How to Read an Inch Ruler or Tape Measure

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Hi, I'm Bob welds, and this is how to read an inch measuring tape using fractions

To keep things simple, we're only going to talk about inches

Also, we're only going to talk about your typical inch Ruler or measuring tape

We won't discuss machinist rules or anything fancy like [that]. We can do that later

I'm going to ask Sparky to show you the kind of ruler that we're talking about

Remember almost all rulers and measuring tapes have marks and numbers so let's look closely at the one that we're going to use on

This measuring tape the numbers are labeled inches

Let's take a closer. Look at a single inch I'm going to zoom in to see it better if

You count the marks you'll see that there are 16

You can do an easy check count 8 marks and see if you're at the half-inch mark

Some tapes have 32 marks on the first few inches or so just be sure that you check before you start now

you might be thinking, why 16 marks?

a typical tape measure divides each inch in half and then each half

Into quarters then the quarters are halved to make eighths our tape measure divides the eighths in half to make

Sixteenths now remember some tapes may have 32 marks. We're only working with one that has sixteenths here

So to measure with the ruler or tape measure you just need to know the fraction of an inch that the mark represents

Keep in mind that the fraction should always be in simplest form let's look at an example to see what I mean

here you can see the mark at the halfway mark between one half inch and one inch this is the

3/4 of an inch that means 3/4 of an inch

I'll erase the smaller marks so you can see the quarter is easier

Now you can plainly see [3/4]

What if I had discounted all of the 12 marks up to the line could I find the answer that way let's look at that?

The fraction would be 12/16 now. This is technically the right fraction it just needs to be reduced

Now this is not true of fractions in general, but reducing fractions to their simplest form on a tape measure or ruler

Like the ones that we're looking at is easy

You can just keep dividing by two if the number on the top is even your work is not done. Keep dividing by two

Until the top is odd, and then stop here what?


You see it's always this easy with a ruler or tape measure.

Because the denominator the number on the bottom can only be two

Four, eight, or sixteen these all divide easily by two

Now let's try some practice problems

pause the video when you see Sparkies pause then write your answer down before you hit play again

Take this example

The correct answer is [one-quarter] if you said two eights or four sixteenths you are close, you just didn't reduce the fraction.

Here's one that's a little harder pause the video and figure this one out

Did you say five [eighths] great see how the numerator is odd?

Now if you said [ten] [sixteen] you need to rewind the video a little and see about reducing

Here's one that's about as hard as they come see if you can figure this one [out]

The answer is thirteen sixteenths if you see, it's on the smallest mark

You know it's sixteen you can just count the marks starting at the Halfway point with 8

9 10 11 12 13 and

Then you can count up to 16 to make sure that you've got it, right

14 15 16 since 13 is odd. We don't have to reduce

We'll do one more this one has passed the [one-inch] mark, but I'll bet you know what to do with it

The measurement is one in three [eighths] you see you tack your fraction onto the number of whole inches in the measurement

Okay, if you got those three right you understand what's going on

keep in mind when using a new tape measure that you need to know exactly how many marks each inch has

Be sure and count them before you start if it has 16 then the smallest fraction is 1/16 if it has 32

That's a little bit different, [but] I'll bet you can figure out how to use it. We just didn't talk [about] it here

That's all for now. [I'm]

Bob welds, and these are weld notes