Why Are Tape Measures Curved Instead Of Flat?

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For such a seemingly simple tool, there's a lot of mystery wrapped up in your compact tape measure. The reasoning behind their hidden abilities and unique design characteristics continues to intrigue tool aficionados while simultaneously giving them greater appreciation for what went into the construction of their handy little tool. Among the details that continue to perplex longtime tape measure users — such as their loose ends and black diamonds — is the reason for the blade sporting a curved design. 

When you look straight down at tape measures commonly used for construction and hobbyists, you'll notice that the edge has a distinct curve to it that causes a dip in the center of the entire blade. At first, it may appear counterintuitive. Why would a tool used so commonly for measuring straight lines and angles not be flat? Wouldn't that be more accurate? In reality, a curved tape measure is just as reliable as any other quality measuring tool, as long as you're making the most out of the tape and its features. 

The real reason tape measures are often curved is a matter of rigidity. When you need to extend the blade especially far, the curved design allows it to maintain its shape and not bend undesirably. This allows you to ensure more accurate measurements, especially in situations where you're the only person holding the measure.

Curved tape measures are the standard for a reason. In terms of strength, stability, and versatility, they certainly have the edge. But of course, they're far from the only tape measure on the market. Flat tape measures are not hard to come by, as many highly-rated options exist from well-known brands, such as Stanley PowerLock Key Tape. But does that make them the better overall pick?

Flat tape measures certainly have their uses. Oftentimes, these tools are far slimmer than their curved counterparts, making them nearly effortless to throw in your pocket and carry around throughout the day. These capabilities also make it great for taking quick measurements for smaller-scale tasks, especially if you need something that requires less effort to help draw out a straight line. Certain models even come with surprising features, such as the FastCap Flatback Story Pole, which possesses an integrated pencil sharpener and an erasable notepad fixed onto its base. 

Despite these perks, it's hard to say that these beat out curved tape measures. Flat blade models suffer from weak blades that struggle to maintain their stability when extended. YouTuber Silver Cymbal's Stanley tape measure was not even able to get to two feet without bending. Additionally, some lack the important accuracy features of more traditional models, such as the wiggling metallic tab at the end, with some flat models opting for a stationary tab.