Skip to content
PL Get a quote

How a QR code works (without the jargon)

A QR code is simply text stored as little squares. Usually that text is a website address, but it can also be a Wi-Fi network name and password, or a whole contact card with a phone number and email address. Your phone camera reads the squares and offers to open the page, join the network or save the contact.

The three large squares in the corners help your phone find the code and work out which way round it is. The rest contains data and error correction: spare information that lets the code be read even if it is a little dirty, creased or partly covered. The standard has four levels: L, M, Q and H. Denso Wave, the company that created QR codes, says M is the most commonly used level and can restore around 15% of the data, while the highest level, H, can restore around 30%.

That is the secret behind a code with a logo: the logo in the centre simply covers some of the squares, and error correction makes up for them. A code with a logo should therefore always use level H, and the logo should stay small. Try it for yourself below.

Make a QR code with your logo live

Choose what the code should do, then enter your details and pick a colour and style. The code updates straight away and really works, so you can scan it from the screen with your phone. Underneath, you can see how well it is likely to scan and exactly what is stored in it.

I have deliberately included two poor colour choices: light grey on white and white on black. See what the checker says. These are two common reasons a nicely designed code fails in a dimly lit restaurant. To download a file ready for printing with your own logo, use the full generator.

How big should a QR code be for printing?

A simple rule of thumb: the code should be at least one tenth of the scanning distance wide. A code on a business card held in your hand can be 2 cm wide; one on a poster read from across the street needs to be much larger. Set the distance or choose an example:

Two details are easily overlooked. First, the white margin: the standard requires a clear border four small squares wide around the code. A code placed right against other artwork may fail to scan. Second, the amount of data: the longer the address, the denser the code and the larger it needs to be printed. A short address on your own domain, such as yourcompany.com/menu, makes a clearer code than a long link with parameters.

Where a QR code really helps

These are the six uses clients ask me about most often. For each one, you will find what to enter in the generator, where to put the code and a real example you can scan.

If the code needs to lead to a website you do not have yet, or one you would rather not show customers, this is a good time to change that. See how I build websites and online shops.

Static or dynamic QR code? It matters more than you think

Most people do not realise there are two types of QR code. A static code stores the address in the squares themselves and leads straight to your website. A dynamic code first goes to the server of the company that generated it, which then redirects the visitor. That gives you scan statistics and lets you change the destination, but there is a catch. Use the switch below to see what happens when the subscription ends.

Some generators advertise themselves as free but create dynamic codes with a trial period. After a few days or weeks, the codes on menus and business cards you have already printed stop working until you pay for a subscription. My generator only makes static codes: what you download keeps working and does not depend on me. If you want to change the content later without reprinting, point the code to a page on your own website, such as yourcompany.com/menu, and update that page.

Fake QR codes: how to protect your customers

A QR code has one drawback: you cannot read it by eye. Scammers take advantage of this. The scam even has a name: quishing. The Polish government’s guide warns that QR codes can easily hide dangerous links. The US Federal Trade Commission (FTC) describes cases where scammers stuck their own codes over genuine ones, for example on parking meters.

For a business, that means three simple rules. Print the code directly on the menu, stand or poster rather than adding a separate sticker, which is easier to cover with another one. Put your website address beside the code, such as “yourrestaurant.com/menu”, so customers can compare it with the address their phone shows. Check your codes occasionally, especially those near the entrance or in outdoor seating areas. Avoid asking for card details through a QR code: use a familiar payment page or a card terminal.

Before sending your QR code to print

Fixing a mistake after printing a thousand flyers costs much more than five minutes of checking. Tick off each item: the checklist is saved in this browser.

Has your printer asked for a vector file? Download the code as SVG or PDF from the generator: vector artwork stays sharp even on a banner.

Sources

  1. Denso Wave (creator of QR codes): error correction levels L, M, Q, H
  2. Denso Wave: how to create QR codes size and margin
  3. ZXing: code content formats (Wi-Fi, vCard)
  4. Gov.pl: the Polish government’s guide to quishing and QR code scams 13 February 2023
  5. FTC: scammers hide harmful links in QR codes 6 December 2023
  6. Google: review links and QR codes for your business in English
  7. Google: review policies no incentives for reviews

Questions about QR codes