How much information can you pack into a QR code?

When people want to put a lot of information into a QR code, 99.9% of the time, they simply have the QR code translate into a URL. Almost all QR codes in use go to a URL. Scan the QR code, and you are immediately brought into a browser with a webpage.

But QR codes can work in a much more fascinating way. QR codes can also translate directly into a simple sentence. Or even a single word.

Here’s the QR code for the word “love”

The word "love" as a QR code

It’s kinda funny to think that the shapes in a specific QR code will ALWAYS translate to the same string. It’s not like there is some central database that converts the code to some unique ID. Each square in the QR code literally decodes to something.

Thousands of years from now, the QR code for “love” will always have the same meaning. Although, I guess one could say the same thing about writing the word. You could just translate the shapes and lines from the letters of the handwritten word.

To write “love” needs only a handful of lines and shapes to write the letterforms. The QR code for “love” requires 125 tiny black squares (not including the three large registration squares in the corners). In this case, it’s more efficient to simply write “I love you” instead of drawing out 125 squares.

“Love” might not be the best example, because it’s only four letters long. What about longer pieces of text?

How much text can a QR code hold?

Technically, a QR code can hold 4,296 characters. That’s about 741 words. (The average English word is 4.79 characters. Including the space after the word, that’s 5.79. Thus, 741 words can fit into one QR code).

Imagine a book that had only QR codes. An 80,000-word novel would take 320 pages to print. Knock that down to 108 QR codes. The entire book could get printed with 108 pages instead of 320. That would be pretty funny to read a book by scanning each page. (I suppose you could just be reading an eBook at that point.) It’s funny to think of a book of solely QR codes—and it taking less pages to print than the actual text.

Is this even possible?

A popular QR code tool states, “Some older scanner apps are having problems with texts longer than about 300 chars.” from Wow. Going from 4,296 characters down to 300 is really limiting. Ok, let’s test 300 characters.

Testing the capacity of a QR code

I copied the first 290 characters from my blog post about Comic Sans, and converted that into a QR code.

290 characters packed into one QR code.

The QR code is incredibly dense and complex. I don’t think I’ve ever seen a QR code with so many squares! Will it scan? I set the code to 3.25 inches, printed it out on my inkjet (at draft setting). My phone was able to recognize the code on the print out! That QR code translates into all 290 characters!

Screenshot of the translated results:

(There’s more text below the fold in this screenshot. I’m just demonstrating that the QR code does indeed translate to regular text)

By the way, I had to scan this using a QR reader app on my iPhone. The default camera on the iPhone does some funky things when you scan a QR code. The default camera app will automatically take the translated text, plunk it into Safari’s URL field, and try to load it as a webpage. Remember how earlier I said that most QR codes are URLs. Yeah, Apple thinks ALL QR codes are URLs. If your translated text is not a URL, then Safari ends up using your text as a search term on Google.

Hmmm. I don’t exactly want to be GOOGLING my long string of text. I want to READ IT. You’d think Apple would look at the text and see there is no “https” in front of the text, so it would render the text in a different way.

Anyhow, so I use a dedicated QR reader app to read my QR code. I’m using “QR Reader for iPhone“. It’s a free app with a tiny ad at the bottom of the screen.

Since we know a QR code holding 290 characters can fit into a 3.25″ × 3.25″ space, can we fit the same 290 characters into a 3.25 × 3.25-inch space?

To get all 290 characters to fit, I had to set it to 6.4 point—really, really small text! Here’s how that looks printed on a letter-sized paper.

one QR code can hold 290 characters of text set at 6.4 point size

Normally, for body text to be legible, it’s set to something like 10 or 11 point. MAYBE 9 point sometimes. Let’s be gracious and set the text to 9 point. Setting the 290 characters to 9 points within the 3.25 × 3.25-inch square, only I only 162 characters can fit.

Thus, in this one case, the QR code is able to hold 1.79× more than the actual text. Our 320-page novel could be printed on 179 pages, with one QR code per page (and plenty of margins).

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Mike Maddaloni
2 years ago

Where I have used QR codes to store text, I certainly haven’t used it for that much!


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