Everything You Ever Wanted to Know About Barcodes

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Podcast Transcript

In 1949, a young inventor by the name of Norman Woodland was sitting on the beach in Florida. While drawing some lines in the sand, he had an idea that would revolutionize the world of retail and logistics.

In fact, his invention might be found somewhere around you or on your person at this moment.

Learn more about bar codes, and the closely related Universal Product Codes, on this episode of Everything Everywhere Daily.

Unless you’ve actually been involved with inventory, at any part of the inventory chain, you might not realize just how insanely complicated managing tens of thousands of items can be. 

Just to put it into perspective, the average supermarket in the United States has anywhere from 15,000 to 60,000 different products for sale. By this, I don’t mean individual items, but products. So 20 boxes of Lucky Charms count as one product. 

For the longest time, going well into the 20th century, managing all these products was done by hand and on paper. It was slow and error-prone. 

There was a great need for a system that could automate read and manage inventory.

The story of the modern barcode actually began way back in 1948. 

A student at Drexel University in Philadelphia named Bernard Silver overheard the president of a chain of grocery stores talking to one of the deans at the college about developing a system to read product information at checkout. 

Silver told his friend Norman Woodland about the problem and they began trying to come up with a solution. 

This was still in the days before computers were ubiquitous, so many of their solutions really didn’t work.

Woodland left Drexel but didn’t give up on the project, He moved to Miami Beach to live in an apartment owned by his grandfather when he came up with the idea while drawing lines in the sand. 

As he described it, “I remember I was thinking about dots and dashes when I poked my four fingers into the sand and, for whatever reason—I didn’t know—I pulled my hand toward me and I had four lines. I said ‘Golly! Now I have four lines and they could be wide lines and narrow lines, instead of dots and dashes. Now I have a better chance of finding the doggone thing.’ Then, only seconds later, I took my four fingers—they were still in the sand—and I swept them round into a circle.”

The first iteration of it was a circle and it looked like the rings on a tree. The reason for this is that it could then be read in any direction. More on that in a bit. 

They built a crude system with a 500-watt incandescent lightbulb and an oscilloscope. 

They kind of sort of got it to work, but the truth was it was an idea far ahead of its time. The fact that they came up with this idea before computers were widespread and lasers were invented, is actually really impressive.

They were awarded a patent in 1952, but little was done with the idea. 

It would be another 20 years before the idea of using barcodes really took off. The idea was waiting for technology to catch up with it. 

RCA purchased the original patents but was unable to create a marketable product. They did end up creating a prototype system in 1972 which was actually tested in a Kroger foods in Cincinnati, but the hardest part they found was actually printing the circular labels. 

The barcodes we know today first took form when the National Association of Food Chains created the Ad-Hoc Committee for U.S. Supermarkets on a Uniform Grocery-Product Code. They created the standards for the Uniform Product Codes or UPC. These are the numbers which you can find on almost every product in the world today.

The creation of these codes was a huge undertaking. Every industry had its own concerns and its own way of doing things. 

In 1973, the committee adopted a proposal by IBM for both the numbering and the way the bar codes would be printed, allowing the codes to be read even if there was a printing error. Coincidently, on the IBM team was none other than Norman Woodland, the guy who first came up with the idea back in 1949. However, the IBM rectangular system was not the same as his circular system. 

On June 26, 1974, the very first purchase using a UPC code and a barcode scanner was conducted at Marsh’s Supermarket in Troy, Ohio. The purchase was a 10-pack of Wrigley’s Juicy Fruit gum. Both the gum and the receipt are on display at the Smithsonian Institute.

While the technology existed in 1974, it would still be a while before it went into popular use. There was a huge chicken and egg problem. While UPC codes could bring cost savings to supermarkets, it was calculated that at least 70% of the items in a supermarket had to be using the UPC codes before it made sense to invest in the equipment. 

That means that the industry had to adopt the codes before scanners would begin being seen at cash registers. 

Adoption of barcodes really began to take off in the early 1980s when big retail chains like K-Mart and Sears starting using them. 

As more grocery stores began using bar codes, they found immediate success. Not only did they experience a 1-2% decrease in operating costs, not a small amount which your margins are only 1-2% to begin with, but the stores which adopted it also saw an increase in sales. Sales at most stores would increase slowly and top out at 10-12% above what they were before barcode scanning, and the sales stayed there. 

When these mysterious codes started appearing on products, conspiracy theories sprang up to explain them. Perhaps the biggest one was that the barcodes were the mark of the beast from the bible. That embedded in the barcode was the number 666.

