How To Read a Tape Measure for Designing a Room

Have you heard the phrase, “Measure twice, cut once”? If you’ve ever had the “fun challenge” of a first woodworking project, you may have learned this lesson the hard way. 

During a hectic home design project, the thousands of little tick marks on the tape measure can run together and bring back algebra nightmares. DIY projects are the most empowering way to own your space, so it’s worth learning how to use your measuring tools.

Let’s demystify the tape measure together, so you never have to call your dad for help measuring materials again.

‍Components of a Tape Measure

There are lots of different options when it comes to tape measures. The best tape measure, however, is the one you have on you and that you know how to use for precise measurements. 

Rubber or Metal Casing 

Metal tape measures were invented by the hoop skirt designers of the 18th century, but many new forms have been developed since then.

All-metal tape measures can be heavy, which you may find helpful when needing a counterweight to keep the tape from bending. A lighter material, like rubber, is easier to carry around and may not chip tile if you drop it on the floor — just something to consider. 

Each case has its own exact measurement printed on the outside. You may need to add this number to your calculations when measuring the inside of a cabinet where you use the case itself as part of the measurement. It’s an easy way to get a read on a corner.

Metal Hook

The metal hook, or tang, at the end of the tape grabs the surface you’re measuring, like the edge of a table. The tang allows you to walk away, extending the measuring tape to the far edge for an accurate reading with no additional help holding it in place: Very useful when taking measurements alone. 

That wobbly itty-bitty piece of metal is a design marvel, perhaps more so than Tang, the drink of choice of NASA’s 1960s astronaut lineup. It is exactly 1/16 of an inch so that when the hook sits inside of an area to be measured, like a shelf, it becomes part of your measurement and is zero — no need to add length.

However, if you use the hook to grab the edge of a wall, as you pull the tape measure, the tang extends 1/16 of an inch from the end of your tape. The extra length compensates for its being on the outside of the wall or outside of your measurement. 

Nail Grab

The tiny hole at the end of the tang, also called a nail grab, makes it easy to keep the end of your measuring tape stationary while measuring something large. You can tap a nail into the edge of your piece of wood, hook the nail grab and let the tape measure extend from there. 

Scribing Tool/Scriber

The metal hook often has a serrated edge that you can use as a scribing tool. Press it into your wood for an accurate measurement when you don’t have a pencil handy. 

Retractable Tape Measure

The retractable tape measure is indispensable for the home designer. Unlike tailor’s tape, a retractable measuring tape coils itself up when you are finished working and extends with a little tug.

The rigid measuring surface, called the blade, is concave in the center, allowing it to stay firm while you measure. Again, super handy when you are DIY-ing by yourself.

Thumb Lock 

The thumb lock on top of the retractable tape measure stops the tape from extending or retracting on its own. It’s a must when working alone, and why wouldn’t you be working alone? You can do this! 

Lefty Righty Measuring Tape

This home-planning gadget has the correct measurements written on both edges of the blade. Whether you’re pulling the hook with your left or right hand, there will always be a measurement written right side up for you to read. 

Belt Clip

A belt clip isn’t necessary, but if you are juggling tape measure, pencil, and paper, you may appreciate having the ability to hang your tool on the top of your pocket. 

Imperial Units or Metric Units

Let’s get past the most fear-inducing part of the measuring process. Whether you’re working with Imperial or metric units, figuring out fractional marks is not rocket science. 

Imperial Tape Measure Markings

If you are in the U.S., you may be most comfortable with Imperial (even though we all know it’s actually more complicated). Our main unit of measure is the inch. All of the fractions of an inch are represented by hash marks of varying lengths. 

• The inch marks are the longest lines on the blade; they proceed from the tang and increase by one with each successive mark.

• The one-half-inch mark, the next longest hash mark, divides each inch into two equal halves. There is only one of these per inch.

• The quarter-inch mark is the third longest marking, dividing the inch into four equal parts. There are two of these per inch, dividing each half into two equal parts. 

• The eighth-inch mark further divides each quarter into two equal parts, for a total of eight parts per inch mark. 

• The sixteenth-inch mark (You see where this is going.) is the shortest of all the hash marks on the tape measure. There are eight of them, dividing each eighth-inch in half, for a total of 16 equal parts per inch.

• The footmark comes every 12 inches and usually announces itself with a bold print or an arrow. 

Let’s Use Imperial Measurements

If you’re measuring a dining table and the table extends three-sixteenths of an inch beyond 7ft 1in, then your final measurement is 7ft 1 3/16in. You don’t have to bother keeping track of the fractions of an inch: There are tape measures that have every single hash mark clearly labeled as a fraction. 

Metric Tape Measure 

The metric side of a tape measure looks far less busy than its counterpart. It’s broken up into numbered measurements by tenths. This makes converting from smaller units of measurement to larger no-nonsense.

• The millimeter is the smallest marking on your tape measure. It is equal to 1/10 of a centimeter. 

• A centimeter is made up of ten millimeters. These are the black numbers you see on your metric tape measure. Converting millimeters to centimeters requires moving the decimal point of your number over one space to the left. (1 mm = 0.1cm)

• The meter is comprised of 100 centimeters and is usually marked in bold red on the blade. Converting centimeters to meters requires moving your decimal two spaces to the left. (200cm = 2.00 m)

You don’t even have to bother with unit conversion while you measure. Just record your measurement to the nearest centimeter and millimeter. You can do the math later. 

Now Let’s Try Metric

Let’s put your beautiful mind to the test and measure something in metric units. If we stretch our tape measure across the same rug and it is 9 millimeters past the 216-centimeter mark, jot down 216cm, 9mm. You have a rug that is 216.9 cm or 2.169 m.

Bells and Whistles

There are a few more added benefits to using the Imperial side of a standard tape measure. They’re particularly helpful if you are building and want to assess lumber needs and stud or I-Beam placement.

The Stud Mark 

The stud marking on your measure is every 16 inches and is indicated by your inch mark printed in bold red. This makes planning where you will hang things or how many studs you need across a space much easier. 

The Black Diamonds 

Like the stud mark, the black diamond (sometimes a triangle) marks every 19 3/16 inches. It indicates how to space I-Beam Timbers if you are getting serious about your remodel and want to know exactly where to place engineered timbers rather than traditional floor joists.

How To Avoid Common Measuring Mistakes

Now that you’ve conquered tape measure math, keep these tips in mind to avoid common measurement errors:

Don’t Let It Sag

When stretching your tape measure along something, don’t let it pull away from the object or sag. Even the slightest curve in your blade can greatly affect the overall length recorded.

Round Up, Not Down 

Even with all those tiny tic marks, you may find that what you are measuring ends right between two markings. Play it safe and round up numbers rather than rounding down. It is much easier to shave a little off a piece of wood than to find it too small and start over. 

Mark With a “V”

“V” isn’t only for Vendetta; it’s also for very careful home design planning. 

When you locate the exact place that you need to mark a measurement with your pencil, try making a “V,” with the point being the correct place of measurement. A hastily drawn slash mark tends to slant and make your results unclear.

That’s everything you need to know to tackle measuring your home design correctly. You now know what every carpenter does about measuring surfaces, so don’t forget to plan your space without this tool. 

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^Sources:

^{America Has Been Struggling With the Metric System | Smithsonian Magazine}

^{How Hoop Skirts Led to Tape Measures | Smithsonian Magazine}

^{10 Most Essential Tools for A Craftsman to Have | CCR-Mag.com}