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QR Codes: Why is A Square Missing At The Bottom Right Corner?

Why is the square at bottom right is missing in QR codes?

This post is a part of our Crazy Google Searches series.

QR codes have become a part of our lives. We scan QR codes for making payments, identification, visiting websites etc. It's easy to scan a code and consume the crucial info, rather than searching (or entering) the info manually.

If you keenly notice a QR code, you could have seen it has big squares in the below corners:

  1. Top left

  2. Top right

  3. Bottom left

But what about the bottom right corner? Well, this blog post is to tell you why the bottom right corner of a QR code doesn't have the big square.

Before we break the ice, we'd like to give you a clue and help you find out the answer yourself.

Imagine if there's a square at the fourth corner also. Now how will the QR scanner understand which is the top side of the QR code?

You got it right. The absent square helps the scanner determine the correct position of the QR code.

But the interesting thing is.. Technically a square is present near the bottom right corner to signal the QR code scanner that it's the bottom right side of the QR code.

This square at the bottom right is comparatively smaller than the squares at the 3 other corners.

So even if you keep the QR code upside down and scan it, the QR code scanner will determine the bottom right corner with the presence of this smaller square (as highlighted in the image below).

The small square at bottom right helps the scanner to identify the QR code's position

Once the scanner finds this small square at the bottom right, it can easily determine the actual position of the QR code even if it is tilted or kept upside down (or scanned from a tilted position or upside down position).

QR codes have many other interesting components to pamper our curiosity. But the one question that runs on top of our minds is how all QR codes are unique when a ton of online QR code generator tools are available?

How these tools work together (in some way) to ensure they don't generate a duplicate QR code?

While we're Googling to find the answer to this question, please share the answer (if you already know it) on the comments section :-)


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