metric systemnot the imperial system). Knowing how to read a ruler in cm is also helpful for people who'd prefer to not work with fractions (which you must do with inches) and who'd like to work with other units instead (in this case, millimeters).

The standard metric ruler is 30 cm long. Each centimeter is labeled with a number to show the measurement it's referring to. You might see inches on the other side of your metric ruler. In this case, refer to the instructions above to learn how to read a ruler in inches.

Also, be aware that 30 cm does not directly equal 12 inches, even though they are often put on the same ruler!

Like the inches ruler, you’ll see tons of lines on a metric ruler, with some longer and some shorter. Each line represents 1 millimeter, which is equal to 1/10 or 0.1 cm (so 10 mm make up 1 cm).

There will always be 10 lines from one centimeter to the next centimeter. In total, there are three different lengths of lines on a metric ruler.

The longest line represents the biggest unit on the ruler: 1 cm. Each centimeter is labeled on the ruler (1-30).

While reading cnetimeters or milimeters, it is important to remember that every line from 0 would equal the following:

  • 1 mm (0.1 cm)
  • 2 mm (0.2 cm)
  • 3 mm (0.3 cm)
  • 4 mm (0.4 cm)
  • 5 mm (0.5 or 1/2 cm)
  • 6 mm (0.6 cm)
  • 7 mm (0.7 cm)
  • 8 mm (0.8 cm)
  • 9 mm (0.9 cm)
  • 10 mm (1 cm)

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And we are still developing more. Our goal is to become the one-stop, go-to site for people who need to make quick calculations or who need to find quick answer for basic conversions.

Additionally, we believe the internet should be a source of free information. Therefore, all of our tools and services are completely free, with no registration required. We coded and developed each calculator individually and put each one through strict, comprehensive testing. However, please inform us if you notice even the slightest error – your input is extremely valuable to us. While most calculators on Justfreetools.com are designed to be universally applicable for worldwide usage, some are for specific countries only.


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