QR codes and the error correction level

QR codes support four levels of error correction to enable recovery of missing, misread, or obscured data. Greater redundancy is achieved at the cost of being able to store less data.

These levels are referred to by letter;

• L - Allows recovery of up to 7% data loss
• M - Allows recovery of up to 15% data loss
• Q - Allows recovery of up to 25% data loss
• H - Allows recovery of up to 30% data loss

In practical use, lower error levels generate simpler codes, which means that they can be printed smaller and still resolved by cellphone camera optics.

Higher error error levels can suffer more damage, but must be printed larger to make that denser pattern scannable.

Choosing the right Error Correction Level

What level you use depends on your needs.

Smaller printing generally demands a less-complex QR code, so a lower level is better.

If your QR code is likely to suffer damage, on the outside of a shipping container or in a high-traffic location, consider a higher error level.

Important Note for Graphics Designers

Graphics designers can use Error Level effectively based on design goals.

If you want to manually adjust the path of the code, to create interesting corner effects, etc. you might consider a simpler code to lessen your work.

If you intend to obscure or delete part of the code, than a higher error level will make the code able to withstand larger amounts of damage.