Spoiler: 666 is not embedded in barcodes, and I think I’ll have to do a future episode on the number of the beast.

I should note, that barcodes in general are not exclusive to reading UPC codes, even if they are the most common form of barcodes. Barcodes can be used for a wide variety of things that are not UPC codes. FedEx has its own system that uses barcodes, and custom barcodes can be used to track everything from cargo containers to patients in a hospital.

Back in the year 2000, there was a company called CueCat that created a system where newspapers could put a barcode in an article, and then readers could scan it at home to go to a website. To make this a thing, they sent out free Cuecat barcode scanners to anyone who wanted one. 

Of course, people figured out immediately that you could scan anything with these, and some people, like myself, got a free CueCat scanner and used it to catalog all of their stuff. 

Now, the history of the barcode is interesting, but what exactly is in a barcode? Here, I’ll go into the weeds to explain exactly why a UPC code is the way it is. 

If you happen to have a UPC code next to you, take it out to look at it. If you have a can or bottle of a soft drink they will usually have one, as will most packaged products. 

A UPC code consists of 12 numbers. There are no other characters or letters in the code. It is just a string of 12 numbers. 

11 of the numbers can be used to identify a company and a product. So in theory, there is a maximum of 100 billion unique UPC codes which can be created. 

Any company that wants to create their own unique UPC code can apply to get one. 

The first six to nine digits are the company identifier. As there is a fixed number of digits, the smaller the company number, the more room there is for products. That is why it costs more for a lower company number, and it is usually reserved for large companies that manufacture a large number of products. 

The remaining numbers are for products and they are assigned by the company. 

There are 95 unique bar spaces in a UPC barcode. This might surprise you because it doesn’t seem like there are 95 lines. That is because the thick and thin black and white lines might be 3 or 4 of the lines together. 

The black and white lines are binary. Black lines are 1’s and white lines are 0’s. 

At the bottom of the code, you will see 12 digits. There is 1 digit by itself, on the left, then some longer lines, then 5 digits, then some longer lines in the middle, then 5 more digits, then longer lines, and then finally 1 digit by itself on the far right. 

The 95 lines are grouped into 15 sections. 

Three of the groups are called guards, They are the longer lines in the far left, far right, and in the middle. The length of these lines isn’t really relevant, other than for formatting and separating the numbers. 

The guard lines tell the scanner where the boundaries of the barcode are. The right and left guard are both three digits each, and the middle guard is 5 digits. 

The remaining 12 sections represent the UPC numbers. There are six numbers on the right and six numbers on the left. 

Left numbers always start with a 0, and numbers on the right always start with a 1. This is how a scanner can still read a barcode if it is upside down. If the numbers on the left all start with a 1, then the scanner knows the code is upside down, and it reverses it. 

For those of you knowledgeable in computers, note that each number uses 7 bits, not the normal 8 bits that characters use in ASCII. 

The reason why 11 digits are used for company and product identification, is because the rightmost number, the 12th digit, is used as a checksum. A computer can quickly run a calculation on the 11 numbers it read and check that against the 12th number.

If the number doesn’t check, then it has to scan the code again. 

The leftmost number is store categories. 0 is for a standard barcode, 2 is for items that have to be weighed like fruit, 3 is for items from a pharmacy, and 5 is for coupons. 

What I just described is the most common UPC-A code. There are other variations such as UPC-E codes. There is also another system called the International Article Number or European Article Number.

Before I end, I should note that everything I’ve talked about so far are called one-dimensional barcodes. They can be read in a line at any point along the code, even diagonal. 

However, because they are one-dimensional, the amount of data they can encode is limited. 

There are now two-dimensional barcodes that you are probably familiar with. The most popular one is QR codes. 

QR codes can encode far more information than a regular one-dimensional bar code. A QR code can encode up to 4,296 characters, including letters, numbers, and punctuation, or it can encode 7,089 digits if you only encoded numbers. 

That is why you have to use something like a QR code for sharing a website URL, not a simple barcode. 

One last thing I should also note is that there is no information in a UPC barcode about the product itself. It is just an ID number and nothing more. All of the information about the product, such as price, would be located in a database and it would then be associated with the ID number. 

Barcodes are incredibly ubiquitous in the world today. It is estimated that every day, there are 500 billion barcodes scanned around the world. Without the simple barcode, much of our modern economy simply wouldn’t function. 


The associate producer of Everything Everywhere Daily is Thor Thomsen. 

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