How to Read a Ruler

How to Read a Ruler

How to Read a Ruler

Author’s Note: This consists of a Video Tutorial and a Textual Explanation. If pressed for time, you are encouraged to bookmark this page and come back to take in both.

Note 2: You can skip this intro, if you wish and scroll right down to the “Let’s Get Into It” Header for the ‘meat and potatoes’ portion of the discussion.

Some people are not comfortable taking measurements with a ruler or using a measuring tape. The inch marks are pretty easy -but, what about all those ‘little marks” between the inch markers.  What in heck do they mean?

You will see that it’s not difficult to understand.  In fact, you probably learned how to read a ruler in elementary school and have since forgotten, if you haven’t needed to use the knowledge.  As with most things we learn -if we don’t use it we lose it.  

What follows is what I’ll call a refresherfor people who haven’t needed to know up to this point and would now like to awaken that lost knowledge and develop that skill.

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You Are Not Expected To Know

As a tradesman, it is second nature to me.  There was a time when I had to develop that skill.   Until I did, there was considerable fumbling going on, as well as many bad measurements.

If you are a banker, programmer, diamond merchant -or, have a job or profession where measuring length is not a requirement, there is no reason why you should be expected to know how to use measuring tapes or folding rulers. So, relax and don’t even think about feeling inadequate about it (in case you were thinking that).  

For us guys, sometimes the testosterone levels fool us into thinking we ought to know certain things we haven’t had any reason to know.

We all do what we do, don’t we?  Some people are not familiar with hand tools of any sort.  Some people are unfamiliar with debugging a computer or keeping financial records. The jewelers amoung us are skilled at measuring grams of weight and carats with special tools and equipment. Cooks measure liquids by the cupful and some other things by the spoonful.  

I don’t know anything about those things.  But, I can use my tape measure with the best of them. We are all skilled at something.

If you have a mind to do some home maintenance, improvements or repairs yourself, you need to have some knowledge of how to use a ruler to accurately measure length to the 16th of an inch.  


Let’s get into it, shall we?

I suggest you grab a cup of coffee or your favorite adult beverage and sit still for a few minutes with your ruler in hand while you read this.  You might want to bookmark this page, as well, in case you have a question later.

The typical folding ruler or measuring tape (for simplicity I’ll just say ruler) is divided into feet (in the U.S.), which are then further divided into inches, and then fractions of inches.

Rulers and tape measures come in different lengths -the typical folding rulers are 6 feet.  Less common, but available are the 8 foot folding rules. Measuring tapes start in shorter lengths -6 feet and are available in increments up to 100 feet. A good 25 footer will serve you well around the house.

The shorter tapes are 1/2″ wide. The longer tapes are available in 3/4″ or 1″ widths. I like the 1″ tapes, as they are stiffer, allowing you to reach out further with the end of it without it collapsing.

To correctly measure the length of a room, for example, you would note the length in number of ‘feet’ and the number of inches beyond the last ‘full’ foot.

Example: 10 feet, 6 inches. Another way to write that would be: 10′- 6″ or 10 ft, 6 in.

Fractions of an inch on a ruler are How to Read a Rulerdivided into sixteenths (16ths). There are 16 increments between each inch marker on the ruler.

Other incremental marks are eighths (8ths), quarters or, fourths (4ths) and the half (1/2) inch increment is in the center between the one inch increments.

Each incremental line of different value (1/16, 1/8, 1/4) is a different length, the shortest being the 16ths. Until you have practice at it, there is nothing stopping you from counting the lines if it is slightly confusing. There are, of course, 16 of them between the one inch increments.

The next shortest line is the 8th inch increment. You will find ______ of them. (If you said ‘8’ you are absolutely right)  :-)

Common Fractions – Just Like Pocket Change

It is probably a good time to revisit the terms of a common fraction. The top number (above the line is called a numerator. The bottom number is the denominator. The top number (numerator) indicates how many of the bottom number (denominator) is being referenced. (3/4 denotes that 3 of the four quarters are being referenced).

Getting back to the marks on the ruler, there are four ‘quarter inch’ marks. To clarify that, the second 1/4″ mark is denoted by the 1/2″ line because, as we know, two quarters make a half (just like pocket change). So, if the room is longer than 10 ft – 6 in. by a half inch, we would say 10′ – 6-1/2″. To say 10′ – 6-2/4″ is not technically incorrect, but it is not typically stated that way.

Same with eighths and sixteenths. The measurement is called out in the lowest denominations. So, you wouldn’t say 10 feet, 6 and 6/8 inches. How to Read a RulerThat 6/8 number can be reduced by dividing the six (numerator) and the 8 (denominator) in half.

The result is 10 ft., 6-3/4 in.  (10 feet, 6 and 3/4 inches).

Same goes with 16ths of an inch. Only the odd numbers of 16ths are spoken. For example, 10 ft, 6 and 8/16 inches, again, is not technically incorrect. The correct way to say it, though, is found by dividing the 8 and the 16 in half to come up with 10′-6-1/2″.

If the measurement was 1/16″ longer than that, the sixteenth of an inch increment would be spoken thus: 10′-6-9/16″.

The red numerals in the picture on the right are the number of inches beyond the first foot.  Fourteen inches could be stated as 1 ft.-2 inches; fifteen inches could be stated as 1′-3″.  Either is correct.


Be Forewarned

If you are engaged in measuring some type of material to be cut, you will want to remember the old adage “Measure it twice and cut it once.” It might prevent you from later scratching your head and saying “I cut it twice and it’s still too short!” (That is a joke.)  :-)


Give it Some Time

As anything new in life requires a period of familiarization before we arrive at some comfort level, with practice, and as time goes on, you will learn to quickly and (more importantly) accurately measure using a ruler.  You may also discover your preference for a folding ruler over a measuring tape -or, vice versa.  There are certain instances where one is more useful than the other.  

I think it’s a good idea to have each on hand.

You will likely find yourself making errors in your measurements from time to time.  Skilled craftsmen (and women) make mistakes once in awhile.  It is usually done in haste.  Personally, I find most of my mistakes are because I don’t write down the measurement before I mark (if I’m cutting something to length for, example) the material.  

Sometimes distractions cause us to forget the measurement before we can put it into play.  Jotting it down helps.

Learning how to read a ruler to measure accurately is a two-step process if you are installing wood trim, for example.  You need to measure the space where it is to fit into.  You then need to transpose the measurement accurately onto the material (to be cut).  


Working Safely

Working Safely at home is a hot topic.  There are numerous ways  we could end up with minor or not-so-minor injuries without leaving the house.  Keep in mind that measuring tapes are made of metal and conduct electricity quite well.   Keep the end of the tape measure at least three (3) feet from exposed energized electrical parts.  

Do not stand on chairs or five gallon buckets or counter tops.  Take the time to fetch a good ladder or stool.

You have any thoughts on this or experience (good, bad or funny)? If so, why not share your experiences by commenting below.

Do you have any thoughts on this or experience (good, bad, or funny)? If so, why not share your experiences by commenting below. If you liked this, please take the time to make use of the ‘LIKE’ button or one of the other ‘social’ buttons in the left margin of the page.  

We do appreciate you stopping by. We hope this information is useful to someone.  Thank you.

For more information:

Measuring in Inches

Fractions on a Ruler

How to Use a Ruler

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