QR Code Error Correction: How Does it Work?

Update:  April 26, 2024

The QR code error correction is a unique feature that allows printed QR codes to withstand damage like scratches and smudging yet still work just fine.

This means they can still redirect scanners to the embedded data even though external factors have affected the state of the QR code image.

On top of that, this feature also further improves the readability of QR codes: You can still scan them even though objects like stickers partially cover the QR code.

This unique feature—paired with their impressive abilities and versatile functions—make QR codes a truly reliable solution for every industry.

It may sound complicated, but we’re here to help you.

This article will guide you on how this works, and we’ll also show you how to create your QR code with the best QR code generator.

What is a QR code?

A Quick Response or QR code is a two-dimensional matrix barcode comprising black boxes and white spaces forming a square pattern, and it can store huge amounts of binary data.

Each black box or module represents a one, while the white space represents a zero.

But unlike the barcode, it has a much bigger storage capacity.

The QR code can store numbers, letters, or a combination of both; the best example being the URL.

But with today’s advanced tech, QR codes can now store digital business cards, files, and more.

Users must scan the QR code with their smartphone camera or a QR code scanner app to access the encoded data. They will then see the information on their screens.

Related: How Do QR Codes Work? We've Got All Your Questions Covered

How does the QR error correction feature work?

QR code error correction feature

The QR code correction level guarantees that users who scan your QR code can still retrieve or access its embedded data even when damaged.

This is possible with the Reed-Solomon error-correction algorithm: a clever system that can fix possible mistakes or errors in the transmission or storage of data. It got its name from its developers: Irving Reed and Gustave Solomon.

The algorithm then adds extra modules to the QR code’s pattern, which contain duplicates of your embedded data.

Scanners can still recognize your QR code through these additional modules, even if a part is damaged, missing, or covered.

As a result, your printed QR code lasts longer despite external factors.

The different QR code error correction levels

The error correction in QR codes comes in four levels, each capable of withstanding a different maximum amount of damage. 

And since the error correction works by adding extra modules, the QR code’s dimensions will increase as its error correction level rises.

An online QR code generator with error correction platforms offers different QR code correction level of functionality, so it’s important to go for one that provides the level that suits your needs. Here are the four levels:

Level L (Low)

This is the lowest error correction level suitable for generating a QR code image with a less cluttered-looking pattern.

It’s suitable when the QR code is expected to endure minimal damage. It offers an error correction rate of approximately 7%.

For instance, you can use Level L QR codes for personal purposes, such as sharing contact information or directing users to your website.


Level M (Medium)

The medium error correction level strikes a balance between error correction capability and the size of the QR code.

It’s suitable for most general purposes like marketing and can handle moderate damage.

M-level QR codes can recover up to 15% of the data if errors occur.

Level Q (Quartile)

The quartile error correction level is handy when the QR code might face more significant damage or distortion.

Q-level QR codes can recover up to 25% of the data in case of errors or damage.

Logistics, healthcare, or event management can benefit from Level Q QR codes to maintain data integrity, even in demanding environments.

Level H (High)

The high error correction level offers the maximum amount of error correction. It’s used when the QR code risks severe damage or distortion.

A QR code with Level H error correction can recover up to 30% of its data.

Industries like manufacturing and construction can use Level H QR codes to ensure information remains accessible, even in harsh or high-risk conditions.

How to determine the error correction level of a QR code

You can quickly determine the error correction level of a QR code. No tools, devices, or apps are needed; you’ll need only your eyes.

Simply examine the QR code’s appearance and find the error correction symbol, a pair of boxes stacked vertically near the eye on the bottom left of your QR code’s pattern.

Quick note: The QR code’s eyes or the position detection patterns are the three squares you find at the bottom left, top left, and top right corners of your QR code.

These help scanners identify the orientation of the code. Through these squares, smartphones can scan the QR code from any angle.

Now that you know where to find it, it’s time you learn the legend to help you quickly identify the code’s error correction level. Follow this guide:

  • Level L: Both boxes are shaded
  • Level M: Only the bottom box is shaded
  • Level Q: Only the top box is shaded
  • Level H: Both boxes are clear; you’ll only see a blank space

Do higher QR error correction levels lead to slower scans?

The error correction adds extra squares onto the QR code’s pattern to store the duplicate data, meaning higher levels lead to bigger QR codes with denser patterns.

And the thing with QR codes is that the more congested their patterns are, the more time it takes to scan them. 

But here’s the truth: It does not necessarily result in slower scanning.

The scanning speed primarily depends on the capabilities of the scanning device or application.

Modern scanning technologies have advanced significantly, letting them efficiently process larger QR codes with higher error correction levels.

Therefore, the impact on scanning speed between error correction levels is often minimal or none at all.

You can go for higher QR code correction level of errors without worrying about the scan speed.

How a high error correction level affects dynamic QR codes

There are two QR code types: Static, the ones that are permanent once generated, and dynamic, the editable ones that come with advanced features like scan tracking.

A dynamic QR code stores a short URL in its pattern, leading to your embedded data. Since it’s not hard-coded, you can edit or replace it anytime.

After doing so, the QR code will redirect to another data, yet it still stores the same short URL.

This unique feature guarantees that the dynamic QR code’s pattern will not become too crowded even with a high error correction level.

This way, your QR code has more data security while maintaining a more optimal-looking, less dense pattern.

This is only one of the many reasons why many brands and businesses use a dynamic QR code generator with error correction for their campaigns.

Benefits of examining the error correction level of your QR codes

Enhanced scanning reliability

Error correction guarantees that your QR code will remain scannable by providing better damage resistance. Users can still scan your QR code despite scratches or smudges.

This unique feature also increases scanning speed since the scanner can still recognize the QR code despite partial obstructions or minor alterations to the image.

Assessing damage resistance

The QR error correction feature allows companies to choose the appropriate level for their QR code, depending on their intended purpose.

For instance, QR codes on posters on streets and outdoor places may need higher correction levels than those printed on product packaging.

This helps businesses guarantee that their QR codes will last long, saving resources.

Improved data integrity

Opting for higher error correction levels equips your codes with robust detection and correction capabilities, reducing the chances of data corruption during scanning or transmission. 

This is handy when handling sensitive information like payment details or personal data that demands utmost security and accuracy.


Cost-efficient

Imagine creating a new set of printed QR codes because the first ones you made and deployed no longer work due to damage. That’s a pricey inconvenience.

But with the error correction feature, you can have more durable and long-lasting QR codes that will still be readable despite the damage.

This reduces the need for reprinting QR codes, saving you effort and money.

Saves the environment

And since you won’t print or reprint as many QR codes as before with the error correction, you can reduce paper usage and waste.

This is a small yet meaningful move in saving the environment.

Create your QR code now with QR TIGER: the most advanced QR code generator 

Looking for high QR code correction levels? QR TIGER is your best choice. It offers the highest QR code error correction on all its QR codes, whether static or dynamic.

This reliable and advanced software has a user-friendly interface and offers many features like customization, tracking, software integrations, and more.

And on top of that, renowned brands like Cartier, Vaynermedia, and Hilton trust this ISO 27001-certified and GDPR-compliant QR code software.

Go to the best QR code generator and sign up for a freemium account today.

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