How to Read a Ruler

In this article, you will learn how to read an imperial ruler: halves, fourths, eighths, and sixteenths. It is super easy, I promise!

When I started learning how to sew, I was surprised that: Basic math skills like understanding all those tick marks on a ruler played a part in the construction of garments.

Yes, if you want to unleash your dressmaking superpowers, you must have a basic knowledge of fractions and geometry.

And you need to know how to read a ruler.

You need to know things like…

Yep! Surprising!

But don’t you fret! Because what we need to know is very simple and not hard at all.

I promise you that once you’ve used your ruler or measuring tape in a few projects, you’ll be thinking to yourself, “That was so easy! Why ever was I afraid?”

First, you should know that the two most common measurement systems are the Imperial System (fractions, inches, feet) and the Metric System (centimetre, millimetre, and metre).

In the U.S. (I know), we use the Imperial System of measurement, rather than the Metric System.

So if you’re ready, let’s do this…

How to Read an Imperial Ruler

An inch can be divided into 8, 16, or even 32 parts. In this article we will learn how to read an inch that has been divided into 16 parts.


The longest lines on a ruler or tape measure represent the inch markings — for example, 1 inch, 2 inches, 3 inches, and so forth:


Each inch can be further divided into half, which is represented by the second-longest line. This gives us a ½ inch:

How to Read an Imperial Ruler


And each ½ inch can be divided in half to give us fourths: ¼, 2/4, and ¾. See in the image below…

How to Read an Imperial Ruler

Did you notice how the ½ inch mark is now 2/4?!


Now, if we divide each fourth in half, we get eighths: 1/8, 2/8, 3/8, 4/8, 5/8, 6/8, and 7/8!

How to Read an Imperial Ruler

Did you notice how the ½ inch mark is now 4/8?!

Okay, I think you’re probably beginning to see a pattern!



We down to, yes, you’ve guessed it, sixteenths: 1/16, 2/16, 3/16, 4/16, 5/16, 6/16, 7/16, 8/16, 9/16, 10/16, 11/16, 12/16, 13/16, 14/16, and 15/16!

Yep, this is what we get when we divide eights in half. These will include the shortest lines on the ruler.

How to Read an Imperial Ruler

And in case you missed it, 2/16 is equivalent to 1/8 inch; 4/16 is equivalent to ¼ inch; 8/16 is equivalent to ½ inch; and so forth…

What did I tell you?!

Easy, right!

Sew easy tip: Grid rulers are conveniently divided into eighths and sixteenths. And these rulers are lifesavers when it comes time to adjusting our sewing patterns to achieve a good fit!

3 Essential Sewing Measuring Tools

Well, that’s it!

RELATED: Click HERE to learn the three essential measuring tools a dressmaker must have!

The End

When you started this article, you probably had no idea what every slash on an imperial ruler meant.

And now you do!

Yes, you actually know what all those slashes on an imperial ruler mean!

And remember…

Life is the ultimate red carpet event. Dress for it!

RELATED: Click HERE if you’re ready to unleash your dressmaking superpowers and learn how to sew a simple dress! Warning: This is a MEGA 5-part series!