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How is a Ruler Different From a Straight Edge

How is a ruler different from a straight edge?

A ruler is a straight edge, but all straight edges aren’t rulers. A ruler is different from a straight edge because it’s marked with inches and centimeters. Straight edge tools help you draw a perfect line but don’t always contain measurements. 

Craftsmen, woodworkers, and architects use straight edges and rulers to get perfect lines. At home, it’s likely you’ll choose to use a ruler, but you may start to wonder how a ruler is different from a straight edge.

Knowing the difference will help you decide which tools you need for your projects. 

Luckily for you, I’ll show you the difference between a straight edge and a ruler. I’ll show you how to determine if your ruler is straight and help you figure out what you can use as a straight edge.

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How is a ruler different from a straight edge?

A ruler is different from a straight edge because it’s used to make measurements. Straight edges are rulers with no markings. 

A ruler is a straight edge because it can draw a straight line. Straight edges make straight lines, but can’t always be used to make measurements. 

When crafting you will come across projects that require a straight line. To make the straight line, you can use a ruler or anything with a straight edge. Straight edges can also be used to check if a surface is flat. 

They are used for precision projects for crafts, architecture projects, or woodworking. You may even have a leveler in your tool shed to help with construction projects. The leveler that’s used to hang shelves or pictures straight is considered a straight edge. 

A ruler is a straight edge as well, but it’s marked on parallel sides with measurements. Usually, the measurements are inches, millimeters, or centimeters.

Rulers and straight edges come in different shapes and sizes, but will all produce a straight line. While you may be used to a long rectangular ruler, you can also find “set square” triangle-shaped rulers as well.

What is a straight edge?

A straight edge tool is used to draw a straight line or discover a flat surface. Objects that are considered straight edges are also used to lay out reference points or make precision cuts. 

Straight edges work for leveling, as cutting guides, or copying a straight line from one place to another. You can use straight edges to check lines you’ve already drawn or see if a previous job is straight.

Straight edges are rulers without their stripes. They’re long objects made of wood or aluminum. Some straight edges are long straight pieces of material shaped like a rectangular or triangular prism similar to rulers. 

Using a straight edge isn’t limited to drawing a straight line. Many projects need to be level, so straight edges and levelers are used to determine if a project is balanced. A straight edge can help you draw a straight line and also determine if the flooring in your living room is level.

Is a ruler straight?

A ruler is straight. Rulers are straight edges with measurements. The exceptions are flexible craft rulers that can fold to measure something round like your waist. 

With the exception of measuring tape and other flexible craft rulers, most rulers are straight.  Depending on the material, your ruler may change over time. Rulers made of porous wood can change shape and may not be straight when you’re ready to use them. 

How do you tell if a ruler is straight?

One quick way to tell if a ruler is straight is to test it by drawing lines. Another way to tell if a ruler is straight is to make measurements. A straight line will always be measured at 180 degrees.

1. Draw a line on wood

The quickest way to tell if a ruler is straight is to take a piece of wood and a sharp pencil and draw a line. Flip the ruler against the line and check to see if the ruler or straight edge follows the line. Wood sometimes works better than paper because the wood can’t bend or fold the line.

If the ruler is straight it will follow the line straight across on both sides. If it’s not straight, part of the line may be covered or there may be a dip or curve between the line and the straight edge.

2. Draw overlapping lines on paper

Another way to tell if a ruler is straight is to draw a line on a sheet of paper. Flip the ruler and draw another line across the same line. On paper, it may work better if you use a different color to compare lines. 

If the lines overlap completely then the ruler is straight. However, if the lines create a convex lens shape then the ruler is not straight. Each end of the ruler may be at a slightly different angle.

3. Create a straight edge to compare 

The simplest way to tell if a ruler is straight is to use a folded piece of paper. A folded piece of paper will give you a straight edge to compare your ruler to. Line your paper up with the edge of the ruler to see if it follows the straight edge.

What can I use for a straight edge if I don’t have a ruler?

If you don’t have a ruler use paper or a string to make a straight edge. Homemade rulers can be used by simply folding a piece of paper or pulling a string.

When a string is pulled it will make a straight line. A chalk line tool or reel is made with this in mind. The reel helps you measure using a straight line with a string covered in chalk. When you pull or pop the string against a hard surface it will leave behind a straight line.

Here are a few other homemade items to try:

  • Popsicle sticks
  • Wood stirrers
  • Cardboard 
  • Credit card
  • Cardstock/ Greeting Cards
  • Envelope

If you don’t have a ruler you can also use a straight edge tool. Straight-edge tools can be found in any craft or hardware store. You can also find rulers and straight edges online.

Summary: How is a ruler different from a straight edge?

Now you know a ruler is different from a straight edge based on measurement. You can find a straight edge tool that doesn’t have measurements to finish your project. You’ll want to use a ruler if you do need to measure. 

You can use other tools for crafts requiring a straight edge. Use a folded piece of paper for a straight edge if you don’t have a ruler. Common objects around the house like credit cards, popsicle sticks, or envelopes work if you don’t have paper. Depending on how big the project is you can even use a leveler. 

Test your straight edge if you aren’t sure it’s straight, by drawing straight lines on paper. Once you’ve drawn a few you can measure and compare the lines to see if they are straight. A straight line will always be 180 degrees. 

No need to worry now if you have what you need to make a straight line, you have the tools you need to keep you on the straight edge.