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What Does a Black Diamond On a Tape Measure Mean?

what are black diamonds on tape measure for

If you’ve ever spent much time around a tape measure, then you’ve probably asked yourself this exact question. I know I sure did!

Tape measures are funny things when you really take a look at them. I mean, there’s markings all of the place…black lines, black numbers, red numbers, squares and little black diamonds. I don’t remember the first time I looked at a tape measure, but I’m sure I was pretty confused as to what all that meant.

One of the most confusing things on the tape measure to me were the black diamonds. What are they for?

What Does The Black Diamond On a Tape Measure Mean?

Stanley 33-425 25-Foot by 1-Inch Measuring Tape

It wasn’t until I was an adult that I finally set out to learn what those little black diamonds the the tape measure meant. And to be totally honest, I didn’t take the time to figure out what those black diamonds meant even after I’d started making a living out of using a tape measure!

The black diamonds on a tape measure really aren’t a big mystery. As a matter of fact, I wish I’d known what they meant sooner. I could have used them!

To answer this question, I’ve checked out a number of sites, and the best explanation is from

“These are handy markings if you want to achieve equal spacing for five framing members per every 8 feet. If you decide to use 16-inch-on center spacing, you’ll end up with six framing members for every 8 feet. If you space things at 24-inch centers, you’ll have four framing members for each 8 feet. Some carpenters like to have five framing members per every 8 feet so the sheathing over the framing is less spongy and stiffer. “

A real life example of this would be laying out 5 floor trusses in preparation for a 4×8 tongue and groove sub-floor. That’s exactly what uses these black arrows for.

“The diamonds start at the 19.2 inches mark on the tape and can be utilized to help correctly space the floor trusses for a 4×8 T&G sub-floor with a span rating of 20” o.c. The black diamonds provide a visual cue to help you work faster.

Of course there is a joist or Rimboard to start the framing but after that there are 5 open bays and 5 joists for each 4×8 sub-floor panel. So if you divide 96 inches (8 feet) by 5 (open bays), you get the required 19.2”o.c. for the 20”o.c. span rating on the sub-floor.”

Final Thoughts

So that’s the deal behind the black diamonds on tape measures. To be honest, for how hand of a tool these particular markings are, it’s surprising how many people aren’t aware of what they’re actually for. I know there’s times where I could have definitely used them to make my work faster.

How about you? Now that you know what the diamonds are for, will you be able to utilize them?


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