Feature
QR Error Correction Level: Choose L, M, Q, or H.
Select the right QR error correction level: L for clean digital displays, M for general business, Q for print/signage, H for logo-embedded codes.
What Is Error Correction in a QR Code?
Every QR code uses Reed-Solomon error correction, a mathematical algorithm that embeds redundant data into the code. This redundancy lets scanners recover the original data even if part of the code is obscured, dirty, or damaged. SMLLR lets Pro and above users choose the correction level that fits their medium — so your code stays scannable in every real-world environment.
- L (Low) — ~7% recovery capacity: clean digital screens, email campaigns, websites
- M (Medium) — ~15% recovery: general-purpose business cards, packaging
- Q (Quartile) — ~25% recovery: printed materials, outdoor signage, banners (default)
- H (High) — ~30% recovery: logo-embedded codes, industrial labels, harsh environments
- Higher correction = more resilient code, but slightly larger or denser pattern
- SMLLR default is Q — the sweet spot for most print and branding use cases
Which Level Should You Choose?
The right level depends on where and how your QR code will be displayed. For a clean website or email where the code renders pixel-perfect, L gives you the smallest, least dense pattern — easiest to scan at smaller sizes. For a business card or product box, M or Q strikes the right balance. For any code with a logo in the center — or one that will be printed on textured paper, fabric, or outdoor signage — use Q or H. The logo occupies module space; higher correction ensures the remaining modules carry enough data to reconstruct the full payload.
Error Correction and Logo-Embedded QR Codes
When you add a logo to a QR code, you are intentionally obscuring a portion of the data modules. The QR scanner's error correction algorithm fills in the gap. SMLLR's Design Studio defaults to Q (25% recovery) when a logo is present, and recommends H (30%) for logos that exceed 20% of the code area. This is why highly branded QR codes with large central logos continue to scan reliably — the correction layer compensates for the obscured data automatically.
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Frequently Asked Questions
What error correction level does SMLLR use by default?
SMLLR defaults to Level Q (Quartile), which provides approximately 25% data recovery capacity. This is the industry standard for printed marketing materials and provides a good balance between code density and scannability.
Should I use Level H for QR codes with a logo?
Yes, especially if your logo occupies more than 15–20% of the code area. Level H allows up to 30% of the code to be obscured or damaged while remaining scannable. For smaller logos or transparent overlays, Level Q is usually sufficient.
Does a higher error correction level make the QR code harder to scan?
Not harder — but the code becomes slightly denser (more modules). This means it requires slightly more focus from the scanner camera. For most smartphone cameras in 2025, this makes no practical difference. The trade-off is almost always worth it for physical print applications.
Is error correction level selection available on all plans?
Error correction level selection is available on Pro and above plans. Free and Basic users get the default Q level, which is suitable for most use cases. Upgrade to Pro to unlock L, M, Q, and H selection for precise control over your print and digital QR codes.
Does a higher error correction level make the code physically bigger?
It can slightly increase module density at a given data length, though for most short SMLLR redirect URLs the visual size difference between Q and H is minimal.
Can I change the error correction level after a QR code is already printed?
No — error correction level is set at generation time and baked into the code's pixel pattern. If you need a different level, generate a new code with the desired setting before your next print run.
Can I test whether my chosen error correction level actually scans reliably before printing?
Yes. SMLLR's Design Studio provides a live, scannable preview so you can test-scan the exact settings, including error correction level, before exporting for print.
Why does SMLLR default to Q instead of the more common Medium (M) level?
Medium (M) is fine for clean digital use, but Q gives more headroom for the wear, glare, and imperfect printing that real-world physical placements often involve, which is the more common use case on SMLLR.
Does error correction level affect scan speed?
Not meaningfully. Modern smartphone cameras decode any standard error correction level essentially instantly under normal lighting conditions.
Can I set a different default error correction level for my whole team?
Yes, on Enterprise plans you can set an account-wide default so every new code created by any team member starts at your preferred level.
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