The Real Reason The Tip Of Your Tape Measure Wiggles Like That

It’s the mainstay of every toolbox; a holiday stocking stuffer for a crafter of any kind; the precursor to one of those snappy bracelets that grade school kids love to thwap you with – we’re talking, of course, of the tape measure. Retractable, dependable, and always, for some reason, slightly wobbly at the end.

But why is that? You may think it’s a result of age or use, or perhaps just your bad luck in shopping. But in fact, it’s not a bug at all – it’s a feature.

“The amount the hook moves on the end of a tape rule accounts for the exact thickness of that hook,” explained Stanley – the tool company, that is, famous for the eponymous knife and other products, rather than just some guy we asked.

Take a close look at the very beginning of the tape measure, and you should notice something a little strange. Count up the tiny notches marking out the smallest subdivisions of length – millimeters for most; 16ths-of-an-inch for the US – and you likely won’t see as many as you expect.

What’s missing from the end is an amount exactly as wide as that wobbly metal hook – meaning that, when it’s flush against the tape, all the measurements are made accurate.

“But wait!” we hear you cry. “Isn’t that precisely the problem? The hook wobbles – sometimes it comes away from the tape, making all those demarcations slightly malplaced!” Well, don’t worry: this is where the ingenuity comes in.

Think about it: when would that hook be pulled away from the tape? When it’s hooked onto something, right? If the centimeters or inches started at the beginning of the hook then, then you’d end up with a slightly too-long measurement of whatever it is you’re dealing with. In that case, you want the increments to start at the end of the hook.

Enter the wobble – the genius detail masquerading as a design flaw. “If you are doing an outside measurement, the hook would be placed on the outside of the item you are measuring,” Stanley explains. “A space would be left before the edge of the tape rule blade where that hook once stood. This space would be accounted for in the exact measurement on the tape rule blade.”

Conversely, “if you are doing an inside measurement, the hook would press up against the edge of the tape rule blade,” the company points out. “The thickness of this hook is also accounted for in the exact measurement on the tape rule blade.”

In other words: the wobble in your tape measure hook? It’s not a mistake. In fact, it’s there to save you from mistakes – even those as small as one-16th of an inch.