The Tool That’s Made To Be Broken

If you have a tape measure handy, go grab it. Don’t worry, this email will still be here when you get back. And if you don’t have one handy, no big deal, I’ll explain anyway, and you can try it later if you want. Either way, there’s a good chance you’re using it wrong.

With your tape measure in hand, go and measure something — it really doesn’t matter what. Grab the metal hook and pull out the tape measure, and  — did you notice that the hook is a little loose? If so, did you compensate for the that? Maybe you started your measurement at the 1” mark instead of at the end, and then just subtracted your extra inch afterward. Or maybe you just tightened the hook?

Well, if you did, the first thing, that’s fine — but probably unnecessary. If you tightened the hook, well, you shouldn’t have. The hook is intentionally loose.

To understand why, you need to realize that there are two ways to use a tape measure to, well, measure something. The first way is to place the hook against the inside part of a wall. The wall pushes the head of the hook against the tape, as seen below (via StackOverflow). As a result, the distance you’re measuring is equal to the thickness of the hook’s head plus the length of the extended tape.


But there’s another way to use the hook — as a hook. (Makes sense.) In that case, you’d anchor the back of the hook’s head on the outside of the edge of whatever you’re trying to measure; for example, if you lay the tape on a table, the hook will hang tightly over the side. And… that’s a problem, as in that case, the width of the head isn’t included in the distance being measured. Or, it wouldn’t be, if the head of the hook weren’t loose.

But thankfully, the hook is able to account for this problem. Here’s another picture, this time with the tab extended (again via StackOverflow):


See that little gap between the back of the hook’s head and the start of the tape measure? It’s caused by the fact that the hook head is loose. On a properly calibrated tape measure, the span of that gap will be equal to the width of the hook. And as a result, regardless of which method you use, the result will be equal.

So please, don’t “fix” your tape measure. It’s supposed to be like that.

Bonus fact: The metal hook has a name — it’s called a tang.

From the Archives: Putting It Together Again: It’s about Humpty Dumpty, which really has nothing to do with this article, but Humpty Dumpty is broken and the tape measure isn’t, which was the connection I made. Okay, that doesn’t make any sense, but that’s fine; it’s a good article, you’ll enjoy it.

Take the Quiz: Can you name the missing tool or hardware from names, titles, and phrases?

Related: A keychain tape measure. About $5 and change, 4.8 stars on over 100 reviews. Because you’ll never know when you’ll need to measure something.