QR codes vs. Barcodes

All Ages
Computer Science

Which contains more information: a QR code, or a barcode? Grab a ruler and find out!

Required Materials

  • A basic printer to print some black and white PDF files
  • A ruler (metric or standard)
  • A device to scan QR codes and barcodes, such as:

Printable Materials

Important information

Another name for a bar code is a UPC code The UPC stands for stands for Universal Product Code

The QR in “QR code” stands for Quick Response

On a barcode, one group of numbers indicates which company produced the product while another group of numbers indicates the specific product out of that company’s lineup of products is being sold. Look up the UPC of each barcode on https://www.upcitemdb.com or https://www.upcindex.com and note the company that sells that cereal. Then look closely at the barcodes. See if you can figure out which group of numbers describes the company!

There are different sizes of QR codes. If you look closely at the printable pdf of example QR codes above you will notice that the black and white squares are larger for some QR codes and smaller for other QR codes. Look at the printable pdf of example QR codes to see different sizes of QR codes.

Consider the smallest QR code (which would have the largest black and white squares). Does the smallest QR code contain more information than a bar code?

What are the limitations of barcodes? How many different companies can it include? What is the max number of products that a company can sell? Which limitation do you think might pose a bigger problem as more companies are created and more products are developed?

How much of the QR code can you cover before the camera app fails to extract the link? Can you cover part of the bar code and still have the camera app extract the correct UPC code?

Optional: use a black marker to fill in some of the white squares of the QR code. Does it change the link? Use the marker to fill in some of the white lines on the bar code. What happens?

Advanced questions

Standard barcodes have a series of vertical lines that are either black or white. If you used those lines to create an unsigned binary number system (similar to this video from 3blue1brown but with more than five fingers or more than two hands) then how high could you count? How does this compare to the ten digit code below the lines and how high that number could ever go? Which is larger? Which is smaller? What does this tell you about the design of a barcode and how might you have designed it differently?

Check out this youtube video about How Barcodes work. Describe qualitatively in your own words why the extra numbers at the beginning and the end of the barcode are important. Do these numbers help to specify the product or are they there for some other purpose?

Why can you cover part of the QR code and still get the link from scanning the QR code with the camera app? Shouldn’t the link be corrupted by blocking part of the message?